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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.

Oxygen evolution reaction (OER) is a necessary procedure in various devices including water splitting and rechargeable metal-air batteries but required a higher potential to improve oxygen evolution efficiency due to its slow reaction kinetics. In order to solve this problem, a heterostructured electrocatalyst (Co3O4@FeOx/CC) is synthesized by deposition of iron oxides (FeOx) on carbon cloth (CC) via plasma-enhanced atomic layer deposition (PE-ALD), then growth of the cobalt oxide (Co3O4) nanosheet arrays. The deposition cycle of FeOx on the CC strongly influences the in-situ growth and distribution of Co3O4 nanosheets and electronic conductivity of the electrocatalyst. Owing to the high accessible and electroactive areas and improved electrical conductivity, the free-standing electrode of Co3O4@FeOx/CC with 100 deposition cycles of FeOx exhibits excellent electrocatalytic performance for OER with a low overpotential of 314.0 mV at 10 mA cm−2 and a small Tafel slope of 29.2 mV dec−1 in alkaline solution, which is much better than that of Co3O4/CC (448 mV), and even commercial RuO2 (380 mV). This design and optimization strategy shows a promising way to synthesize ideally designed catalytic architectures for application in energy storage and conversion.