The most common types of batteries are lithium polymer and lithium ion. What are their features?

Lithium Polymer Battery Facts

V lithium polymer batteries a solid polymer electrolyte is involved. In the very first examples of batteries of the type in question, created in the 70s, it was present mainly in the dry version. This electrolyte did not actually conduct an electric current, but it could exchange ions formed by lithium compounds. In modern devices - laptops, mobile phones, gadgets - batteries are used, which also contain a certain amount of electrolyte in the form of a gel.

Lithium polymer batteries are capable of delivering high levels of power density based on their size and weight. They are characterized by a rather low self-discharge, do not have the so-called memory effect - when a charged battery, during use, sometimes discharges only to a level that corresponds to the moment the battery is charged (that is, not necessarily to zero), and can also operate over a wide temperature range.

However, lithium polymer batteries are not always safe - especially if they overheat or take too long to charge. Batteries of this type have about 800-900 operating cycles, at which the level of capacity loss does not exceed 20%. The battery loses the same 20% of its performance after 2 years of operation, even if it is not used, but is in storage.

Lithium-polymer batteries are often very small - theoretically, it is possible to produce batteries with a thickness of the order of a millimeter. The use of a metal case in their construction is optional.

Lithium-ion battery facts

Design lithium ion battery consists of electrodes and separators, usually impregnated with liquid electrolyte. The former are represented by aluminum cathodes and copper anodes. The electric charge in batteries of this type is carried by a positively charged lithium ion, which has the ability to be embedded in the crystal lattices of other substances and thus form new compounds. Cathodes in modern lithium-ion batteries are usually represented by lithium compounds with cobalt, nickel, manganese, and iron phosphate.

Batteries of this type are characterized, like lithium-polymer products, by low self-discharge, but slightly exceed them in energy consumption. Lithium-ion batteries do not need to be charged and discharged periodically to maintain functionality.

Outdated models of lithium-ion batteries are considered unsafe to operate, but those that include lithium-iron phosphate cells are found to be reasonably reliable. Like lithium polymer devices, this type of battery will lose capacity over time - even if not used.

Comparison

The main difference between a lithium polymer and a lithium-ion battery lies in the use of a predominantly dry electrolyte in the structure of the former (with a small percentage of gel), while in the latter, as a rule, a liquid electrolyte is used. This predetermines the possibility, first of all, not to use a metal shell in the construction of lithium-polymer batteries and to produce a battery of small size and thickness. In lithium-ion batteries, in turn, it is necessary - otherwise the electrolyte will leak out. The importance of using a metal sheath can make it difficult to reduce the size of battery manufacturers.

Having determined what is the difference between a lithium polymer and a lithium-ion battery, we will reflect the conclusions in a small table.

table

Lithium Polymer Batteries	Lithium-ion batteries
What do they have in common?
They have general principles for the transfer of electric charge - using lithium compounds
Characterized by low self-discharge
No memory effect
There is a common disadvantage in the form of a decrease in capacity over time.
What is the difference between them?
Have in their structure a solid electrolyte (with the addition of gel)	Have a liquid electrolyte in their structure
Does not require a metal sheath and can be small in size	Requires a metal shell, which makes them larger than lithium-polymer batteries
Have a slightly lower energy consumption	Have a slightly higher energy consumption

Portable chargers have become an essential part of modern everyday life. The quality of batteries is the main condition for their performance, efficiency and safety. Charger manufacturers use two types of batteries in the design - lithium-ion and lithium-polymer. For an ordinary consumer, unfamiliar with the features of different types, it often becomes a problem to choose one or another type of battery.

What is the difference between these varieties, which one will be more correct to choose - all these questions require detailed knowledge of each type. In this article, we will reveal the features of lithium-ion and lithium-polymer batteries, introduce them to their technical properties, charging methods, and service life.

Differences between lithium-ion and lithium-polymer batteries

Battery models produced using different technologies perform the same power supply function. The design features of each type affect the reported power, service life, and the degree of explosion protection. It cannot be said unequivocally that a more modern type of battery is better than an outdated one. There are practical advantages and disadvantages to both technologies. Li-pol and Li-ion models have similar operating schemes, but differ in configuration and technical parameters.

To understand which is better - Li-polymer or Li-ion, we will consider in detail each type separately. Comparing the types of batteries and making a choice in the direction of one type or another should be according to the following indicators:

• price;
• weight-to-capacity ratio;
• security;
• intended use in a device for a specific purpose;
• temperature mode of operation.

When choosing one of the two types, consider the scope and financial capabilities.

