All-Solid-State Lithium Secondary Batteries Using LiMn[sub 2]O[sub 4] Electrode and Li[sub 2]S–P[sub 2]S[sub 5] Solid Electrolyte

Abstract

All-solid-state cells with the (mol %) solid electrolyte were assembled. Cycle and rate performances were evaluated. The cell showed the first discharge capacity of at a current density of and retained the reversible capacity of after 100 cycles. The capacity decreased with increase in the current density, and the overpotential at the beginning of discharge was observed. The discharge capacity was about at a current density of . To identify the cause of the overpotential, impedance measurements were carried out, and resistance components were analyzed by changing the state of charge and by evaluating an all-solid-state symmetric cell. The interfacial resistance between the electrode and the solid electrolyte was identified after the charge process. The transmission electron microscopy observation and energy-dispersive X-ray analysis, showed that Mn slightly diffused from to the solid electrolyte at the interface.