Totally compatible P4S10+n cathodes with self-generated Li+ pathways for sulfide-based all-solid-state batteries

Abstract

All-solid-state lithium sulfur batteries (ASSLSBs) are considered promising candidates for next-generation energy-storage systems due to their enhanced safety and high theoretical energy density. However, usually both solid-state electrolyte (SSE) and conductive carbon need to be incorporated into the cathode composite to provide Li+/electron pathways, leading to the reduced energy density and inevitable SSE decomposition. Moreover, the real electrochemical behavior of S or Li2S cathodes can not be reflected due to the partially overlapped redox reaction of SSE. Herein, a series of unique P4S10+n cathodes for high-performance ASSLSBs that totally do not need any extra SSE additives are reported. Synchrotron-based X-ray absorption near edge structure coupled with other analyses confirmed that ionic conductive Li3PS4 together with Li4P2S6 components can be electrochemically self-generated during lithiation process and partially maintained to provide fast Li+ transport pathways within the cathode layer. This is further evidenced by a 30–43-fold higher reversible capacity for P4S10+n/C cathodes compared to a S/C cathode. Bulk-type ASSLSBs based on the P4S34/C cathode show a highly reversible capacity of 883 ​mAh g−1 and stable cycling performance over 180 cycles with a high active material content of 70 ​wt%. The present study provides a promising approach for generating ionic conductive components from the electrode itself to facilitate Li+ migration within electrodes in ASSLSBs.