Lithium-ion batteries: features and characteristics

Initially, lithium-based models were produced using manganese and cobalt as the main element (active electrolyte). Modern lithium-ion batteries have undergone design changes. Their productivity does not depend on the substance used, but on the order in which the elements are placed in the block. The components of a modern Li-Ion battery are electrodes and a separator. Materials - aluminum and copper (copper anodes and aluminum foil as a cathode base).

Special current collector clamps provide the internal connection of the anode and cathode, and the electrolyte impregnation of the separator mass creates a favorable environment for servicing the charge. The positive charges of lithium ions trigger chemical reactions, form bonds, and provide energy output. The principle of operation of the lithium-ion power supply is similar to the operation of a full-size gel battery.

Lithium Polymer Batteries

Since lithium-ion models do not cope with many modern tasks, they gradually began to be replaced by polymer elements. Li-ion batteries were not very safe and were quite expensive. To eliminate these shortcomings and problems of operation, to make the batteries more efficient, the developers decided to change the electrolyte. Instead of impregnating a porous separator, polymer electrolytes were used in the battery design.

The lithium polymer cell has a thickness of 1 mm, which makes the size of the battery compact. Replacing liquid electrolytes with polymer films eliminated the high risk of ignition of the battery and made it safe. The comparison table below will help you to clearly determine how Li-ion differs from Li-Pol.

Specifications	Li-ion	Li-Pol
Energy intensity		low, the number of charge and discharge cycles is less
Standard size	small choice	high selection, independence from the standard cell format
	slightly heavier
		almost twice as high at the same size
Life time	about the same	about the same
Risk of explosion and fire	higher	built-in protection against electrolyte leakage and overcharging
Charging time
	up to 0.1% monthly	less active

The design of polymer-lithium battery devices completely eliminates the presence of an electrolyte in the form of a liquid or gel. You can clearly imagine the difference in technology when considering the principle of operation of modern automotive power supplies. Safety concerns have led to the exclusion of liquid electrolytes from everyday practice. But until recently, impregnated porous structures were used in car batteries.

The introduction of polymer-lithium cells already assumed a solid-state basis. A characteristic difference from lithium-ion batteries is the process of contacting the plate of the active substance with lithium and preventing the formation of dendrites during cycling. It is this feature that protects battery cells from fire or explosion.

Life time

Both lithium-ion and lithium-polymer batteries are subject to intense aging. They provide about nine hundred full charge cycles, after which they become unusable. In this case, it does not matter how active the operation of the device was. If the battery has not been used at all for a long time, the resource will still be reduced.

After a year, the capacities become significantly reduced in resource, and after two or three years, it can be stated that the battery is completely out of order. This is a common disadvantage of lithium batteries, and choosing a more durable model is worth only depending on the manufacturer's reputation and reviews of specific models.

Additional protection

If we consider the question of what is the difference between Li-ion and Li-Pol batteries, you should pay attention to the built-in protective systems. Models operating on a polymer-lithium base require the use of additional internal protection functions. They are characterized by cases of burnout due to overheating of the elements. The internal stress of various work areas leads to such consequences.

In order to protect the device from unauthorized overcharges, from overheating of parts and burnout, a special stabilizing system and a current limiting mechanism are used in the design. This increases the safety of lithium-polymer models, but significantly increases the cost of the battery due to the use of protective elements.

Part of the design involves electrolytic components in the gel formation. Combined batteries are used in many portable appliances. They are extremely sensitive to temperature extremes and require strict adherence to operating rules. The polymer-based battery can be used in devices with heating in the range of 60-100 degrees.

Manufacturers enclose the inner part in a casing with heat-insulating properties - it is convenient to use such batteries in hot climates. In conditions where the temperature regime does not meet the operating requirements, elements with a polymer component are used as backup.

Battery charging features

It takes at least three hours of charging to recharge the Li-Polymer battery. In this case, the unit does not heat up. There are two stages of filling. The first one runs until the peak mode is set, which is maintained until the charge reaches 70%. In normal voltage mode, a residual charge of 30% is accumulated. Recharging must be done on a strict schedule, waiting for full discharge and performing the procedure every 500 hours of using the device. This mode maintains a constant filling volume.

It is only necessary to connect the battery to a stable working power supply, without voltage surges and interference. Use only appropriate chargers that match the characteristics stated in the description. An important point: during the charging process, all connectors must be connected correctly, they must not be allowed to open. Li-Pol cells are extremely sensitive to all kinds of overloads, exceeded current ratings, mechanical shock and hypothermia. The tightness of solid-state elements should be monitored.

Li-ion cells are charged in much the same way as polymer cells, but are more sensitive and less reliable in terms of safety. The charging time for both types is approximately the same, but the polymer element is more "capricious" to the quality of the power supply point.

