Towards high-performance solid-state lithium batteries via antimony doping solid electrolytes

Lithium aluminum titanium phosphate (Li_1.3Al_0.3Ti_1.7(PO₄)₃, denote as LATP) as a highly promising solid electrolyte due to its cost-effectiveness and air stability. However, these issues of low density and high ionic resistance seriously limit its practical applications in solid-state lithium-metal batteries (LMBs). In this work, we use the antimony (Sb⁵⁺) element doping method to synthesis a series of LATP (Li_1.3Al_0.3Ti_1.7Sb_xP_3-xO₁₂, x = 0, 0.02, 0.03, 0.04, 0.05, denote as LATPSx) as solid electrolyte for LMBs. After optimizing, the LATPS0.04 exhibits a higher relative density (98.83 %) and higher ionic conductivity of 6.23 × 10^-4 S·cm^-1 than bare LATP (96.23 % and 1.22 × 10^-4 S·cm^-1). Benefiting from the high density and low ionic resistance, the Li|LATPS0.04|Li cell demonstrates stable cycling for over 1700 h at 0.2 mA·cm^-2. Additionally, the Li|LATPS0.04|LiFePO₄ full cell exhibits an initial discharge specific capacity of 153.78 mAh·g^-1 at 0.1C. Even at 1C, it still shows a reversible specific capacity of 121.84 mAh·g^-1 with a capacity retention rate of 95.50 % after 300 cycles. This work highlighting the significant advantages of Sb⁵⁺ doping LATP solid electrolyte for designing capacity retention and electrochemical stability of LMBs.