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

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.