A polymer lithium battery is a kind of battery that uses polymer as an electrode and electrolyte material. Depending on the material used for the positive and negative electrodes of the battery, there are many different types of polymer batteries. Lithium polymer batteries have higher energy density. And lipo battery can be miniaturized and thinned, lightweight, high safety and low cost. Lithium polymer batteries use polymer materials as the main battery system in at least one or more of their structures.
In terms of shape, lithium polymer batteries have many advantages such as thinning, any area, and any shape. First of all, the negative electrode material carbon, not only has a wide range of sources, but also enables the battery to obtain a high-speed discharge effect. Secondly, because lithium ions are embedded in carbon, it solves the problem that lithium-ion batteries are not safe; third, the overall performance is good and the charging speed is fast.
Lithium polymer batteries use colloidal electrolytes, which have stable discharge characteristics and a higher discharge platform. It also has high-power endurance. Even if it is charged and discharged at high power and used at high frequencies, the charging process can be completed quickly. There is no memory effect at all. The battery’s charge and discharge efficiency is 99.8%. The charge retention ability is strong, and the monthly charge retention rate is greater than 95%.It has excellent internal consistency to ensure the consistency of each “charge and discharge” process and ensure the longest overall battery life.
Lipo batteries are structurally packed in aluminum-plastic flexible packaging. Once a safety hazard occurs, the polymer battery will only bulge. Thus lipo battery is safer than li-ion battery or LiFePO4 Battery.
Lipo Battery Charging Method：
At present, the charging method of polymer lithium batteries generally adopts constant current and constant voltage charging: the battery is first charged with constant current CC. When the battery voltage rises to a certain value (4.2V), the voltage remains unchanged CV, and the current in the circuit drops to very small, and eventually tends to 0.
Electrochemical principle of polymer lithium battery：
Polymer lithium-ion batteries refer to secondary batteries with Li+2 compounds as positive and negative electrodes.The positive electrode adopts the lithium compound LiCoO2, LiNiO2 or LiMn2O4, and the negative electrode adopts the lithium-carbon interlayer compound LixC6. A typical battery system is:
Positive electrode reaction:
negative electrode reaction:
6C+xLi++ xe-=LixC6 Total battery reaction: LiCoO2+6C=Li1-xCoO2+LixC6
Advantages of lithium polymer batteries
- GREAT SAFETY PERFORMANCE: Polymer lithium batteries are structurally packed in aluminum-plastic flexible packaging, which is different from the metal shell of liquid batteries. In the event of safety hazards, lithium-ion batteries will simply explode, while polymer batteries will only bulge, and at most they will be incinerated.
- MORE THICK: The thickness is small and can be made thinner, ultra-thin, the thickness can be less than 1mm, and it can be assembled into a credit card.There is a technical bottleneck in the thickness of ordinary liquid lithium batteries below 3.6mm, while the 18650 battery has a standardized volume. To take a lipo battery with the capacity of 6V 400mAh as an example, its thickness can be as thin as 0.5mm.
- LIGHTER WEIGHT AND LARGER CAPACITY: Batteries with polymer electrolytes do not need a metal shell as a protective outer packaging. Therefore, when the capacity is the same, it is 40% lighter than steel-shell lithium batteries and 20% lighter than aluminum-shell batteries.When the volume is generally large, the capacity of the polymer battery is larger, about 30% higher.
- THE SHAPE CAN BE CUSTOMIZED: The battery can be designed in a variety of shapes. Besides, the lithium polymer battery can be added or reduced according to practical needs. For example, the new notebook of a famous brand uses trapezoidal polymer batteries to make full use of the internal space.
- SMALL INTERNAL RESISTANCE: The internal resistance of polymer batteries is smaller than that of ordinary liquid batteries. At present, the internal resistance of domestic polymer batteries can even be below 35mW, which greatly reduces the self-consumption of the battery and extends the standby time of the mobile phone. It can reach the level of international standards.This kind of polymer lithium battery that supports large discharge currents is an ideal choice for remote control models and has become the most promising alternative to nickel-metal hydride batteries.
- EXCELLENT DISCHARGE CHARACTERISTICS: Polymer batteries use colloidal electrolytes. Compared with liquid electrolytes, colloidal electrolytes have stable discharge characteristics and a higher discharge platform.
