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 Li 10 GeP 2 S 12 (LGPS) with high ionic conductivity to enhance the diffusion of Li + and an ultrathin Al 2 O 3 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 Al 2 O 3 , 10 cycles of ultrathin Al 2 O 3 layer achieves the greatest electrochemical performance. The beginning discharge capacity of LLOs@Al 2 O 3 /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@Al 2 O 3 /LGPS) possess the greatest Li + diffusion coefficient (1.58 × 10 −10 cm 2 s −1 ) compared to LLOs (0.85 × 10 −10 cm 2 s −1 ) and LLOs/LGPS (1.10 × 10 −10 cm 2 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.