Interface design for all-solid-state lithium batteries.

The operation of high-energy all-solid-state lithium-metal batteries at low stack pressure is challenging owing to the Li dendrite growth at the Li anodes and the high interfacial resistance at the cathodes. Here we design a MgBi interlayer at the Li/LiPSCl interface to suppress the Li dendrite growth, and a F-rich interlayer on LiNiMnCoO (NMC811) cathodes to reduce the interfacial resistance. During Li plating-stripping cycles, Mg migrates from the MgBi interlayer to the Li anode converting MgBi into a multifunctional LiMgS-LiBi-LiMg structure with the layers functioning as a solid electrolyte interphase, a porous LiBi sublayer and a solid binder (welding porous LiBi onto the Li anode), respectively. The LiBi sublayer with its high ionic/electronic conductivity ratio allows Li to deposit only on the Li anode surface and grow into the porous LiBi sublayer, which ameliorates pressure (stress) changes. The NMC811 with the F-rich interlayer converts into F-doped NMC811 cathodes owing to the electrochemical migration of the F anion into the NMC811 at a high potential of 4.3 V stabilizing the cathodes. The anode and cathode interlayer designs enable the NMC811/LiPSCl/Li cell to achieve a capacity of 7.2 mAh cm at 2.55 mA cm, and the LiNiO/LiPSCl/Li cell to achieve a capacity of 11.1 mAh cm with a cell-level energy density of 310 Wh kg at a low stack pressure of 2.5 MPa. The MgBi anode interlayer and F-rich cathode interlayer provide a general solution for all-solid-state lithium-metal batteries to achieve high energy and fast charging capability at low stack pressure.