Tuning a compatible interface with LLZTO integrated on cathode material for improving NCM811/LLZTO solid-state battery

Poor interfacial contact and severe polarization of nickel-rich cathode materials are crucial problems that must be solved in the development of nickel-rich cathode/garnet-type electrolyte solid-state batteries. Herein, a binder-like Li₃PO₄ is introduced via an in-situ calcination process to build a compatible and Li⁺-conductive self-integrated layer of Li_6.4La₃Zr_1.4Ta_0.6O₁₂-Li₃PO₄ on LiNi_0.8Co_0.1Mn_0.1O₂ cathode material, with a newly calculation method for estimating the interface compatibility theoretically. In addition, the routine helps weaken the space charge layer of active material commonly inevitable in the case, as demonstrated by calculation of Density Functional Theory and Atomic force microscopy analysis. With the interface engineering, the in-situ generated Li₃PO₄ tightly fix Li_6.4La₃Zr_1.4Ta_0.6O₁₂ on LiNi_0.8Co_0.1Mn_0.1O₂, improving the compatibility between LiNi_0.8Co_0.1Mn_0.1O₂ cathode material and the solid electrolyte Li_6.4La₃Zr_1.4Ta_0.6O₁₂. As a result, the interface-engineered LiNi_0.8Co_0.1Mn_0.1O₂/Li_6.4La₃Zr_1.4Ta_0.6O₁₂ solid state battery exhibits an initial discharge capacity of 188.8 mAh g⁻¹ at 0.2C (40 mA g⁻¹). Even at 1C, its retention still remained 91.6% (initial value of 130 mAh g⁻¹) after 100 cycles. The SSBs could also work well under high temperature, delivering high initial discharge capacities of 153.4 mAh g⁻¹ (55 °C) and 149.6 mAh g⁻¹ (80 °C) at 1C, respectively. The work provides an effective strategy to improve NCM811-LP-LLZTO SSBs.