The Better Li-ion Battery

Lithium-ion batteries are more familiar to the consumer, they have a number of operational advantages:

• the price is lower than the lithium polymer battery;
• standardized sizes allow you not to make mistakes when choosing a model;
• common area of ​​application.

Powerful lithium batteries are effectively used for devices that require high short-term current consumption. The temperature regime, like that of polymer-based devices, is of key importance during operation.

An ordinary user does not feel a tangible difference, but from the point of view of the rationality of the scope of application, this type of battery is convenient in chargers for the following equipment:

• cordless tools (screwdrivers, saws, grinders);
• laptops;
• mobile phones;
• electric vehicles;
• home robots;
• wheelchairs.

Before choosing the optimal type of charging, you need to know exactly for which device it will be used. This is especially important if universal use and maintenance of several portable devices are planned at once.

Lithium polymer batteries can be used efficiently where weight and temperature are important factors. They are "afraid" of frost and are not very convenient for portable tools and gadgets. Therefore, the main area of ​​use is:

• quadcopters;
• airsoft guns;
• toys;
• CCTV Cameras.

When choosing the right type of charger, pay attention to the scope of use, cost and level of safety. Read user reviews about products from different manufacturers and make a choice.

Features of lithium-polymer batteries and rules for their operation

The lithium-polymer battery is a modified version of the lithium-ion battery. The main difference lies in the use of a polymer material that acts as an electrolyte. Conductive inclusions with lithium compounds are added to this polymer. Such batteries have been actively developed in recent years and are used in mobile phones, tablets, laptops, radio-controlled models and other equipment. Despite the fact that lithium batteries are not capable of providing high discharge currents, some special types of polymer batteries can deliver a current that significantly exceeds their capacity. Since lithium polymer batteries are rapidly spreading in the market, you need to have an understanding of their design, rules of operation and safety when handling them. This will be discussed in our today's material.

The advantage of replacing the liquid organic electrolyte with a polymer one is the increased safety of battery operation. This is very important for lithium-type batteries. It was safe commercial use that held back their development from the outset. In addition, the polymer electrolyte gives you much more freedom in choosing the shape of the battery.

The Li-Pol storage battery device is based on the process of transition of a number of polymers into a semiconducting state when electrolyte ions are introduced into them. In this case, the conductivity increases several times. Researchers were mainly engaged in the selection of polymer electrolyte for batteries with metal lithium and Li─Ion models. In theory, an increase in the energy density of batteries with polymer is allowed by several times in comparison with lithium ion batteries. Today, there are several groups of Li-Pol batteries that differ in the composition of the electrolyte:

• With a gel-like homogeneous electrolyte. It is obtained as a result of the introduction of lithium salts into the structure of the polymer;
• With dry polymer electrolyte. This type is made on the basis of polyethylene oxide with various lithium salts;
• Electrolyte in the form of a microporous polymer matrix, in which non-aqueous solutions of lithium salts are sorbed.

If we compare polymer and liquid electrolyte, then it is worth noting the lower ionic conductivity of the former. It decreases significantly at negative temperatures. So, one problem was to find a composition for a high conductivity electrolyte. And the second important task was to expand the operating temperature range of polymer batteries. Models of lithium-polymer batteries used in modern technology are not inferior in their characteristics to Li-Ion.

Since there is no liquid electrolyte in a polymer battery, their operational safety is much higher. In addition, they can be made in almost any shape and configuration.

Containers of some models, in which the can itself is located, are made of metallized polymer. Due to the crystallization of the polymer electrolyte, the parameters of these batteries are significantly reduced at negative temperatures.

There are developments of polymer batteries with a metal anode. Scientists managed to achieve a high current density and a significant expansion of the operating temperature range. These types of rechargeable batteries can also be used in various portable electronics and home appliances. Many leading companies are already engaged in the production of such batteries.

Moreover, different manufacturers may differ in electrode materials, electrolyte composition and assembly technology itself. For this reason, the parameters of these batteries are also very different. However, all manufacturers agree that the stability of Li─Pol is strongly influenced by the homogeneity of the polymer electrolyte. And it depends on the polymerization temperature and the ratio of the components.

Now there are already many experiments that prove a higher level of safety of polymer batteries in comparison with ionic ones. This includes overcharging, overcharging, vibration, shrinking, short circuiting, and piercing of lithium ─ polymer batteries. So, this type of battery has the best development prospects. Below are the results of tests for the safe operation of Li─Pol batteries.

