Constructing Br-Doped Li 10 SnP 2 S 12 -Based All-Solid-State Batteries with Superior Performances

Abstract

Ionic conductivity and electro/chemical compatibility of Li 10 SnP 2 S 12 electrolytes play crucial roles in achieving superior electrochemical performances of the corresponding solid-state batteries. However, the relatively low Li-ion conductivity and poor stability of Li 10 SnP 2 S 12 toward high-voltage layered oxide cathodes limit its applications. Here, a Br-substituted strategy has been applied to promote Li-ion conductivity. The optimal composition of Li 9.9 SnP 2 S 11.9 Br 0.1 delivers high conductivity up to 6.0 mS cm −1 . 7 Li static spin-lattice relaxation ( T 1 ) nuclear magnetic resonance (NMR) and density functional theory simulation are combined to unravel the improvement of Li-ion diffusion mechanism for the modified electrolytes. To mitigate the interfacial stability between the Li 9.9 SnP 2 S 11.9 Br 0.1 electrolyte and the bare LiNi 0.7 Co 0.1 Mn 0.2 O 2 cathode, introducing Li 2 ZrO 3 coating layer and Li 3 InCl 6 isolating layer strategies has been employed to fabricate all-solid-state lithium batteries with excellent electrochemical performances. The Li 3 InCl 6 -LiNi 0.7 Co 0.1 Mn 0.2 O 2 /Li 3 InCl 6 /Li 9.9 SnP 2 S 11.9 Br 0.1 /Li-In battery delivers much higher discharge capacities and fast capacity degradations at different charge/discharge C rates, while the Li 2 ZrO 3 @LiNi 0.7 Co 0.1 Mn 0.2 O 2 /Li 9.9 SnP 2 S 11.9 Br 0.1 /Li-In battery shows slightly lower discharge capacities at the same C rates and superior cycling performances. Multiple characterization methods are conducted to reveal the differences of battery performance. The poor electrochemical performance of the latter battery configuration is associated with the interfacial instability between the Li 3 InCl 6 electrolyte and the Li 9.9 SnP 2 S 11.9 Br 0.1 electrolyte. This work offers an effective strategy to constructing Li 10 SnP 2 S 12 -based all-solid-state lithium batteries with high capacities and superior cyclabilities.