Regulating surface base of LiCoO_(2) to inhibit side reactions between LiCoO_(2) and sulfide electrolyte

The interface instability between layered oxide cathode and sulfide electrolyte is a key point affecting the perform ance of sulfide-based all-solid-state lithium batteries.Coating with fast-ionic conductor and constructing core-shell structure can effectively alleviate the interfacial side reactions and improve the interfacial stability between layered oxide and sulfide electrolyte.However,what have been neglected is the surface base(including Li_(2)CO_(3) and LiOH)of layered oxide can also affect the interfacial stability.To clarify this point clearly and improve the interfacial stability,the surface base of LiCoO_(2)(LCO)is regulated and investigated in this work.First,LCO with surface base Li_(2)CO_(3)(LCO@Li_(2)CO_(3))is prepared by the reaction of Co_(3)O_4 and excess Li_(2)CO_(3).Then,the bare LCO is obtained after LCO@Li_(2)CO_(3) is washed with deionized water and calcined again.Besides,LCO with surface base Li_(2)O(LCO@Li_(2)O)is also prepared with the bare LCO and LiOH.As a result,the electrochemical performances of LCO@Li_(2)O are significantly improved and much higher than those of LCO@Li_(2)CO_(3) and the bare LCO electrodes.In particular,LCO@Li_(2)O-2 cathode display the most outstanding electrochemical performances(discharge capacity138.4 mAh·g^(-1)at 0.2C,105 mAh·g^(-1)at 2C and a capacity retention of 95.4%after 150 cycles at 0.5C).The high discharge capacity and excellent cycle stability of LCO@Li_(2)O electrode confirm the effectiveness of regulating the surface base of layered oxide from Li_(2)CO_(3) to Li_(2)O.The surface base regulating is expected to be a simple but effective strategy to construct the stable interface between the cathode and the sulfide electrolyte of the all-solid-state lithium batteries.