Test type
Test type	Gel polymer electrolyte battery	Liquid electrolyte battery
Needle puncture	There were no changes	Explosion, smoke, electrolyte leakage, temperature rise up to 250 ° С
Heating up to 200 ° С	There were no changes	Explosion, electrolyte leak
Short circuit current	There were no changes	Electrolyte leakage, temperature rise by 100 ° С
Reload (600%)	Bloating	Explosion, electrolyte leakage, temperature rise by 100 ° С

There are examples of lithium-polymer batteries that are 1 millimeter thick. Such models allow mobile designers to create very compact hardware. This opens up new possibilities for reducing the size of electronic devices. To reduce the internal resistance of Li-Pol batteries, a gel electrolyte is added. Batteries used in mobile phones use this type of electrolyte. They combine the features of polymer and ionic batteries.

What is the difference between Li─Ion and Li─Pol rechargeable batteries. They belong to and are close in their electrical characteristics. But polymer models use a solid electrolyte. The gel component is introduced into the electrolyte to reduce the internal resistance of the battery and stimulate ion exchange processes.

In terms of their energy capacity, lithium-polymer storage batteries have a specific energy content 4-5 times higher and 3-4 times higher. Both of these types belong to. Comparison is made with them, since basically lithium batteries have replaced alkaline batteries in mobile electronics.

Li-Pol batteries have a service life of 500-600 charge-discharge cycles (at a discharge current of 2C). According to this indicator, they are inferior to cadmium ones (1 thousand cycles) and approximately correspond to metal hydride ones. The production technology and design are constantly being improved and in the future, perhaps, the characteristics will improve. It is also worth noting that polymer battery loses about 20% of its capacity in 1-2 years. According to this parameter, they correspond to ionic batteries.

It should be noted that there are 2 broad categories among polymer batteries for commercial use. These are regular and fast-discharge ones. The latter are often called Hi discharge. The difference between these groups lies in the maximum permissible discharge current. It can be indicated in absolute value or in multiples of the nominal capacity.

For example, 3C. For conventional storage batteries, the maximum discharge current is no more than 3 - 5C. Fast-discharge models have a maximum discharge current of 8-10C. The weight of the fast-discharge batteries is approximately 20 percent higher than that of standard models. These batteries are labeled with HC or HD.

KKM2500 stands for a regular model with a capacity of 2500 mAh, and the KKM2000HD label stands for a 2000 mAh fast-discharge battery. Fast discharge models are not used in home appliances and consumer electronics. Batteries from cell phones and tablets cannot withstand high discharge currents, and therefore are equipped with protection against such operating modes.

The areas of application of lithium-polymer batteries stem from the tasks that were set during their development. This is an increase in the operating time of the device and a decrease in its weight. Standard Li─Pol models operate in various electronics with low consumption currents. These are laptops, smartphones, e-books, tablets.

Models that provide a fast discharge are also called "power" models. They are used in those devices where high current consumption is required. The most famous field of application for "power" batteries is radio-controlled models. This market is the most attractive for polymer battery manufacturers. In the field of devices with very high discharge currents (up to 50 C), lithium-polymer batteries are inferior to alkaline ones. Perhaps in the future, lithium models will overcome this limitation. In terms of price, they roughly correspond to nickel-metal hydride.

Handling lithium ─ polymer batteries

Security

Lithium-type batteries in general, and polymer in particular, require rather delicate handling during operation. What you need to remember when using Li─Pol batteries:

• Excessive battery charge is harmful (above 4.2 volts per battery cell);
• A short circuit must not be allowed;
• Discharge by currents that lead to heating of the battery over 60 degrees Celsius is inadmissible;
• It is impossible to depressurize the battery;
• Do not discharge the battery below 3 volts;
• Heating above 60 degrees is unacceptable;
• Discharged storage is not allowed.

Failure to follow these rules can lead to a fire at worst, and a significant loss of capacity at best.

In this regard, you can give several recommendations for the safe use of lithium-polymer batteries. First you need to purchase a high-quality charger and set the correct settings on it. In addition, it is recommended to use connectors that do not allow short circuits. Be sure to control the current that is consumed by the device.

It is also worth noting that it is necessary to observe the temperature regime and prevent overheating of the polymer battery. This is the weak point of all lithium-type batteries. If the battery heats up to 70 degrees, then a spontaneous reaction begins in it, which converts energy into heat. The result is ignition and sometimes explosion. If it is possible to control the voltage of the battery, then it should be monitored especially closely at the end of the discharge.

Another reason for the failure of lithium batteries is depressurization. Under no circumstances should air enter the inside of the polymer battery can. The case is initially sealed and should not be subjected to shock or dropped. If you are soldering leads, then this must be done extremely carefully.

Before sending the polymer battery for storage, it is recommended to charge it halfway. Store the battery in a cool place out of direct sunlight. Like all rechargeable batteries, lithium-polymer batteries have a self-discharge rate, but it is less than that of lead or alkaline ones.

