Technological progress is a machine that rolls without stopping! More and more problems of our modern world serve as fuel for this machine. Remember, not so long ago nickel-cadmium (NiCd) batteries were in use, they were replaced by nickel-metal hydride (NiMH). But today the place of lithium-ion (Li-ion) is trying to take the lithium-polymer (Li-pol) batteries. What is the difference between Li-pol and Li-ion? What are the advantages of lithium polymer over lithium-ion batteries? Let's try to figure it out.

When we buy a phone or tablet, few people ask themselves the question - what is the battery inside? Only later, faced with the problem of the rapid discharge of the gadget, we begin to examine in more detail the "internal" of our device.

It became known about lithium batteries in 1912, then the first experiments began, but they did not find wide application. And only in the 70s, after six decades, these charging elements took their place in almost all household devices. Let's emphasize that the conversation is only about batteries, not accumulators.

Lithium is the lightest metal, provides the highest energy density and has significant electrochemical potential. Batteries, which are based on lithium metal electrodes, have a large capacity and high voltage. In the 80s, as a result of numerous studies, it turned out that the cyclic operation of lithium batteries (charge / discharge process) leads to the ignition of the chargers, and after them the gadgets themselves. So, in 1991, several thousand phones were recalled in Japan due to the threat of fire. Because of these dangerous properties of lithium, scientists have turned all their efforts to non-metallic lithium batteries based on lithium ions. And after a while, a safer version of the charger was created, which was named lithium-ion (Li-ion).

Today, a lithium-ion battery is found in almost all mobile devices, it has a large number of varieties, has a lot of positive qualities, but also disadvantages, which we will talk about in more detail.

The advantages of lithium-ion batteries:

High energy density and therefore high capacity

Low self-discharge

Single cell high voltage. This simplifies the design - often the battery consists of only one cell. Many manufacturers today use such a single-cell battery in cell phones (think Nokia)

Low maintenance (operating costs)

No memory effect requiring periodic discharge cycles to restore capacity.

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 protects the cell voltage from being too low during discharge

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 becomes noticeable after a year, regardless of whether the battery was in use or not. After two or three years, it often becomes unusable

Higher cost compared to NiCd batteries.

Lithium Ion Batteries are constantly improving, technology is improving. And everyone would be good with this battery, if not for the safety problems during its use and the high price. All these reasons became the basis for the creation lithium polymer batteries (Li-pol or Li-polymer)... The most obvious and most basic difference between Li-pol and Li-ion Is the type of electrolyte used. The use of a solid polymer electrolyte significantly reduces the cost of the process of creating a battery and makes it safer, and also allows you to create thinner chargers. Why hasn't the lithium polymer battery completely supplanted its predecessor? One of the possible versions, which are expressed by experts - investors who have invested large sums in the development and mass introduction of Li-ion batteries, are trying to return their investments.

Let's summarize. Generally speaking, the lithium polymer battery is a more advanced version of the lithium-ion battery. Judge for yourself:

Advantages of Li-pol and Li-ion batteries

In summary, we can say that, thanks to modern technology, we have two types of reliable external batteries. With the development of mobile technologies, with the advent of smartphones, tablets and many other digital gadgets, with the creation of energy-intensive applications, users are faced with the problem of "dead battery". Of course, both Li-ion and Li-Pol batteries immediately found their way into external chargers.

This is the perfect solution for modern life. The most important thing when choosing a powerbank is not to run into scammers (for more details on how to distinguish a fake from the original, we wrote , but about how to understand the store's website with 100% certainty that they will sell you a fake in it -

27.10.2018

In energy storage production, outdated technologies are rapidly being replaced by new solutions. In the beginning, NiCd batteries were superseded by NiMH cells. Instead, they created more advanced generations of storage batteries - Li-ion, LiFePO4, Li-Pol. In this article, we will consider the differences between Li-ion and lithium-polymer batteries, their advantages and preferences for choice, taking into account the peculiarities of the upcoming use of the battery.

