Ultrathin interfacial modification of Li-rich layered oxide electrode/sulfide solid electrolyte via atomic layer deposition for high electrochemical performance batteries

Abstract

Herein, Li-rich layered oxides (LLOs) are modified by sulfide solid electrolyte Li₁₀GeP₂S₁₂ (LGPS) with high ionic conductivity to enhance the diffusion of Li⁺ and an ultrathin Al₂O₃ layer is interposed between LLOs and LGPS through the atomic layer deposition (ALD) technique to inhibit the development of the highly resistive space-charge layer, the side reactions and structure transition of the composites, thus excellently promoting the electrochemical properties of the composites in liquid electrolyte. Among the different ALD cycles of Al₂O₃, 10 cycles of ultrathin Al₂O₃ layer achieves the greatest electrochemical performance. The beginning discharge capacity of LLOs@Al₂O₃/LGPS composites comes up to 233.4 mA h g^-1 with a capacity retention of 90.6% and a voltage retention of 97.3% after 100 cycles at 0.2 C. The composites also exhibit the optimal rate capability and a high energy density of 581 Wh kg^-1 at 1 C. The galvanostatic intermittent titration technique test indicates that the composites (LLOs@Al₂O₃/LGPS) possess the greatest Li⁺ diffusion coefficient (1.58 × 10^-10 cm² s^-1) compared to LLOs (0.85 × 10^-10 cm² s^-1) and LLOs/LGPS (1.10 × 10^-10 cm² s^-1). More importantly, charge curves at the beginning of the initial charge and electrochemical impedance spectroscopy curves clearly reveal the inhibition of the development of the highly resistive space-charge layer.