Polymer lithium battery technology -Lithium - Ion Battery Equipment
1 Structural characteristics of lithium-ion batteries
The positive and negative active materials of lithium-ion batteries are all intercalation compounds. During charging, Li+ is extracted from the positive electrode and inserted into the negative electrode through the electrolyte. When discharging, the opposite is true. The charging and discharging process of the battery is actually Li+ intercalation and intercalation back and forth between the two electrodes. The process of coming out, so this kind of battery is also called "Rocking Chair Battery" (RockingChairBatteries, abbreviated as RCB). Its reaction schematic diagram and basic reaction formula are as follows:
2. Polymer lithium-ion battery technology
2.1 Performance characteristics of polymer lithium-ion batteries
The polymer lithium-ion battery refers to a lithium-ion battery whose electrolyte uses a solid polymer electrolyte (SPE). The battery is formed by pressing the positive electrode current collector, the positive electrode film, the polymer electrolyte film, the negative electrode film, and the negative electrode current collector, and the aluminum-plastic composite film is encapsulated outside, and its edges are hot-melted to obtain a polymer lithium ion battery. Since the electrolyte membrane is solid, there is no leakage problem, and the battery design has a greater degree of freedom. It can be connected in series and parallel or a bipolar structure can be used as needed.
The polymer lithium-ion battery has the following characteristics: ①Shaping flexibility; ②Higher mass specific energy (3 times that of MH-Ni battery); ③Wide electrochemical stability window, up to 5V; ④Perfect safety and reliability; ⑤ Longer cycle life and less capacity loss; ⑥ High volume utilization rate; ⑦ Wide range of applications.
Its working performance indicators are as follows: working voltage: 3.8V; specific energy: 130Wh/kg, 246Wh/L; cycle life: >300; self-discharge: <0.1%/month; working temperature: 253-328K; charging speed: 1h to reach 80% capacity; 3h to 100% capacity; environmental factors: non-toxic.
2.2 Positive electrode material
The characteristics and price of a lithium-ion battery are closely related to its positive electrode material. Generally speaking, the positive electrode material should meet: (1) Electrochemical compatibility with the electrolyte solution within the required charge-discharge potential range; (2) mild Electrode process kinetics; (3) highly reversible; (4) good stability in air in the state of full lithium. With the development of lithium-ion batteries, research work on high-performance and low-cost cathode materials is constantly being carried out. At present, research mainly focuses on transition metal oxides of lithium such as lithium cobalt oxide, lithium nickel oxide and lithium manganese oxide.