Study On Improving Performance Of Lithium Ion Battery By Positive Electrode Lithium Salt （Li₆CoO₄ And Li₅FeO₄） For Cathode

Lithium ion battery is one of the most vital energy storage devices in the contemporary world,which is widely used in people’s everyday life.However,when the lithium ion battery experiences first charge and discharge,SEI film is formed on the surface of the anode material,and consumes the lithium source in the active material of the positive electrode.Then huge irreversible capacity loss appears.Aimed at compensating for the irreversible capacity loss in the first lap of the battery,researchers used the method of lithium supplement to replenish battery’s lithium.Cathode lithium supplement has the superioritie of high safety and low cost,and has become the mainstream way of lithium supplement.In this paper,two lithium-rich materials Li₅FeO₄ and Li₆CoO₄ were used for lithium supplement test to improve the discharge capacity and cycle performance of lithium ion battery.Co₃O₄ used as the cobalt source and Li₂O used as lithium source,The preparation of rich lithium material Li₆CoO₄ by the traditional high-temperature solid-state method and the influence of different firing temperatures on the morphology and delithium capacity of Li₆CoO₄ were investigated.This study found that when the firing temperature is 700℃,the delithium capacity is 581.58 m Ah g^-1.Then appropriate amount 8%of Li₆CoO₄ was added to Li CoO₂ and Li FePO₄cathode materials,and the positive electrode and Graphite anode were respectively composed of a full battery.We found that after 50 tests of charge and discharge,this full battery’s discharge specific capacity,this battery’s character,increased by17.79 m Ah g^-1,and another character-the capacity retention rate of the full battery increased by 8.82%.When tests’time was 100,discharge specific capacity of it increased by 17.52m Ah g^-1,and another character-the capacity retention rate of the full battery increased by7.42%at this moment.The preparation of Li₅FeO₄ by instantaneous discharge was investigated.This paper used Fe₂O₃ as the iron source and Li₂O as lithium source.By adding Li₅FeO₄（LFO）to the cathode material,it was indicated that the best addition ratio of LFO was 8%.Though adding Li₅FeO₄to the Li FePO₄/Graphite and Li CoO₂/HC full battery system severally,after charging and discharging 100 cycles,the two full batteries’discharge ability character has been increased respectively by 11.82 and 11.40 m Ah g^-1.The date of capacity retention gets a increased by 6.51%and 13.23%separately.Though adding Li₅FeO₄to the Li CoO₂/Graphite and NCM111/Graphite full battery system severally,after 100 cycles of charge and discharge,the discharge ability character of the two kinds of full battery have been increased respectively by 17.33 and 17 m Ah g^-1.Simultaneously,capacity retention rates of the battery had a certain increase separately by 9.41%and 9.16%.The study content is to replace the iron source with Fe₃O₄ and prepare Li₅FeO₄ by instantaneous discharge method.Though adding 8%Li₅FeO₄to the Li FePO₄/Graphite and Li CoO₂/HC full battery system severally,after charging and discharging 100 cycles,the discharge ability character of the two full batteries has a promotion respectively by 12.12and 13.18 m Ah g^-1.Capacity retention rates increased separately by 6.12%and 13.36%.Though adding Li₅FeO₄to the Li CoO₂/Graphite and NCM111/Graphite full battery system severally,after 100 cycles’charge and discharge,the discharge capacity character of the two full batteries has a promotion respectively by 14.46 and 12.63 m Ah g^-1.Capacity retention rates increased separately by 7.29%and 7.23%.The results indicate that Li₅FeO₄ and Li₆CoO₄ are good materials of anode lithium supplement.