Batteries: Li-ion, Li-Pol, Li-ion-pol and the rules for their operation

A bit of history and theory:

The first experiments to create lithium batteries started in 1912 year, but only six decades later, in the early 70s, they first appeared in household devices. Moreover, I emphasize, these were exactly the batteries. Subsequent attempts to develop lithium batteries (rechargeable batteries) have been unsuccessful due to the problems encountered in ensuring their safe operation.

Lithium is the lightest of all metals, has the highest electrochemical potential and provides the highest energy density. Batteries using lithium metal electrodes are capable of providing both high voltage and superior capacity. But as a result of numerous studies in the 80s, it was found that the cyclic operation (charge-discharge) of lithium batteries leads to changes on the lithium electrode, reducing thermal stability and causing the potential for thermal state to go out of control. When this happens, the temperature of the cell quickly approaches the melting point of lithium and a violent reaction occurs with the ignition of the evolved gases. For example, a large number of lithium mobile phone batteries shipped to Japan in 1991 were recalled after several incidents of fire and burns.

Due to the instability inherent in lithium, the researchers turned their gaze towards non-metallic lithium batteries based on lithium ions. Having lost a little at the same time in energy density and taking some precautions during charging and discharging, they got safer so-called Li-ion batteries.

The energy density of Li-ion batteries is usually twice the density of standard NiCd, and in the future, with the use of new active materials, it is expected to increase it and achieve a threefold superiority over NiCd. In addition to the large capacity, Li-ion batteries, when discharged, behave similarly to NiCd (their discharge characteristics are similar in shape, and differ only in voltage).

Today there are many varieties of Li-ion batteries., and you can talk for a long time about the advantages and disadvantages of one type or another, but from the consumer point of view, it is not possible to distinguish them by their appearance. Therefore, we note only those advantages and disadvantages that are inherent in all types and consider the reasons that caused the birth of lithium-polymer batteries.

Main advantages:

• High energy density and, as a result, high capacity with the same dimensions compared to nickel-based batteries.
• Low self-discharge.
• High single cell voltage (3.6 V versus 1.2 V for NiCd and NiMH), which simplifies construction, and often the battery consists of only one cell. Many manufacturers today are guided by the use of such a single cell battery for cell phones (remember Nokia). However, to provide the same power, a higher current must be supplied. And this requires ensuring a low internal resistance of the element.
• Low maintenance (running) cost as there is no memory effect and no periodic discharge cycles are required to restore capacity.

And disadvantages:

• The battery requires a built-in protection circuit (which leads to an additional increase in its cost), which limits the maximum voltage on each battery cell during charging and prevents the cell voltage from dropping too low during discharge. In addition, it limits the maximum charge and discharge currents and controls the cell temperature. As a result, the possibility of metallization of lithium is practically excluded.
• The battery is susceptible to aging, even when not in use and just lying on the shelf. The aging process is common in most Li-ion batteries. For obvious reasons, manufacturers are silent about this problem. A slight decrease in capacity is noticeable after one year, regardless of whether the battery was in use or not. After two or three years, it often becomes unusable. However, batteries of other electrochemical systems also have age-related changes with deterioration of their parameters (this is especially true for NiMH exposed to high ambient temperatures). To reduce the aging process, store the battery, charged to about 40% of the nominal capacity, in a cool place, separate from the phone.
• Higher cost compared to NiCd batteries.

Li-ion battery technology is constantly improving. It is updated approximately every six months and it becomes difficult to assess how well new batteries perform after long-term storage.

In a word, everyone is good Li-ion battery, but there are some safety problems and high cost. Attempts to solve these problems led to the emergence of lithium-polymer (Li-pol or Li-polymer) batteries.

Their main difference from Li-ion lies in the name itself and consists in the type of electrolyte used. A dry solid polymer electrolyte was used, similar to a plastic film and not conducting electric current, but allowing the exchange of ions (electrically charged atoms or groups of atoms). The polymer electrolyte effectively replaces the traditional porous electrolyte-impregnated separator used in lithium-ion batteries.

This design simplifies the manufacturing process, is safer and allows the production of thin, freeform batteries. In addition, there is no danger of ignition as there is no liquid or gel electrolyte. With an element thickness of about one millimeter, equipment developers are free to choose a shape, shape and size, up to the point of introducing it into clothing fragments.

But so far, unfortunately, dry Li-polymer batteries have insufficient electrical conductivity at room temperature. Their internal resistance is too high and cannot provide the amount of current required for modern communication devices and power supply to hard drives of laptop computers. At the same time, when heated to 60 ° C or more, the electrical conductivity increases to an acceptable level, but this is not suitable for mass use.

