Cost-effective multi-cation doping and lithium concentration optimization in LaCl3-based solid electrolytes for enhanced performance of all-solid-state batteries

Abstract

Multi-cation doping is an effective approach to improve the electrochemical performance of LaCl3-based solid-state electrolytes. Herein, equimolar Ca2+, Zr4+, and Ta5+ are introduced into the LaCl3 lattice with an optimized Li+ concentration to formulate xLiCl-(CaCl2·LaCl3·ZrCl4·TaCl5)0.25 (LCLZT-x). Structural analyses reveal that the optimized LCLZT-0.8 exhibits the characteristics of reduced Li+ hopping distance, local lattice distortion, and cationic disorder, which promotes rapid Li+ transport. LCLZT-0.8 achieves an ionic conductivity of 0.93 mS cm−1 at 25 °C and a low activation energy of 0.330 eV. All-solid-state batteries (ASSBs) utilizing LCLZT-0.8 possess the initial discharge capacities of 136.7 and 164.5 mAh g−1 with LiCoO2 (LCO) and LiNi0.6Co0.2Mn0.2O2 (NCM622) as cathodes, respectively. Additionally, the ASSBs paired with NCM622 deliver enhanced cycling stability within the 3.0–4.2 V (vs Li+/Li) voltage window compared with LCO-based ASSBs. The improved overall electrochemical performance of LaCl3-based electrolytes stems from the collective contribution of multi-cation doping and Li+ concentration optimization.