Features of Li-ion technology

Lithium batteries began to be mass-produced in the early 1990s. The functions of the active electrolyte at the initial stage were performed by cobalt and manganese. Now Li-ion storage devices use lithium cobaltate, lithium manganese spinel, lithium ferrophosphate and other compounds as the cathode material. But the key role is played not by the type of substance, but by the peculiarities of its location in the block.

In them, the electrodes (cathode base on aluminum foil and copper anode) are separated by a porous separator, which is impregnated with electrolyte. The cathode and anode in the block are connected by current-collecting terminals. The charge is serviced by positively charged Li ions. They easily pass into the crystal lattices of various substances, create bonds, initiate reactions and cause the release of energy. In principle, Li-ion energy storage devices are similar to full format gel batteries.

The main pros and cons of Li-ion batteries are listed in the table:

Advantages	disadvantages
Small self-discharge - in the 1st month up to 6%, in the following - weaker. The protective circuit consumes about 3% of the accumulated energy per month.	The need to use an integrated protection board. It limits the maximum voltage during charging and does not allow its critical drop during discharge, limits the current limit and controls the temperature.
High energy and discharge current density.	Aging susceptibility even without exploitation.
High cell voltage compared to NiCd and NiMH cells - 3.6 V.	A significant drop in capacity in the cold.
No memory effect and easy maintenance.	Relatively high cost (compared to NiCd batteries).
Long service life.
Small size, light weight.
No maintenance requirements (except for recharging).

The technology for creating Li-ion batteries is improving every year, leading to an increase in the safety of their operation and a decrease in cost.

What is the difference from Li-ion Li-Pol technology?

The improvement of Li-ion batteries was aimed at improving the safety of their use and making the technology cheaper. It was possible to solve this problem by changing the electrolyte - instead of a porous separator with impregnation from an electrolyte, they began to use a polymer electrolyte. Previously, it was used as a plastic film for conducting current. In Li-pol energy storage devices, the element thickness starts from 1 mm, which allows you to get products of all kinds of shapes and sizes.

But the fundamental answer to the question, what is the difference between Li-Pol batteries and Li-ion models, is the non-use of electrolyte in a liquid state and minimizing the risk of ignition. Lithium-polymer batteries contain neither liquid nor gel electrolytes. The active substance is a solid plate and in the area of \u200b\u200bcontact with lithium does not allow the formation of dendrites during cycling. This eliminates the risk of explosions and fires in lithium-polymer batteries.

Initially, Li-Pol current sources had weak conductivity and were not suitable for portable devices. But this drawback was eliminated by using a gel-like electrolyte. Advanced Li-polymer energy storage devices have an electrolyte membrane. For its manufacture, a separator made of propylene or porous polyethylene, which contains a polymer, is used. Interacting with the electrolyte liquid, it becomes gelatinous.

Advantages and disadvantages of Li-Pol current sources

An important advantage of lithium polymer batteries is their excellent capacity to weight ratio. Due to this quality, Li-Pol current sources are widely used in equipping quadrocopters and other radio-controlled models, in mobile phones and digital technology. The key pros and cons of Li-polymer batteries are shown in the table:

Advantages	disadvantages
Light weight combined with high capacity.	Relatively high cost.
The ability to create a battery of arbitrary dimensions and shapes, including very thin ones.	The need for a special recharging mode.
Fast charging.	The need to balance the cells.
Lack of memory effect.	Sensitive to deep discharge, overcharge, low temperatures.
Low wear.
High degree of reliability and safe operation.
Small self-discharge - up to 5% per month.
Unpretentious maintenance.
Less wear and tear and self-discharge.

Which is better, Li-polymer or lithium-ion battery?

The answer to this question depends on where and under what conditions the selected current source will be used. The main characteristics of Li-ion and Li-Pol batteries are similar. Various geometric parameters and technical characteristics are collected from Li-ion cells. It is permissible to use them in the range from -20 to +60 ° C, but at borderline temperatures, faster aging occurs.