You may ask how it is, Li-polymer batteries are sold on the market with might and main, manufacturers equip phones and computers with them, and we are saying here that they are not yet ready for commercial use. Everything is very simple. In this case, we are talking about batteries not with a dry solid electrolyte. In order to increase the electrical conductivity of small Li-polymer batteries, some gel electrolyte is added to them. And most of the Li-polymer batteries used for mobile phones today are actually hybrids because they contain a gel-like electrolyte. They are called lithium-ion polymer. But most manufacturers, for promotional and marketing purposes, simply label them as Li-polymer.

First of all, what is the difference between a Li-ion and a Li-polymer battery with the addition of a gel electrolyte? Although the characteristics and efficiency of both systems are very similar, the uniqueness of the Li-ion polymer (you can even call it that) battery is that it still uses a solid electrolyte, which replaces a porous separator. Gel electrolyte is added only to increase ionic conductivity.

All modern phones, smartphones and PDAs are equipped with lithium-based batteries: lithium-ion or lithium-polymer, so in the future we will talk about them. Such batteries have remarkable capacity and service life, but they require very strict adherence to certain operating rules.

These rules can be divided into two groups:

• User independent
• User dependent.

V the first The group includes the fundamental rules for charging and discharging batteries, which are controlled by a device (controller) built into the battery, and also sometimes by an additional controller located in the device itself. These rules are simple:

• The battery must be in a state for its entire life in which its voltage does not exceed 4.2 volts and does not fall below 2.7 volts. These voltages are indications of the maximum (100%) and minimum (0%) charge, respectively. The minimum voltage stated above applies to batteries with coke electrodes, however most modern batteries have graphite electrodes. For them, the minimum voltage is 3 volts.
• The amount of energy given off by the battery when its charge changes from 100% to 0% is its capacity. Some manufacturers limit the maximum voltage to 4.1 volts, while the battery lives longer, but its capacity is reduced by about 10%. Also, sometimes the lower threshold rises to 3.0-3.3 volts, depending on the material of the electrodes, with the same consequences.
• Battery life is greatest at approximately 45 percent charge, and as the charge level increases or decreases, battery life decreases. If the charge is within the limits provided by the battery controller (see above), the change in durability is not significant.
• If, due to circumstances, the voltage on the battery goes beyond the limits indicated above, even for a short time, its lifespan is dramatically reduced. These conditions are called overcharging and overdischarging and are very dangerous for the battery.

Battery controllers designed for different devices, if they (controllers) are made with proper quality, never allow the voltage on the battery during charging to exceed 4.2 volts, but, depending on the purpose of the battery, they can limit the minimum voltage during discharge in different ways. So, in a battery designed for, say, a screwdriver or a motor of a car model, the minimum voltage is likely to be really the minimum acceptable, and for a PDA or smartphone - higher, because the minimum voltage of 2.7-3.0 volts may simply not be enough for the electronics device. Therefore, in complex devices such as telephones, PDAs, etc. the operation of the controller built into the battery itself is complemented by the controller in the device itself.

Let's talk about the process of charging lithium batteries. The charger for any lithium battery is a 5 volt constant voltage source capable of delivering a current equal to approximately 0.5-1.0 battery capacity for charging. So, if the battery capacity is 1000 mA h, the charger must provide a charge current of at least 500 mA, and nominally - 1 ampere.

There are several charging modes for lithium batteries.

Let's start with the standard Sony mode. This mode requires a long charge time, complex controller, but provides the most complete battery charge.

In the first charging stage, lasting approximately 1 hour, the battery is charged with a constant current until the battery voltage reaches 4.2 volts. After that, the second stage begins, which also lasts about an hour, during which the controller, maintaining the voltage on the battery at exactly 4.2 volts, gradually decreases the charging current. When the charging current decreases to a certain value (about 0.2 of the battery capacity), the third stage of charging begins, during which the charging current continues to decrease, and the voltage at the battery terminals remains at the same level - 4.2 volts. The third stage, unlike the first two, has a strictly defined duration determined by the timer built into the controller - 1 hour. After the third stage, the controller completely disconnects the battery from the charger.

The state of charge of the battery at the end of the first stage is 70%, at the end of the second - 90%, and at the end of the third - 100%.

Many companies, seeking to reduce the cost of their devices, use simplified battery charging modes, for example, stopping charging when the voltage on the battery reaches 4.2 volts, that is, using only the first stage of charging. In this case, the battery charges quickly, but, alas, only up to 70% of its real capacity. It is not difficult to determine that your device has just such a simplified controller - it takes about 3 hours to fully charge, no less.

