Solid state lithium secondary batteries using an amorphous solid electrolyte in the system (100-x)(0.6Li2S • 0.4SiS2) • xLi4SiO4 obtained by mechanochemical synthesis

Electrochemical cells were constructed using amorphous materials in the system (100 - x)(0.6Li(2)S .0.4SiS(2)). xLi(4)SiO(4), obtained by mechanochemical synthesis, as an electrolyte, LiCoO2 as a positive electrode and indium as a negative electrode. Charge and discharge behaviors of the cells at a constant current were investigated to see the possibility for utilization as secondary batteries. Charge-discharge efficiency at the Ist cycle was more than 75% in the cells using the solid electrolytes synthesized by mechanical milling (MM) for more than 5 h. Charge-discharge curves of the cells using the amorphous materials milled fur more than 10 h, were similar to those of the cells using the corresponding melt-quenched glass samples. The charge-discharge capacity decreased gradually from 90 to 70 mA h/g till about the 10th cycle, and became stable after the 10th cycle. The Coulombic efficiency of the cell showed almost 100%, except for the Ist and 2nd cycles. The amorphous materials synthesized by MM were concluded to work as the electrolyte for solid state lithium secondary batteries, (C) 2001 Elsevier Science B.V. All rights reserved.