Li-Pol batteries are produced in all possible geometries, are characterized by significant energy density and are extremely safe. They are most in demand when a compact and reliable power source is required. The operating temperature range of currently produced Li-Pol batteries is identical to the temperature range of Li-ion.

Comparison table of Li-ion and Li-Pol batteries

To find out, taking into account individual priorities, which is better, a Li-polymer or a lithium-ion battery, you need to compare their characteristics. It's easy to do with a comparison table:

Characteristic	Li-ion batteries	Li-Pol batteries
The number of cycles
Selection of standard sizes	Narrow, there are models in the form of a cylinder and a prism, the most popular cylindrical size is 18650.	Wide, without standard battery format frames, it is possible to create cells with a thickness of 1 mm.
	A bit more	Lightweight - through the use of a gelled electrolyte and the reduction of metal elements.
Capacity with identical dimensions		Higher, almost doubled.
Energy density per unit mass	From 100 to 190 Wh / kg, depending on the cathode material.	130 to 200 Wh / kg.
Service life	Approximately the same: for lithium-ion - from 500 to 2000 charge-discharge cycles, depending on the cathode material, for lithium-polymer - 800 - 1000 cycles.
Risk of explosion or fire	Present, but the use of the protection board eliminates this risk.	Minimized - due to the absence of electrolyte leakage and the use of integrated overcharge protection.
Permissible temperatures	From -20 to +60 ° С, optimally - from 0 to +30 ° С.
Duration of charging
Voltage (nominal)
Discharge limit voltage
Optimal and peak load current	<1С и ˃2С, где С – значение емкости.
Charge Features	With a current of 0.1 ... 1C until reaching 4.1 ... 4.2 V, and then at a constant voltage.
Wear rate (natural aging)	About 0.1% per month.	Below, 20% in 2 years.
Voltage surges during discharge

According to this table, it is easy to compare the better, and in what parameters they are inferior to lithium-polymer analogs.

Summing up

Lithium-ion power supplies are widely used in various fields. They are used to equip digital electronics, personal electric vehicles, robots, cordless tools, wheelchairs, and a host of other devices. They have standardized sizes, are easily matched to the required parameters and are well known to consumers. Powerful batteries are successfully used for devices requiring high short-term current consumption.

Lithium-polymer energy storage devices allow you to obtain the required capacity with a smaller size and mass of the power source, therefore, they are in demand in portable devices, quadcopters, toys, and airsoft guns. The main differences between Li-polymer batteries are their higher price, greater variability of shapes and fewer internal loads.

In practice, both types of batteries have similar characteristics, so the selection preferences depend mainly on the area of \u200b\u200buse. In addition to the type of battery and the cathode substance, the quality of the raw materials used and the production technology affect the characteristics of the current source.

We bring to your attention informative material about.

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 unable to provide 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 be familiar with their design, rules of use 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 them back from the start. 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 their electrolyte composition:

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 the electrolyte with high conductivity. 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 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 uniformity 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, that 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	Battery with liquid electrolyte
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 capacity of 4-5 times more and 3-4 times higher. Both of these types belong to. Comparison is made with them, since mainly lithium batteries have replaced alkaline 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 lose to cadmium (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 in 1-2 years a polymer battery loses about 20% of its capacity. According to this parameter, they correspond to ionic batteries.

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

For example, 3C. For conventional storage batteries, the maximum discharge current is not more than 3 - 5C. Fast-discharge models have a maximum discharge current of 8-10C. Fast-discharge batteries are approximately 20 percent heavier than 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 applications 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

Safety

Lithium-type batteries in general, and polymer batteries 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 should also be noted that the temperature regime must be observed and the polymer battery must not overheat. 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 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 are self-discharge, but less than lead or alkaline.

