Fabrication of electrode-electrolyte interfaces in all-solid-state rechargeable lithium batteries by using a supercooled liquid state of the glassy electrolytes

摘要

The softening behavior of a 80Li2S·20P2S5 (mol%) glass electrolyte was investigated and a favorable electrode-electrolyte interface was fabricated by sticking the supercooled liquid state of the 80Li2S·20P2S5 electrolyte on active material particles. A dense pellet of the glass electrolyte without an obvious grain boundary or any voids was prepared by softening the 80Li2S·20P2S5 glass by means of a hot press. The electrical conductivity of the pellet was 8.8 x 10~(-4) S cm~(-1) at room temperature. Sticking the solid electrolyte on the Li4Ti5O_(12) active material particles increased the contact area at the electrode-electrolyte interface and the utilization of the active material was increased in the all-solid-state cells. However, LiCoO2 reacted with the solid electrolyte during the hot press and the electrochemical performance of the cells using hot-pressed LiCoO2 with the glass electrolyte degraded. LiNbO3 coating suppressed the reaction of LiCoO2 with the solid electrolyte. The all-solid-state full-cell H4Ti5O_(12)/80Li2S·20P2S5 glass/LiNbO3-coated LiCoO2 prepared by hot press showed a larger reversible capacity of 120 mAh g~(-1) at 0.064 mA cm~(-2) compared with the full-cell prepared by cold press. The softening of the 80Li2S·20P2S5 glass electrolyte is an effective way for increasing the contact area between the active materials and solid electrolyte.