NiMH No.7 battery.Lithium-ion battery principle and process flow

　　Lithium-ion battery principle and process flow 1. Principle 1.0 positive electrode structure LiCoO2 (lithium cobalt oxide) + conductive agent (acetylene black) + binder (pVDF) + current collector (aluminum foil) positive electrode 2.0 negative electrode structure graphite + conductive agent (acetylene black) )+Thickener (CMC)+Binder (SBR)+Current collector (copper foil) Negative electrode 3.0 Working principle 3.1 Charging process

　　The power supply charges the battery. At this time, the electrons e on the positive electrode run to the negative electrode through the external circuit. The positive lithium ions Li+ "jump" into the electrolyte from the positive electrode, "crawl" through the winding holes in the diaphragm, and "swim" "It reaches the negative pole and is combined with the electrons that have already run over. The reaction that occurs on the positive electrode is LiCoO2 = charging = Li1-xCoO2 + Xli++Xe (electrons) and the reaction that occurs on the negative electrode is 6C +

　　Discharge includes constant current discharge and constant resistance discharge. Constant current discharge actually involves adding a variable resistor in the external circuit that changes with the voltage. The essence of constant resistance discharge is to add a resistor to the positive and negative terminals of the battery to allow electrons to pass. It can be seen that as long as the electrons on the negative electrode cannot run from the negative electrode to the positive electrode, the battery will not discharge. Both electrons and Li+ move at the same time, in the same direction but in different paths. During discharge, the electrons run from the negative electrode through the electronic conductor to the positive electrode. The lithium ions Li+ "jump" into the electrolyte from the negative electrode and "crawl" across the separator. small hole, "swim" to reach the positive electrode, and combine with the electrons that have run over long ago. 2. Process flow

　　3. Battery defective items and causes: 1. Reasons for low capacity: a. The amount of attached materials is too small; b. The amount of attached materials on both sides of the pole piece is greatly different; c. The pole piece is broken; d. The electrolyte is low; e. Electrolysis The liquid conductivity is low; f. The positive and negative electrodes are not matched properly; g. The porosity of the separator is small; h. The adhesive ages and the attachments fall off; i. The roll core is too thick (not dried or the electrolyte is not penetrated) j. It is not fully charged when dividing the capacity; k. The positive and negative electrode materials have small specific capacities. 2. Reasons for high internal resistance: a. The negative electrode piece and the pole lug are weakly welded; b. The positive electrode piece and the polar lug are weakly welded; c. The positive electrode lug and the cap are weakly welded; d. The negative electrode lug and the shell are weakly welded; e. The rivets and The pressure plate contact internal resistance is large; f. No conductive agent is added to the positive electrode; g. The electrolyte does not contain lithium salt; h. The battery has been short-circuited; i. The porosity of the separator paper is small. 3. Reasons for low voltage: a. Side reaction (decomposition of electrolyte; impurities in the positive electrode; presence of water); b. Failure to form a safe SEI film; c. Leakage of the customer's circuit board (referring to the customer's processing and delivery Returned cells); d. The customer did not spot weld as required (cells processed by the customer); e. Burrs; f. Micro short circuit; g. Dendrites were produced in the negative electrode. 4. The reasons for over-thickness include the following: a. Air leakage in the weld; b. Decomposition of the electrolyte; c. Undried moisture; d. Poor sealing of the cap; e. The shell wall is too thick; f. The shell Too thick; g. The roll core is too thick (too many attachments; the pole piece is not compacted; the diaphragm is too thick). 5. The causes are as follows:

　　a. Not well formed (the SEI film is incomplete and dense); b. The baking temperature is too high → the binder ages → stripped; c. The negative electrode specific capacity is low; d. There are more positive electrode materials and less negative electrode materials; e .The cap leaks and the weld leaks; f. The electrolyte decomposes and the conductivity decreases. 6. Explosion a. The sub-capacity cabinet is faulty (causing overcharging); b. The diaphragm closing effect is poor; c. Internal short circuit 7. Short circuit

　　a. Material dust; b. Broken when loading the shell; c. Scratch (the small diaphragm paper is too small or not padded properly); d. Uneven winding; e. Not wrapped properly; f. There are holes in the diaphragm; g. Burrs

　　8. Open circuit a) The pole lug and the rivet are not welded well, or the effective solder joint area is small; b) The connecting piece is broken (the connecting piece is too short or is welded too far down when spot welding with the pole piece)

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