The constant advancement of technology is beneficial to many aspects of human life. The need for high-performance power supplies with a good balance of safety, cost and performance has led to the development of lithium polymer cells.

Curbing

What is lithium polymer battery

Li polymer batteries are galvanic power supplies in which polymer materials saturated with lithium are used as the electrolyte.

Lithium polymer technology has become a new stage in the development of lithium-ion power supplies, which has reduced the cost of their production and allowed the creation of miniature and flexible batteries.

When buying and using such batteries, you must understand the markings on them, which have the following features:

battery capacity is indicated in mAh;
the number next to the English letter S in the marking indicates the number of individual cells (cans) in the battery, each of which has a nominal voltage of 3.7 volts and a maximum of 4.2 volts;
the number next to the letter C indicates the maximum current output in C. The maximum discharge current in milliamperes per hour is equal to the battery capacity multiplied by this value;
the number next to the letter P indicates the number of cans connected in parallel. When using one can, this value is usually not indicated.

Thus, the designation 2600 mAh 3S 20C denotes a Li-polymer battery with a capacity of 2600 mAh with a nominal voltage of 11.1 volts (maximum 12.6 volts), with three banks connected in series and an allowable discharge current of 52 amperes (2600x20 \u003d 52000 mA).

How lithium polymer batteries are manufactured

The following technology is used in the production of Li-polymer power supplies:

A controlled application of a suspension with active materials of the cathode and anode (two different processes) is carried out on the surface of an aluminum or copper foil, which acts as a current collector.
The foil with the applied material is dried, cut into elements of the required size and shape.
A polymer electrolyte separator is being prepared, which is then placed between foil layers with active materials of the cathode and anode.
The multi-layer battery is assembled, sealed and dried.
When using a polymer separator, which requires inclusions of gel electrolyte, it is filled with the required amount of electrolyte liquid.
Installation of contact pads, packing in a protective shell and trimming of its protruding parts are performed.
External battery terminals are installed.
A charge / discharge control cycle and testing are performed.
Rejection, sorting by capacity and application of appropriate designations is carried out.
If necessary, wires are soldered to the battery terminals.
Quality control is carried out, the battery cells are packed into a case, on which the necessary marking and packaging is applied.

The principle of operation and device of a lithium polymer battery

The principle of operation of Li pol batteries is based on the use of the semiconductor effect in polymer substances with inclusions of electrolyte ions. The addition of an electrolyte to polymers causes an increase in their ionic conductivity while maintaining the insulating properties of the plastic with respect to electrons.

The electromotive force against lithium ions arises as a result of a reversible chemical reaction between an anode (plus) made of carbon (usually graphite) and a cathode (minus) made of cobalt, vanadium oxide or manganese, placed in a polymer electrolyte with lithium salts.

There are three types of polymer electrolytes:

Completely dry polymer electrolytes, which are plastic with the addition of lithium salts, give a low current at room temperature, insufficient for most modern devices and are more expensive than conventional lithium-ion batteries.
Gel polymer electrolytes, which are dry polymer electrolytes interspersed with plasticizers-solvents, have acceptable capacitance, amperage and cost values \u200b\u200band are most often used in practice.
Non-aqueous solutions of lithium salts distributed in a microporous polymer matrix by absorption.

Massively sold Li Po batteries are actually hybrids that combine not only a pure dry polymer electrolyte, but also a small amount of gel electrolyte, which is also contained in lithium-ion sources.

The addition of inclusions of gel electrolyte to a solid polymer electrolyte increases its ionic conductivity and electrical characteristics, in particular, the operating current increases to the value required for most modern small-sized devices.

Lithium polymer battery: pros and cons

Li-polymer power supplies have the following advantages:

high energy density in relation to their mass, 4-5 times higher than that of nickel-cadmium batteries, and 3-4 times higher than that of nickel-metal hydride power supplies;
low self-discharge current and high current efficiency;
the ability to create flexible and very thin products;
lack of memory effect;
maintaining voltage within acceptable limits during a working discharge;
a large range of permissible temperatures during operation (from -20 to +40 degrees).