- SIMPLE PROTECTION BOARD DESIGN: Due to the use of polymer materials, the battery does not catch fire or explode, and the battery itself has sufficient safety. Therefore, the protection circuit design of the polymer battery can consider omitting PTC and fuse, thereby saving battery costs.
Defects of lithium polymer batteries
(1) EXPENSIVE: The main reason is that the cost is higher, because it can be planned according to customer needs, and the R&D cost in it must be included.Moreover, the shape is changeable and there are many kinds, which leads to the correct and wrong standard parts of various tooling fixtures in the production process, and the capital is added accordingly.
(2) The poor versatility of the polymer battery itself is also caused by sensitive planning. Often, for such a 1mm difference, it is necessary to plan a model for customers from scratch.
(3) As long as it is broken, it will be completely scrapped, and the circuit control needs to be protected. Overcharge or over discharge will cause the reversibility of the chemical substances inside the battery to be damaged, which will seriously affect the life of the battery.
(4) The life span is shorter than that of 18650, because of the use of different materials and materials, some have liquids inside, some are dry or colloidal, and the performance is not as good as that of 18650 cylindrical batteries when discharging at high currents.
Li-ion Battery VS LiPO Battery
- The raw materials are different. The raw materials of lithium-ion batteries are electrolytes (liquid or colloidal); the raw materials of polymer lithium batteries are electrolytes, polymer electrolytes (solid or colloidal) and organic electrolytes.
- Safety is different. Lithium-ion batteries are simply exploded in a high-temperature and high-pressure environment; polymer lithium batteries use aluminum-plastic film as the shell, and when organic electrolytes are used inside, they will not explode even if the liquid is very hot.
- Different shapes, polymer batteries can be thinned, generalized arbitrarily, and shaped arbitrarily. The reason is that their electrolytes can be solid or colloidal rather than liquid. Lithium batteries use electrolytes, which require a sturdy shell as a secondary packaging to contain the electrolyte.
- The battery voltage is different, because polymer batteries use polymer materials, which can be combined into multiple layers in the battery to reach a high voltage, while the nominal capacity of lithium battery cells is 3.6V. In order to reach a high voltage in practical use, multiple batteries need to be connected in series to form a suitable high-voltage operating platform.
- The production process is different. The thinner the polymer battery, the better the production, and the thicker the lithium battery, the better the production. This makes lithium batteries more widely used.
- Capacity, the capacity of polymer batteries has not been usefully improved, and there is still a reduction compared with the standard capacity of lithium batteries.
Lipo Battery Life-Cycle Life
In fact, he life of lithium batteries is related to the number of times the charging cycle is completed, and it is not directly related to the number of charges. Complete charge and discharge cycle determines how long lithium polymer battery last.
To put it simply, for example, a piece of lithium battery only uses half of its power on the first day, and then it is fully charged. If this is still the case the next day, you can charge it in half, and you can charge it twice in total. This can only be counted as one charging cycle, not two.Therefore, it may usually take several recharges to complete a cycle.Every time a charging cycle is completed, the power will be reduced a little.However, the reduction is very small. After a high-quality battery is charged multiple times, it will still retain 80% of the original power. Many lithium-powered products are still used as usual after two or three years. This is the reason.Of course, the life of the lithium battery still needs to be replaced in the end.
The life of lithium batteries is generally 300 to 500 charging cycles.Assuming that the power provided by a complete discharge is Q, if the reduction in power after each charging cycle is not considered, the lithium battery can provide or supplement a total of 300Q-500Q of power during its life.From this we know that if you charge with 1/2 each time, you can charge 600-1000 times; if you charge with 1/3 each time, you can charge 900-1500 times.And so on, if you charge randomly, the number of times is uncertain.In short, no matter how you charge it, the total replenishment of 300Q~500Q of power is constant.Therefore, we can also understand it this way: the life of a lithium battery is related to the total charging power of the battery, and it has nothing to do with the number of charges.The effects of deep discharge and shallow discharge on the life of lithium batteries are not much different.
