Interface design for all-solid-state lithium batteries

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Abstract

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^1-4. Here we design a Mg₁₆Bi₈₄ interlayer at the Li/Li₆PS₅Cl interface to suppress the Li dendrite growth, and a F-rich interlayer on LiNi_0.8Mn_0.1Co_0.1O₂ (NMC811) cathodes to reduce the interfacial resistance. During Li plating-stripping cycles, Mg migrates from the Mg₁₆Bi₈₄ interlayer to the Li anode converting Mg₁₆Bi₈₄ into a multifunctional LiMgS_x-Li₃Bi-LiMg structure with the layers functioning as a solid electrolyte interphase, a porous Li₃Bi sublayer and a solid binder (welding porous Li₃Bi onto the Li anode), respectively. The Li₃Bi sublayer with its high ionic/electronic conductivity ratio allows Li to deposit only on the Li anode surface and grow into the porous Li₃Bi 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/Li₆PS₅Cl/Li cell to achieve a capacity of 7.2 mAh cm^-2 at 2.55 mA cm^-2, and the LiNiO₂/Li₆PS₅Cl/Li cell to achieve a capacity of 11.1 mAh cm^-2 with a cell-level energy density of 310 Wh kg^-1 at a low stack pressure of 2.5 MPa. The Mg₁₆Bi₈₄ 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.