Lithium polymer batteries have some disadvantages:

fire hazard in case of overcharge / overheating. These batteries require the use of protective electronics that monitor the charging current and temperature, and a special charging algorithm;
the effect of aging, leading to a decrease in capacity during long-term storage and operation (it is believed that the battery loses up to 20% of its capacity for each year);
failure with deep discharge (below 3 volts);
fear of overheating above 60 degrees and overcharging above 4.2 volts (an explosion is possible at a voltage above 4.5 volts);
the use of a thin shell (usually in the form of foil) in some of these batteries reduces the cost of Li Pol cells, but at the same time reduces their strength.

Where are Li Pol batteries used

Due to its low weight and high power, this type of power supply is widely used to supply power to small and large devices, including:

mobile phones and smartphones;
radio-controlled models, quadcopters, microplanes;
power tool;
digital technology, ultrabooks;
electric vehicles.

Rules for the operation of Li Pol batteries

To ensure the required level of safety and prolong the life of serviceable batteries, you must adhere to the following rules:

in the presence of damage, swelling of the batteries, they cannot be used, but must be disposed of;
the batteries must be charged with a quality charger under supervision, not allowing the battery to overheat. If during charging there is a smell of burning, swelling, inflammation, you must immediately stop it and disconnect the battery from the charger;
it is better to charge on a non-combustible surface, for example, on a ceramic tile or porcelain plate; after fully charging the power source, it is better to let it cool down and only then start using it;
discharge below 3 volts, overheating or hypothermia, which reduce the capacity and the total number of charge-discharge cycles, must not be allowed;
the longest service life of LiPo cells is achieved while maintaining their charge level at 45%;
the best charging mode for LiPo batteries is provided by Sony chargers for about three hours. It takes place in three stages:
- First, for about one hour, it is charged up to 70% with a constant current of 0.5-1 from the current output of the battery to a voltage of 4.2 volts;
- Recharging for 1 hour to 90% with a voltage of no more than 4.2 volts with a gradually decreasing current (up to about 0.2 from the current output);
- At the third stage, it is recharged for an hour up to 100% with a small constantly decreasing current.

Cheap chargers run out of charge at the first stage, when the voltage reaches 4.2 v, so the battery does not reach its full capacity.

avoid shocks to the battery, short circuits or discharge with very high currents, overcharging above 4.2 volts per element of the composite battery - all these reasons can cause a fire;
if composite batteries of several Li Pol cells are used, then it is better to charge them separately, or use a special equalizing charge with balancing for each cell. The principle of operation of such a device is to stop the charge of individual elements when they reach a voltage of about 4.17 volts;
before commissioning new batteries, it is best to calibrate them by fully charging and discharging them twice.

In some Li Pol batteries, at a discharge below 2.5 volts, lithium metallization is possible, which leads to the creation of conductive bridges inside the battery and a short circuit. When charging such a battery, uncontrolled heating occurs, which can lead to an explosion of such a power source. Therefore, it is better not to use batteries in which the voltage has dropped below the critical level of 3 volts, and when the voltage drops to 2.5 volts and below, they must be disposed of.

How to store lithium polymer batteries

It is advisable to store charged LiPo batteries in protective cases at room temperature when charging at 3.6-3.8 volts.

Before storing LiPo cells, it is recommended to charge them up to 40-50%, disconnect them from the devices that they power and periodically, at least once every six months, check the charge level.

Disposal of lithium polymer batteries

Disposal of LiPo power supplies is of particular relevance due to their high fire hazard. They are less toxic than nickel-cadmium batteries, but still contain environmentally harmful substances.