In fact, shallow discharge and shallow charging are more beneficial for lithium batteries. Only when the power module of the product is calibrated for lithium batteries, there is a need for deep discharge and deep charging.Therefore, products powered by lithium batteries do not have to stick to the process, everything is convenient first, and they can be charged at any time without worrying about affecting their life span.
If lithium batteries are used in an environment higher than the specified operating temperature, that is, above 35°C, the battery’s power will continue to decrease, that is, the battery’s power supply time will not be as long as usual.If you have to charge the device at such a temperature, the damage to the battery will be greater.Even if the battery is stored in a hotter environment, it will inevitably cause corresponding damage to the quality of the battery.Therefore, keeping it at a suitable operating temperature as much as possible is a good way to extend the life of lithium batteries.
If you use lithium batteries in a low-temperature environment, that is, below 4°C, you will also find that the battery life is reduced, and the original lithium batteries of some mobile phones cannot even be charged in a low-temperature environment. But don’t worry too much. This is only a temporary situation. It is different from use in a high temperature environment. Once the temperature rises, the molecules in the battery are heated and immediately return to their previous power. In order to maximize the efficiency of lithium-ion batteries, it is necessary to use it frequently so that the electrons in the lithium battery are always in a flowing state.If you don’t use lithium batteries often, please remember to complete a charging cycle for lithium batteries every month and do a power calibration, that is, a deep discharge and a deep charge.
Main Applications of LiPo Battery
The wide ambient temperature and small size of the lithium-ion battery industry have made lithium-ion batteries widely used in power station energy storage power supply systems, power tools, UPS, communication power supplies, electric vehicles, special aerospace and other fields, and their market demand is extremely considerable.
With the increasing maturity of lithium-ion battery technology in recent years and the pursuit of excellence in aircraft performance by various aircraft manufacturers, lithium-ion battery technology has gradually begun to re-enter commercial operations, and it seems that it has ushered in another spring of development in the special field.High-performance and large-capacity lithium-ion batteries will further meet the electrical energy needs of a new generation of multi-electric civil aircraft, reduce the weight of the aircraft, and promote civil aircraft manufacturers to gradually use them for aircraft emergency lighting, cockpit voice recorder, flight data recorder, recorder independent power supply, backup or emergency power supply, main power supply and auxiliary power unit power supply and other on-board systems.
Lithium-ion batteries are also used a lot in special applications. The current development focus is on special batteries. Although the lead-acid batteries used in modern conventional special applications have the advantages of simple structure, low cost, and good maintenance performance, the performance is not ideal. Countries are actively studying lithium-ion batteries to replace them.
My country’s special research on lithium-ion batteries is not bad. The navy has long adopted lithium-ion-powered lithium-ion battery packs on small underwater submersibles such as miniature underwater vehicles and mine operations, and has achieved success. It has also accumulated a wealth of relevant experience and technology.
The new type of energy storage lithium-ion battery has been used in the field of communications for a long time. In the information age, especially the arrival of the 5G era, communication base stations are particularly important.Lithium-ion batteries are a reliable energy guarantee for communication base stations.In the communications industry, there are the following important applications: outdoor base stations, indoor and rooftop macro base stations with tight space, DC-powered indoor coverage/distributed source stations, central computer rooms and data centers.
Compared with lead-acid batteries, lithium-ion batteries do not contain polluting metals during production and use, and have natural environmental protection advantages.In terms of performance, it is important to have a long life span, and at the same time it has the advantages of high energy density and light weight.With the continuous reduction of the cost of the entire supply chain of lithium-ion batteries, its price advantage has become more prominent. In the field of communications and energy storage, large-scale replacement of lead-acid batteries or mixed use with lead-acid batteries is just around the corner.
4.UPS power supply
With the continuous improvement of lithium-ion battery technology and people’s rejection of pollution caused by lead-acid batteries for EPS emergency power supplies, many customers have also begun to use lithium-ion batteries as batteries for UPS power supplies. UPS power supplies use lithium-ion batteries as energy storage equipment. There are many advantages.
The emergence of lithium-ion batteries as a new energy source is undoubtedly a solution to the problem of natural resources.The battery used in the UPS power supply is a lithium-ion battery. It is important because lithium-ion batteries are excellent in terms of power storage and performance. Therefore, in the UPS power supply, lithium-ion iron phosphate batteries have also become the best choice.