Composite solid electrolytes based on nickel-doped lithium aluminum silicate ceramics enable lithium metal batteries with enhanced interfacial stability and high-rate capability

Abstract

The solid-state electrolyte (SSE) LiAlSiO₄ still does not meet the application requirements for relatively low ionic conductivity. Herein, we developed a series of nickel-doped lithium aluminum silicate ceramics, Li_(1+0.05X)Al_(1−0.05X)N_i0.05XSiO₄ (X = 0–3) (Ni-doped-LASO), with the strategy of aliovalent element doping. A composite solid electrolyte (CSE, thickness = 30 µm), PMPV-LANSO-LiTFSI-552, was fabricated using the obtained Li_1.1Al_0.9Ni_0.1SiO₄ (X = 2, LANSO) ceramics as the SSE, a PMMA (polymethyl methacrylate)/PVDF (polyvinylidene fluoride) (6 : 4, w/w) blend (PMPV) as the polymer matrix, and LiTFSI (lithium bis(trifluoromethanesulfonyl)imide) as the electrolyte salt additive. The electrolyte exhibits an ionic conductivity of 0.84 mS cm⁻¹, a commendable Li⁺ transference number of 0.527 and a uniform Li⁺ ion deposition/exfoliation on the Li metal anode, realizing Li|CSE|Li cells with a stable cycle for 400 hours at 0.5 mA cm⁻² and a constant voltage of 24 mV. The Li‖LiFePO₄ (LFP) full cells with the CSE delivered a discharge capacity of 85.0 mAh g⁻¹ after 400 cycles at a rate of 10C (1700 mAh g⁻¹), with 81.7% capacity retention and more than 99% coulombic efficiency. Meanwhile, the Li‖LiNi_0.8Co_0.1Mn_0.1O₂ (NCM811) cells using the CSEs maintained 80% initial capacity after 180 cycles at 1C (200 mAh g⁻¹), demonstrating compatibility with a high-voltage cathode. This developed Li_1.1Al_0.9Ni_0.1SiO₄ shows application prospects for solid-state lithium metal batteries with high electrochemical performance and low cost.