To completely and safely dispose of Li-polymer batteries, the following requirements must be observed:

the disposal of discharged batteries is carried out in plastic containers with a water-salt solution (about half a glass of salt per 1 liter of water) for about 2 weeks (until gas formation stops) in a non-residential area. Then they can be thrown away with your regular waste;
before disposal, the batteries must be discharged to at least one volt (this can be done with a light bulb as a load);
if the battery case is damaged, then it does not need to be discharged, but it is necessary to dispose of it in a water-salt solution;
if the discharge is carried out with a current that is more than the permissible one, associated with the value of the maximum current output C, then the battery should be in a bucket of sand or in another place protected from fire;
mechanical destruction of batteries untreated in saline solution is not allowed, due to which a fire may occur. Cells with a cobalt cathode are especially dangerous in this respect.

The growing consumer interest in mobile gadgets and high-tech portable technology in general forces manufacturers to improve their products in a variety of ways. At the same time, there are a number of common parameters, the work on which is carried out in the same direction. These include the method of energy supply. Just a few years ago, active market participants could observe the process of displacement of NiMH by more advanced elements of nickel-metal hydride origin. Today, new generations of batteries are competing with each other. The widespread lithium-ion technology is successfully replacing the lithium-polymer battery in some segments. The difference from the ionic in the new unit is not so noticeable for an ordinary user, but in some aspects it is significant. At the same time, as in the case of competition between NiCd and NiMH elements, the replacement technology is far from flawless and in some respects is inferior to its analogue.

Li-ion battery device

The first models of serial lithium batteries began to appear in the early 1990s. However, cobalt and manganese were then used as the active electrolyte. In modern ones, it is not so much the substance that is important as the configuration of its placement in the block. Such batteries consist of electrodes which are separated by a pore separator. The mass of the separator, in turn, is impregnated with the electrolyte. As for the electrodes, they are represented by a cathode base on an aluminum foil and a copper anode. Inside the block, they are interconnected by current collector terminals. Servicing charge performs a positive charge on the lithium ion. This material is advantageous in that it has the ability to easily penetrate into the crystal lattices of other substances, forming chemical bonds. However, the positive qualities of such batteries are increasingly not enough for modern tasks, which led to the appearance of Li-pol cells, which have many features. In general, it is worth noting the similarity of lithium-ion power supplies with full-size helium batteries for cars. In both cases, the batteries are designed with physical usability in mind. In part, this direction of development was continued by polymer elements.

Lithium polymer battery device

The impetus for improving lithium batteries was the need to combat two shortcomings of existing Li-ion batteries. Firstly, they are unsafe to operate, and secondly, they are quite expensive in terms of price. The technologists decided to get rid of these disadvantages by changing the electrolyte. As a result, the impregnated porous separator was replaced by a polymer electrolyte. It should be noted that the polymer has previously been used for electrical purposes as a plastic film that conducts current. In a modern battery, the thickness of the Li-pol cell reaches 1 mm, which also removes restrictions on the use of various shapes and sizes from developers. But the main thing is that there is no liquid electrolyte, which eliminates the risk of ignition. Now it's worth taking a closer look at the differences from lithium-ion cells.

What is the main difference from an ionic battery?

The fundamental difference lies in the rejection of helium and liquid electrolytes. For a more complete understanding of this difference, it is worth referring to modern car battery models. The need to replace the liquid electrolyte was driven, again, by safety concerns. But if, in the case of automobile batteries, progress stopped at the same porous electrolytes with impregnation, then lithium models received a full-fledged solid base. What is so good about a solid-state lithium polymer battery? The difference from the ionic one is that the active substance in the form of a plate in the contact zone with lithium prevents the formation of dendrites during cycling. This factor excludes the possibility of explosions and fires of such batteries. This is only about the merits, but there are also weaknesses in the new batteries.

