The Study On High-power Characteristic Of 18650S Lithium-ion Battery

Lithium-ion batteries have become the attractive for the application of electric vehicles (EV) and electric tools. The main applications of 18650S lithium-ion battery is the power device to E-book, because of its mature process, according to the command of the marketing, the main work of this paper is aim to the high-power application of the cylinder 18650S, the key point is focusing on the suitable electrolyte system for 18650S high-power batteries, the factors that influence the high capacity rate discharge feature and cycling performance and the issue of the 18650S high-power lithium-ion on safety. Improving the high-power characteristics of batteries by modifying the related system.The Research of electrolyte system is mainly based on several EC and PC solvents to find the influence of different component electrolytes to charge-discharge characteristics , the influence of forming system or different component electrolytes to cycling performance by assembling R2032 coin batteries. In addition, we make characterization to the surface morphology, component attribution and electrochemical feature by SEM, FTIR, CV and EIS. Then comparing the anti-oxidization of different electrolytes by using three electrode to test the electrochemical window, assembling self-made LiMn2O4 half cell to check the special capacity and cycling performance of cathode material in selected electrolyte. In the end we make decision of 1M LiPF6-EC/DMC/EMC as the final electrolyte for 18650S high-power lithium batteries.The improvement of 18650S high-power lithium-ion batteries about high rate discharge and cycling performance is mainly on the design of battery process and electrolyte additives. The design of battery process mainly change the pressing density and multi-leads to increase the high rate discharge and cycling performance, the improvement of electrolyte is adding additives that improve the cycling performance and battery performance at elevated temperature. In addition, we study the film forming feature of additives by SEM, FTIR, CV and EIS.18650S high-power lithium-ion battery on safety mainly focus on the overcharge and thermal stability, it's easy to find the safety dominance of self-made LiMn2O4 as cathode material, comparing to LiCoO2 battery . In addition, we improve the overcharge performance of battery by adding additives.