To the second group includes operating rules that we can influence, thereby significantly increasing or decreasing the battery life. These rules are as follows:

• you need to try not to bring the battery to a minimum charge and, moreover, to a state where the machine turns itself off, well, if this happens, then you need to charge the battery as soon as possible.
• there is no need to be afraid of frequent recharges, including partial ones, when the full charge is not reached - this does not harm the battery.

contrary to the opinion of many users, overcharging harms lithium batteries no less, but even more than a deep discharge. The controller, of course, limits the maximum charge level, but there is one subtlety. It is well known that battery capacity is temperature dependent. So, if, for example, we charged the battery at room temperature and received a 100% charge, then when we go out into the cold and the machine cools down, the state of charge of the battery can drop to 80% and below. But the opposite situation may also be. A battery charged at room temperature to 100%, being slightly heated, will become charged, say, up to 105%, and this is very, very unfavorable for it. Such situations occur when using a machine that has been in the cradle for a long time. During operation, the temperature of the device and with it the battery rises, but the charge is already full ...

In this regard, the rule says: if you need to work in the cradle, first disconnect the machine from the charger, work on it, and when it reaches the “combat” temperature regime, connect the charger.

By the way, this rule also applies to owners of laptops and other gadgets.

Ideal conditions for long-term storage of the battery- this is being outside the device with a charge of about 50%. A working battery does not require taking care of itself for months (about six months).

And finally, some more information.

• - Contrary to popular belief, lithium batteries, unlike nickel ones, have almost no “memory effect”, therefore, the so-called “training” of a new lithium battery makes little sense. To calm yourself down, it is enough to fully charge and discharge a new battery once or twice. This is required to calibrate the optional controller.
• - Device owners know that the battery can be charged from both the charger and USB. At the same time, the impossibility of charging from USB is often perplexing. The fact is that according to the “law”, the USB controller must supply the peripheral devices connected to it with a current of about 500 mA. However, there are situations when either the controller itself cannot provide such a current, or the device is connected to a USB controller, on which some peripheral is already hanging that consumes part of the power. So there is not enough current for charging, especially if the battery is too discharged.
• - Lithium batteries DO NOT LIKE FREEZING. Always try to avoid using the clipper in extreme cold - you get carried away and the battery will have to be replaced. Of course, if you took the machine out of the warm inner pocket of your jacket and made a couple of notes or calls, and then put the animal back, there will be no problems.
• - Practice shows that lithium batteries (not only accumulators) decrease their capacity with a decrease in atmospheric pressure (in the highlands, in an airplane). This does not harm the batteries, but you should be aware of this.
• - It happens that after purchasing a battery of increased capacity (say, 2200 mA h instead of the standard 1100 mA h), after a couple of days of using a new battery, the machine starts behaving strangely: it hangs, turns off, the battery seems to be charging, but somehow strange, etc. It is possible that your charger, which successfully works on a “native” battery, is simply not able to provide sufficient charging current for a large-capacity battery. The way out is to purchase a charger with a large current output (say, 2 amperes instead of the previous 1 ampere).

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Lithium polymer batteries represent an improved design of the world renowned lithium-ion batteries. It is planned that these devices will soon completely displace nickel-metal-hydride and nickel-cadmium devices from the market. accumulators... Lithium polymer cells are increasingly being used in a wide variety of electronic devices as a power source. With the same weight in terms of energy capacity, they are several times superior to nickel-metal-hydride and nickel-cadmium designs.

Potentially, lithium-polymer cells will cost less than lithium-ion batteries. However, at the moment they are still quite expensive. At the moment, only a few large firms are engaged in their production. They are similar in design to lithium-ion cells, but they use a helium electrolyte. As a result, they are released by a low discharge current, significant energy density, and a significant number of charge and discharge cycles. Their shape can be very different, and they themselves are distinguished by their light weight and compactness.

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At the moment, lithium-polymer batteries can be of several types, which differ in the structure of the electrolyte:

• Elements having gel-like homogeneous electrolyte , which is created by the introduction into the composition of polymer lithium salts.
• Elements having dry polymer electrolyte ... This type is made on the basis of polyethylene oxide using a variety of lithium salts.
• Having polymer matrix electrolyte having a microporous structure. It contains non-aqueous components of lithium salts.

Due to the fact that a liquid electrolyte is used in a polymer cell, their operational safety is an order of magnitude higher. In addition, they can be manufactured in various shapes and configurations.

Some lithium polymer cells are made of metallic polymer. However, at low temperatures, the parameters of such batteries are significantly reduced due to polymer crystallization.

There are developments in polymer batteries where a metal anode is used. Some companies have managed to obtain a significant expansion of the operating temperature range and current density. These types of batteries can be used in various household appliances and electronics.