Lithium polymer battery life

On average, such batteries can withstand about 800-900 charge cycles. This indicator is modest against the background of modern analogues, but even this factor cannot be considered as a determining element resource. The fact is that such batteries are subject to intense aging, regardless of the nature of their operation. That is, even if the battery is not used at all, its resource will be reduced. It doesn't matter if it's a lithium-ion battery or a lithium-polymer cell. All lithium-based power supplies are characterized by this process. A significant loss in volume can be noticed within a year after the acquisition. After 2-3 years, some batteries fail altogether. But a lot depends on the manufacturer, since within the segment there are also differences in the quality of the battery. Similar problems are inherent in NiMH cells, which age when exposed to sharp temperature fluctuations.

disadvantages

In addition to problems with rapid aging, such batteries need additional protection system. This is due to the fact that internal stress in different areas can lead to burnout. Therefore, a special stabilization circuit is used to prevent overheating and overcharging. This system also has other disadvantages. The main one is the current limitation. But on the other hand, additional protective circuits make the lithium polymer battery safer. The difference from the ionic in terms of cost also takes place. Polymer batteries are cheaper, but not much. Their price tag is also increasing due to the introduction of electronic protective circuits.

Operational Features of Gel Modifications

In order to increase the electrical conductivity, the technologist still adds a gel-like electrolyte to the polymer elements. There is no talk of a complete transition to such substances, since this contradicts the concept of this technology. But in portable technology, it is often hybrid batteries that are used. Their peculiarity lies in their sensitivity to temperature. Manufacturers recommend using these battery models in an environment between 60 ° C and 100 ° C. This requirement also defined a special niche for application. Gel models can only be used in hot climates, not to mention the need to immerse themselves in a thermally insulated case. Nevertheless, the question of which battery to choose - Li-pol or Li-ion - is not so acute in enterprises. Where temperature is particularly important, combined solutions are often used. In such cases, polymer elements are usually used as backup.

Optimal charging method

Typical replenishment time for lithium batteries is on average 3 hours. Moreover, the unit remains cold during charging. The filling takes place in two stages. At the first, the voltage reaches its peak values, and this mode is maintained up to 70%. The remaining 30% are recruited already under normal stress conditions. Another question is also interesting - how to charge a lithium-polymer battery if it is necessary to maintain its full volume in a constant mode? In this case, the charging schedule should be followed. It is recommended to perform this procedure approximately every 500 hours of operation with a complete discharge.

Precautionary measures

During operation, you should use only a charger of the appropriate characteristics, connecting it to a network with a stable voltage. It is also necessary to check the condition of the connectors so that the battery does not open. It is important to consider that, despite the high degree of safety, it is still a type of battery sensitive to overloads. The lithium polymer cell does not tolerate overcurrents, excessive cooling of the external environment and mechanical shock. However, according to all these indicators, polymer blocks are still more reliable than lithium-ion ones. Still, the main aspect of safety is the harmlessness of solid-state power supplies - provided, of course, that they are kept sealed.

Which battery is better - Li-pol or Li-ion?

This issue is largely determined by the operating conditions and the target of the energy supply. The main advantages of polymer devices are rather tangible for the manufacturers themselves, who can more freely use new technologies. The difference will be subtle to the user. For example, in the question of how to charge a lithium polymer battery, the owner will have to pay more attention to the quality of the power supply. In terms of charge time, these are identical elements. As for durability, the situation in this parameter is also ambiguous. The aging effect is more characteristic of polymer elements, but practice shows different examples. For example, there are reviews of lithium-ion cells that become unusable after a year of use. And polymer in some devices are operated for 6-7 years.

Conclusion

Around the batteries, there are still many myths and false judgments that relate to various nuances of operation. Conversely, some of the features of batteries are hushed up by manufacturers. As for the myths, one of them refutes the lithium polymer battery. The difference from the ionic analogue is that polymer models experience less internal stress. For this reason, charging sessions that have not yet run down batteries do not adversely affect the performance of the electrodes. If we talk about the facts hidden by manufacturers, then one of them concerns durability. As already mentioned, the battery life is characterized not only by a modest indicator of charging cycles, but also by the inevitable loss of the useful volume of the battery.