High capacity and rate performance of LiNi0.5Co0.2Mn0.3O2 composite cathode for bulk-type all-solid-state lithium battery

Abstract

A bulk-type compact composite electrode was designed and prepared by standard ball milling and sintering with LiNi_0.5Co_0.2Mn_0.3O₂, 0.44LiBO₂·0.56LiF, and In₂O₅Sn (ITO). The amorphous 0.44 LiBO₂·0.56 LiF solid electrolyte melted during the sintering process and bound the LiNi_0.5Co_0.2Mn_0.3O₂ particles and ITO particles strongly after solidification, yielding a compact structure and an excellent interface between the active material and solid electrolyte. This is the first time the conductive oxide ITO has served as the electronic conductive additive in the composite electrode. The 811 composite electrode delivered a high specific discharge capacity of 140 mA h g⁻¹, and a significantly enhanced surface capacity of 6 mA h cm⁻², which is of critical significance for all-solid-state lithium batteries. For 20 cycles, the composite electrodes exhibited excellent cycling performance and good rate capability. An all-solid-state lithium battery LiNi_0.5Co_0.2Mn_0.3O₂/dry polymer electrolyte/Li was assembled using the composite electrode and cycled at a constant current density of 0.32 mA cm⁻². The surface capacity of the all-solid-state lithium battery was 0.45 mA h cm⁻², comparable with that of reported all-solid-state lithium batteries with commercialized cathode materials, but much lower than that of the composite electrode. Use of the bulk-type compact composite electrode is very promising in the application of all-solid-state lithium batteries with enhanced ionic conductive electrolyte layer and improved interface contact.