High-performance lithium metal batteries based on composite solid-state electrolytes with high ceramic content

The large scale application of solid state lithium metal batteries based on NASICON-type Li 1+x Al x Ti 2-x (PO 4 ) 3 (LATP) electrolyte has been hindered by insufficient ion conductivity and interface instability due to the spontaneous Ti 4+ reduction reaction between Li metal and LATP. To address these issues, Li 1.7 Al 0.3-x Bi x Ti 1.7 (PO 4 ) 3 (0 ≤  x  ≤ 0.03) (LABTP) electrolytes were prepared, and the influence of Bi substitution on the microstructure and conductivity of LATP were investigated. Suitable amount of Bi substitution accelerates densification and improves the ionic conductivity . Furthermore, unlike commonly used polyethylene oxide (PEO) and polyvinylidene difluoride (PVDF), polyvinylbutyral (PVB)-based quasi-solid electrolytes with LABTP is first-time proposed to improve the compatibility and stability of the LATP/Li interface. The synergistic effect of Bi doping and PVB reduces the reduction reaction of Ti 4+ . Small voltage hysteresis is observed in the corresponding Li||Li symmetric cells. The solid-state Li|LABTP@PVB|LiFePO 4 full cell can deliver a high capacity of 146.2 mAh g −1 and a stable cycling performance without reduction after 200 cycles.