Composition Materials Of Lithium-Ion Batteries

A lithium-ion battery consists of the following components: positive electrode, negative electrode, electrolyte, electrolyte salt, adhesive, separator, positive lead, negative lead, center terminal, insulating material, safety valve, positive temperature coefficient terminal (PTC terminal), negative current collector, positive electrode Current collector, conductive agent, battery case.
1. Cathode material
The positive electrode material is lithium-containing transition metal oxide, phosphide such as LiCoO2, LiFePO4, etc., conductive polymers such as polyacetylene, polyphenylene, polypyrrole, polythiophene, active polysulfide compound, etc.; lithium intercalation compound positive electrode material is lithium ion battery important parts of.
The positive electrode material occupies a relatively large proportion in lithium-ion batteries (the mass ratio of positive and negative electrode materials is 3:1 to 4:1), so the performance of the positive electrode material will greatly affect the performance of the battery, and its cost also directly determines the battery life. The cost is high or low.
2. Anode material
Anode materials are carbon materials, nitrides, silicon-based materials, tin-based materials, new alloys, etc. that can store a large amount of lithium; the biggest difference between lithium-ion batteries and secondary lithium batteries is that the former uses lithium intercalation compounds instead of metal lithium as the battery negative electrode Therefore, the research and development of lithium-ion batteries is largely the research and development of negative electrode lithium intercalation compounds.
3. Electrolyte
The electrolyte is an organic solution of lithium salt, a polymer, and an inorganic solid; as an important part of the battery, the electrolyte plays the role of transporting ions and conducting current between the positive and negative electrodes. Choosing the right electrolyte is to obtain high energy density and power density. , long cycle life and the key to lithium-ion batteries with good safety performance.
4. Adhesive
Adhesives are fluorine-containing polymers, ethylene-propylene rubber, carbon-based materials, silica gel-based gels, radioactive cross-linked polymers, etc.; the main function of the adhesive is: to adhere to the active material; to make the active material and the current collector adhere; In the process, the active material is preserved and adhered and the active material and the current collector are adhered; the slurry is formed during the production process to facilitate coating; the volume expansion of the carbon negative electrode when lithium is inserted is alleviated.
5. Diaphragm material
The separator material is porous polyolefin, polyamide non-woven fabric, etc.; the role of the lithium-ion battery separator paper in the lithium-ion battery is to separate the positive and negative materials. The quality of separator paper directly affects the safety performance and capacity of the battery.
6. Positive temperature coefficient terminal
Positive temperature coefficient terminals (PTC terminals) are composite materials of conductive fillers and polymers; positive temperature coefficient terminals prevent excessive battery current. At normal temperature, the resistance of the positive temperature coefficient terminal is very small, but when the temperature reaches about 120°C, the resistance suddenly increases, causing the current to drop rapidly. When the temperature drops, the resistance of the positive temperature coefficient terminal becomes smaller again, and it can be charged and discharged normally.
7. Negative electrode current collector material
The negative current collector material is copper foil, copper mesh, stainless steel mesh, and other metal meshes; the negative current collector material is generally copper foil (10 μm to 20 μm thick). As a non-ferrous metal foil material, copper foil is used for lithium battery negative electrode current collectors. It mainly requires the following three technical indicators: (1) Thickness (8μm～12μm); (2) Tensile strength (>30kg/mm2) ;(3) elongation (>5%)
8. Positive electrode current collector material: the positive electrode current collector material is aluminum foil, etc.; the positive electrode current collector material generally uses aluminum foil (20 μm thick).
9. Conductive agent: Due to the low conductivity of the active material, a conductive agent is generally added to accelerate the transfer of electrons, and it can also effectively increase the migration rate of lithium ions in the electrode material. Commonly used conductive agents are graphite, carbon black, acetylene black, and colloidal carbon.
10. Battery shell: The battery shell is made of steel, aluminum and other materials.