Composition, structure and electrochemical performance of LiSiPSCl electrolyte with Li/Li-In anodes in all-solid-state batteries

Abstract

The lithium silicon phosphor sulfo-chloride (LiSiPSCl) with a Li10GeP2S12-type structure is one of the most promising solid electrolytes (SEs) for all-solid-state lithium-ion batteries (ASSLIBs) due to its currently highest ionic conductivity at RT. In this work, three kinds of LiSiPSCl electrolytes, i.e. Li7.59(10)Si1.95(9)P1.65(7)S11.64(1)Cl0.36(1) (SE-450), Li7.67(12)Si1.90(1)P1.67(1)S11.61(2)Cl0.39(2) (SE-475) and Li7.58(5)Si1.75(4)P1.79(2)S11.54(4)Cl0.46(4) (SE-500), were prepared at 450 / 475 / 500 °C for 8 h through a solid-state method. The assembling of blocking / symmetrical / semi-blocking cells and ASSLIBs, and electrochemical measurements were carried out by coupling the three SEs with two kinds of anodes (Li metal and Li-In alloy) and one cathode of LiNbO3-coated LiNi0.8Co0.1Mn0.1O2 (NCM@LNO). Studies were focused on the relationship among chemical compositions, phase structures and electrochemical properties, as well as the electrolyte/electrode interfacial stability. Results show that LiSiPSCl electrolytes had favorable interfacial stability with Li-In anode and exhibited low polarization voltage (< 20 mV) and decomposition current (< 0.01 mA). The optimized NCM@LNO//SE-475//Li-In of ASSLIBs exhibited a stable long-term cycle performance with a capacity retention of 97.0% (128.4 mAh g−1) after 50 cycles and 81.1% (107.4 mAh g−1) after 100 cycles at 0.1 C. In addition, it exhibited a good rate performance while its capacity retention remained 99.3% (140.6 mAh g−1) after 39 cycles at 0.05 / 0.1 / 0.2 / 0.5 / 0.05 C.