Yttrium stabilized argyrodite solid electrolyte with enhanced ionic conductivity and interfacial stability for all-solid-state batteries

The inferior electrochemical stability towards Li anode and relatively low ionic conductivity at room temperature of argyrodite Li 6 PS 5 Cl (LPSCl) electrolytes are the intractable challenges for all-solid-state lithium batteries (ASSLBs). Herein, in order to fully address the aforementioned issues, yttrium ion (Y 3+ ) employed as dopant is designed to substitute for P 5+ in LPSCl to boost the Li  +  mobility in electrolyte, as well as to ameliorate the interface stability to Li anode. By introducing appropriate Y 3+ dopant, the optimized LPSCl-0.02Y electrolyte exhibits high ionic conductivity of 3.3 × 10 −3  S cm −1  at 25 °C, which is 2 times higher than that of the pristine LPSCl (1.5 × 10 −3  S cm −1 ). Benefitting from the high ionic conductivity, LPSCl-0.02Y is endowed with superior inhibition ability of Li dendrite nucleation and growth from Li anode, thereby significantly enhancing the (electro)chemical interfacial stability. Impressively, LiNi 0.8 Co 0.1 Mn 0.1 O 2 /Li cell with LPSCl-0.02Y electrolyte delivers high initial discharge capacity (165 mA h g −1  at 0.05C), robust cycling stability (93 mA h g −1 after 100 cycles) and remarkable rate capability (130 mA h g −1  at 0.2C). This rationally designed Y-doped LPSCl electrolyte is highly expected to pave the road for the practical application of ASSLBs, and to deepen the understanding of aliovalent substitution mechanism.