Li3-x Zr x (Ho/Lu)1-x Cl6 Solid Electrolytes Enable Ultrahigh-Loading Solid-State Batteries with a Prelithiated Si Anode

We report two new families of lithium metal chloridesolid electrolytesLi(3-x )Zr( x )(M)(1-x )Cl-6 (0 & LE; x & LE; 0.8; M = Ho or Lu) with ionic conductivitiesof up to 1.8 mS cm(-1) and a low activation energyof 0.34 eV. Structural elucidation via high-resolutionneutron diffraction determines the Li ion distribution in trigonalLi(3)HoCl(6), orthorhombic-I Li3LuCl6, and orthorhombic-II Li2.4Zr0.6(Ho/Lu)(0.4)Cl-6. The last compound exhibits well-connectedLi-ion pathways and abundant Li-ion carriers/vacancies to promotediffusion. All-solid-state batteries with Li2.6Zr0.4(Ho/Lu)(0.6)Cl-6 solid electrolytes and NCM85cathodes exhibit stable cycling up to 4.6 V vs Li+/Li,which is even preserved up to 4.8 V. Stable cathode interphases areformed for both electrolytes upon cycling to 4.3, 4.6, and 4.8 V cutoffpotentials, as identified by a ToF-SIMS analysis. Solid-state cellswith a prelithiated Li0.7Si anode exhibit a significantlyincreased initial coulombic efficiency of 94.5% compared to Si anda high areal capacity of up to 16.3 mAh & BULL;cm(-2).

Automated summary

We report two new families of lithium metal chloride solid electrolytes, Li(3-x)Zr(x)(M)(1-x)Cl-6 (0≤x≤0.8; M = Ho or Lu), with high ionic conductivities of up to 1.8 mS cm(-1) and a low activation energy of 0.34 eV. Structural elucidation reveals the Li ion distribution in three different compounds. All-solid-state batteries with Li2.6Zr0.4(Ho/Lu)0.6Cl-6 solid electrolytes and NCM85 cathodes show stable cycling up to 4.6 V, with stable cathode interphases formed.