All-solid-state lithium secondary batteries using LiCoO2 particles with pulsed laser deposition coatings of Li2S-P2S5 solid electrolytes

Electrode-electrolyte composite materials were prepared by coating a highly conductive Li2S-P2S5 solid electrolyte onto LiCoO2 electrode particles using pulsed laser deposition (PLD). Cross-sections of the composite electrode layers of the all-solid-state cells were observed using a transmission electron microscope to investigate the packing morphology of the LiCoO2 particles and the distribution of solid electrolyte in the composite electrode. All-solid-state cells based on a composite electrode composed entirely of solid-electrolyte-coated LiCoO2 were fabricated, and their performance was investigated. The coating amounts of Li2S-P2S5 solid electrolytes on LiCoO2 particles and the conductivity of the coating material were controlled to increase the capacity of the resulting all-solid-state cells. All-solid-state cells using LiCoO2 with thick solid electrolyte coatings, grown over 120 min, had a capacity of 65 mAh g(-1), without any addition of Li2S-P2S5 solid electrolyte particles to the composite electrode. The capacity of the all-solid-state cell increased further after increasing the conductivity of the Li2S-P2S5 solid electrolyte coating by heat treatment at 200 degrees C. Furthermore, an all-solid-state cell based on a composite electrode using both a solid electrolyte coating and added solid electrolyte particles was fabricated, and the capacity of the resulting all-solid-state cell increased to 95 mAh g(-1). (C) 2010 Elsevier B.V. All rights reserved.