Tailoring Electrolyte Distributions to Enable High‐performance Li3PS4‐based All‐solid‐state Batteries under Different Operating Temperatures

Abstract

AbstractLi3PS4 shows great potential as solid electrolyte for all‐solid‐state lithium batteries (ASSLBs) due to its high Li‐ion conductivity and excellent mechanical properties. However, its poor interfacial stability with bare high‐nickel active materials in the cathode mixture inhibits the energy density and electrochemical performances of the corresponding LiNi0.6Mn0.2Co0.2O2/Li3PS4/Li−In battery. The Li3InCl6 electrolyte with good electrochemical/chemical stability with bare LiNi0.6Mn0.2Co0.2O2(NCM622), which acts both as a Li‐ion additive in the cathode mixture and as an isolation layer to isolate the direct contact between the sulfide electrolytes and active materials, providing superior solid/solid interface stabilities in the assembled battery. XPS and TEM results confirm that this strategy can mitigate the side reactions between the bare NCM622 and Li3PS4 electrolytes. In‐situ EIS and DRT results prove that this grading utilization of different solid electrolytes can greatly alleviate the poor electrochemical stability between those two materials, yielding smaller interfacial resistances. The corresponding battery delivers high discharge capacities at various C‐rates under different operating temperatures. It delivers a much higher initial discharge capacity of 187.7 mAh g−1 (vs. 92.5 mAh g−1) at 0.1 C with a coulombic efficiency of 87.6% (vs. 71.1%) at room temperature. Moreover, this battery can even show highly reversible capacity with excellent cyclability when the operating temperature lowers to 0 and −20 °C. This work provides a hierarchical utilization strategy to fabricate sulfide electrolytes‐based ASSLBs with high energy density and superior cycling performance combined with highly‐oxidation cathode materials.