In the current era of rapid technological development, batteries, as the energy source for numerous electronic devices, play an indispensable role. Polymer batteries, with their unique performance advantages, are gradually becoming the energy cornerstone of modern technology.​
I. Definition and Development History​
Polymer batteries, namely lithium polymer batteries, are closely related to the research of lithium - ion and lithium - metal batteries. Research in the 1980s laid the foundation for their development. In 1991, the first commercial lithium - ion battery came out. Then in 1993, Bellcore in the United States reported the manufacture of polymer ion batteries using the PVDF process, marking the entry of lithium polymer batteries into the public eye. Around the same time, Chinese manufacturers also began to engage in the production of polymer ion batteries.​
II. Structure and Working Principle​
Lithium polymer batteries consist of five thin films, with a total thickness of only 0.1mm. The current collector, positive electrode, negative electrode, solid electrolyte, and insulating layer each perform their functions. A thermal management system is also equipped to ensure battery performance and lifespan. Its working principle is similar to that of lithium - ion batteries. Lithium ions "shuttle" between the positive and negative electrodes to achieve charging and discharging. The charging and discharging reactions are reversible, resulting in good cycle performance.​
III. Charging and Discharging Characteristics​
Under the common constant - current and constant - voltage charging mode, constant - current charging first increases the voltage. When the voltage reaches about 4.2V, it enters the constant - voltage stage, and the current decreases until charging is complete. Polymer lithium - ion batteries have a high capacity density, good adaptability to different temperatures, and excellent cycle life. After 500 1C charge - discharge cycles, the capacity can still remain at 80% or more of the initial capacity.​
IV. Advantages and Disadvantages​
The advantages of polymer batteries are remarkable. They relatively improve the leakage problem, can be made into thin - type and single - high - voltage batteries, have a high theoretical discharge capacity, are lightweight, and have a flexible shape. However, there are also drawbacks. They have potential safety hazards, and the active chemical properties of lithium can easily lead to accidents. Their energy density and cycle times are lower compared to lithium - ion batteries, and the manufacturing cost is relatively high.​
V. Classification and Applications​
According to different electrolytes, they are divided into solid polymer electrolyte lithium - ion batteries, gel polymer electrolyte lithium - ion batteries, and lithium - ion batteries with polymer cathode materials. They are widely used. In the field of portable electronic devices, products like Apple series all use them. In the electric vehicle field, many automakers actively research and apply them. They can also be used in energy storage systems to balance the supply and demand of renewable energy. In the aerospace field, they provide stable power for satellites, drones, and other equipment.​
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