Electrochemical performance of all-solid-state lithium secondary batteries improved by the coating of Li_2O-TiO_2 films on LiCoO_2 electrode

摘要

All-solid-state lithium secondary batteries using LiCOO_2 particles coated with amorphous Li_2O-TiO_2 films as an active material and Li_2S-P_2S_5 glass-ceramics as a solid electrolyte were fabricated; the electrochemical performance of the batteries was investigated. The interfacial resistance between LiCoO_2 and solid electrolyte was decreased by the coating of Li_2O-TiO_2 films on LiCoO_2 particles. The rate capability of the batteries using the LiCoO_2 coated with Li_2Ti_2O_5 (Li_2O 2TiO_2) film was improved because of the decrease of the interfacial resistance of the batteries. The cycle performance of the all-solid-state batteries under a high cutoff voltage of 4.6 V vs. Li was highly improved by using LiCoO_2 coated with Li_2Ti_2O_5 film. The oxide coatings are effective in suppressing the resistance increase between LiCoO_2 and the solid electrolyte during cycling. The battery with the LiC0O_2 coated with Li_2Ti_2O_5 film showed a large initial discharge capacity of 130mAh/g and good capacity retention without resistance increase after 50 cycles at the current density of 0.13 mA/cm~2.