Cathode Composite Materials And Their Applications In Lithium-ion Batteries

Nowadays,the most popular cathode materials are layered LiCoO₂?LCO?and Li[NiCoMn]02?NCM?,spinel LiMn204?LMO?,and olivine LiFeP04?LFP?.They all have their own advantages,but there are corresponding shortcomings.LMOcathode materials possess three-dimensional channel for lithium ions,the high voltage platform,rich resource,as well as good safety and is low-cost,and environment friendly,thus,LMO is an ideal candidate for lithium-ion battery cathode materials.However,the eversiblecapacity is as low as 90-120 mAh/gand the capacity fades rapidly in the charge-discharge cycle process.It has been suggested that the capacity fading is due to Jahn-Teller distortion,dissolution of manganese into the electrolyte and decomposition of the electrolyte.In this paper,a new techinique to improve the LMO performance is introduced that the second cathode material of high-capacity,forming a micro-batteries in the positive electrode,reduceLi+ on the surface of the LMOmaterial particle,inhibition Jahn-Teller effect to maintain the integrity of LMO crystal structure,Thereby the obtained lithium ion battery cathode material has a high specific capacity and a long cycle life.The results show that the composite material composed of high potential LMO and low potential LFP,LCO and NCM materials which have higher specific capacity and better cycle life than LMO.When the composite material discharges,Li+ first embeds the high potential LMO,then moves to the low potential material,The enriched Li+ on the surface of LMO material particles doped with low potential material,reduces Li+ on the surface of LMO material particles,stabilizes the structure of the material,inhibits the occurrence of deformity strain.During the charging process,Li+has been removed from the low potential material,the Li+ of the high potential LMO,then migrates to the low potential material to form a "phase de-embedded lithium ion" process to achieve the purpose of charging buffer,thus enhancing the charge and discharge cycle performance of the material.The optimized LMO-NCM composites show excellent performance with high specific capacity,good magnification performance and long cycle life.After the actual production of the battery module,its safety performance and electrochemical performance have reached the national standard.The marketed application shows that the LMO-NCM battery module fully meets the expected performance specifications.