1. Positive electrode structure LiFePO4 (lithium iron phosphate) + conductive agent + binder (PVDF) + current collector (aluminum foil) 2. Negative electrode structure Graphite + Conductive Agent + Thickener (CMC) + Binder (SBR) + Current Collector (Copper Foil) 3. Working principle 3.1 Charging process: A power supply charges the battery. At this time, the electron e on the positive electrode runs from the external circuit to the negative pole, and the positive lithium ion Li+ “jumps in†from the positive electrode to “crawl over†the diaphragm. The small hole, "swim" reaches the negative pole and is combined with the electrons that have long since ran. The reaction that occurs on the positive electrode is The reaction occurring on the negative electrode is 3.2 Battery discharge process The discharge has a constant current discharge and a constant resistance discharge. The constant current discharge is actually a variable resistor that can change with the voltage change in the external circuit. The essence of the constant resistance discharge is to add a resistor to the positive and negative electrodes of the battery to allow electrons to pass. From this, it can be seen that the battery does not discharge as long as the electrons on the negative electrode cannot run from the negative electrode to the positive electrode. Both electrons and Li+ act simultaneously, with the same direction but different paths. When discharging, electrons travel from the negative electrode through the electron conductor to the positive electrode, and lithium ion Li+ “jumps†into the electrolyte from the negative electrode, “crawling†over the diaphragm. The small hole, "swim" reaches the positive pole and is combined with the electrons that have long since ran. Second process 1, positive pole piece preparation 1.1 Drying of raw materials (1) Lithium iron phosphate: vacuum baking. (2) Conductive agent: baked at atmospheric pressure. (3) Adhesive: Baking at atmospheric pressure. 1.2 slurry mixing a) Pour NMP into a vacuum mixer, PVDF is added to it; b) The positive dry material is added in four portions on average. c) Stir at high speed under vacuum for 3-5 hours; d) Prepare for coating. 1.3 Coating a) Apply the slurry evenly on the surface of the aluminum foil on a precision coater. The coating thickness can be adjusted according to different requirements. 2, the preparation of the negative pole piece 2.1 Raw materials do not need to be dried. 2.2 Slurry preparation a) Pour pure water into the vacuum mixer. B) Add CMC, stir, completely dissolve; c) Add SBR and deionized water and stir for 60 minutes; d) Add the negative dry material to the mixer in four equal steps. e) High speed vacuum agitation for 3-5 hours; f) Discharge preparation coating 2.3 Coating a) Apply the slurry evenly on the surface of the copper foil on a precision coater. The coating thickness can be adjusted according to different requirements. 3, pole piece rolling The coated pole piece is rolled once on the roll machine to the thickness required by the process. 4, pole piece die cutting The rolled pole piece is cut into the required small pieces on the die cutting machine to prepare the laminated piece. 5, laminated The positive electrode, the negative electrode and the separator are stacked on the automatic laminating machine in a certain order, and the number of layers is in accordance with the process requirements. 6, battery casing welding The positive electrode and the negative electrode are respectively welded on the positive and negative electrodes of the cap, and then placed in an aluminum shell, and the interface between the cap and the aluminum shell is welded by a laser welding machine. 7, battery injection Inject a certain amount of electrolyte. 8, battery formation, volume • high/low temperature fl uids Diaphragm Seal System Dongguan Runfengda F&M Co., Ltd , https://www.rfdphe.com
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Lithium-ion battery principle and compounding process
First, the principle