TaCl 5 -glassified Ultrafast Lithium Ion-conductive Halide Electrolytes for High-performance All-solid-state Lithium Batteries

For all-solid-state batteries (ASSBs), high ionic conductivity of solid-state electrolyte (SSE) and its good physical contact with the cathode is vital to realize very efficient ion transport inside the cathode layer. In this work, our team introduce a halide glass lithium solid electrolyte LiTaCl6 with ultrahigh ionic conductivity over 10 mS/cm at 25 °C. It is interesting that TaCl5 is able to glassify many simple lithium salts (LiF, LiCl, LiBr, LiI, Li2O, LiOH, Li2O2 and Li2S) and results in a series of glass-phase super lithium-ion conductors \(\text{LiTaCl}_{5}\text{X}_{1/\text{n}}^{\text{n} - }\) (Xn− = F−, Cl−, Br−, I−, O2−, OH−, O2−, S2−) with high room-temperature ionic conductivities ranging from 4.37 to 10.95 mS/cm. Their properties of no grain boundary and fast lithium-ion transport enable ASSBs using a high nickel cathode (LiNi0.91Co0.06Mn0.03O2) with 98.3% capacity retention after long-term 2,000 cycles (4.3 V versus Li+/Li, 1.34 mAh/cm2, 2C rate). Most importantly, \(\text{LiTaCl}_{5}\text{X}_{1/\text{n}}^{\text{n} - }\)-based ASSBs have: 1. excellent electrochemical performance in an ASSB with ultra-high loading over 7 mAh/cm2, 2. ultra-high potential window up to 4.8 V and 92.81% capacity retention after 200 cycles. These results provide new insights in synthesizing halide-based glass SSE and suggest a new approach for realizing ASSB with high voltage and large loading. TaCl5-glassified halide electrolytes has high ionic conductivity over 10 mS/cm at room temperature and high stabiltiy to high nickel cathode, enabling excellent electrochemical performance in an ASSB with untra-high loading over 7 mAh/cm2, ultra-high potential window up to 4.8 V and 92.81% capacity retention after 200 cycles, exhibiting large potential to be used in high performance all-solid-state lithium batteries.