At the same time, different manufacturers use different electrode materials, electrolyte structure and assembly technology. As a result, the manufactured batteries can have completely different parameters. But all companies producing such batteries note that the stability of the functioning of lithium-polymer batteries ensures the uniformity of the electrolyte from the polymer. This, in turn, depends on the number of components, as well as the polymerization temperature.

There are already versions of batteries that are only 1 millimeter thick. This allows manufacturers to produce very compact mobile devices.

Also, lithium polymer batteries that are commercially available are divided into:

• Regular.
• Fast-discharge.

Device

Lithium polymer batteries work on the principle of moving a number of polymer elements into semiconducting substances, provided that electrolyte ions are included in them. As a result, there is a significant increase in conductivity. According to the device, these batteries are emitted by an electrolytic composition.

The essence of polymer technology is that the electrolyte is applied to a plastic film. It does not allow electricity to be conducted, but it makes it possible to exchange ions. In other words, the polymer electrolyte replaces the conventional porous separator impregnated with liquid electrolyte. Thanks to the dry polymer structure, it is possible to ensure a minimum cell thickness of about 1 mm, safety of use and ease of production. Thanks to this design, developers have the opportunity to integrate such batteries into shoes, clothing, miniature equipment and other devices.

But a dry polymer battery has disadvantages in the form of a decrease in the conductivity and internal resistance of polymers, which is unacceptable for a number of powerful mobile devices. To make the small polymer battery more advanced, a certain percentage of gel cells are added to the electrolyte. Most of the commercial batteries currently used in cell phones are polymer-gel hybrids. Hybrid batteries are by far the most popular.

Operating principle

Lithium-polymer batteries have a principle of action similar to lithium-ion cells, that is, they operate on the reversibility of a chemical reaction. Here, the anode is a material made of carbon, where lithium ions are embedded. Oxides of vanadium, manganese or cobalt are used in the cathode. The operation of such a battery is based on the ability of polymers to pass into a semiconducting state due to the inclusion of electrolytic ions in them.

Lithium salts are still used here as the chemical base of the electrolyte. However, they are located in a corresponding polymer spacer that is located between the cathode and anode. Thanks to this, lithium polymer batteries can be made in any arbitrary shape. They can be placed in various inaccessible places, which opens up new possibilities for electronics manufacturers.

Application

Lithium polymer batteries are increasingly being used. Such batteries can significantly increase the operating time of the device while reducing the weight of the battery. Thanks to this, it is possible to obtain an energy carrier that will be several times larger in capacity. Even better performance will be achieved with fast discharge batteries. Therefore, such batteries become an excellent option for radio-controlled models of airplanes and helicopters, including other radio-controlled devices.

Application Li-Pol rechargeable batteries makes it possible to reduce the weight of the battery and increase the period of operation of the devices. Lithium polymer batteries have proven their worth in small helicopters such as the Piccolo. Such devices are capable of flying on such batteries for 30 minutes or more. These elements are a good option for small flying structures.

Typical lithium polymer batteries are used as power supplies that are required for electronic devices that draw relatively little current. These can be laptops, smartphones, and so on. Fast-discharge batteries are used in devices where high current consumption is required. Similar batteries are used in modern, portable power tools and radio-controlled devices.

Limitations of use

These batteries will be widely used in the automotive industry in the future. Today they are used to create new technologies and test electric vehicles. However, there are certain limitations that prevent the use of these batteries everywhere.

• Lithium polymer batteries require a special charging mode. In principle, it is not difficult, but the usual cannot be used for this. This is due to the fact that they are distinguished by a fire hazard during the over-discharge period. To combat this phenomenon, all such batteries have an electronic system that prevents over-discharge and overheating.
• If the lithium polymer battery is misused, it may cause a fire.
• A lithium polymer battery should not be used immediately after charging. First, it should be cooled to ambient temperature. Otherwise, the battery may be damaged.
• Inadmissible short circuit.
• Depressurization of the battery is not allowed.
• Battery discharge below 3 volts.
• Do not heat above 60 degrees.
• Batteries should not be exposed to microwaves or pressure. This can lead to the appearance of smoke, fire and more serious consequences.
• It is necessary to protect the battery from damage and shock. Strong mechanical stress can lead to disruption of the internal structure.

However, these disadvantages do not prevent their use in a wide variety of areas. In the future, all these shortcomings will be leveled by the introduction of new technologies and developments.

The advantages of lithium polymer batteries

• Quite high energy density.
• Small self-discharge parameter.
• There is no memory effect.
• Lithium polymer batteries are somewhat superior to lithium counterparts in battery capacity and duration of use.
• Manufacturing batteries with a thickness of only one millimeter.
• Applications in a fairly wide temperature range: from minus 20 to plus 40 degrees Celsius.
• The ability to shape the battery into different shapes.
• Small voltage drop during discharge.