The limited lithium-ion diffusion and depressed cathode/electrolyte interface stability greatly deteriorate the cycling and rate performance of lithium-ion batteries, especially when they are operated at elevated temperatures (≥50 °C) and/or high charge cutoff voltages (>4.4 V vs Li/Li+). Herein, we proposed a demand-oriented surface coating strategy by introducing multifunctional LiBO2/LiAlO2 layers onto the surface of LiNi0.5Co0.2Mn0.3O2 (NCM) single crystals, in which the middle LiAlO2 layer is designed to ensure intimate contact with NCM to prevent the direct contact between the cathode and electrolyte and thus strengthen the cathode surface structure. The outmost LiBO2 is expected to serve as an isolation layer to improve the Li+ transportation and solid electrolyte interface stability. LiBO2/LiAlO2 (BA-NCM)- and LiBO2 (B-NCM)-coated NCM were demonstrated and systematically studied by several experimental techniques. Benefiting from the demand-oriented coating strategy, BA-NCM shows the much-improved rate and cycling performances as compared with B-NCM and bare NCM at both 25 and 55 °C. Especially, when operated at 55 °C, the capacity retention of BA-NCM after 500 cycles at 1 C is as high as 66.3%, while it is 26.9% for B-NCM.

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The sluggish kinetics of both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) generate the large overpotential in water electrolysis and thus high-cost hydrogen production. Here, multidimensional nanoporous interpenetrating-phase FeNiZn alloy and FeNi3 intermetallic heterostructure is in situ constructed on NiFe foam (FeNiZn/FeNi3@NiFe) by dealloying protocol. Coupling with the eminent synergism among specific constituents and the highly efficient mass transport from integrated porous backbone, FeNiZn/FeNi3@NiFe depicts exceptional bifunctional activities for water splitting with extremely low overpotentials toward OER and HER (η1000 = 367/245 mV) as well as the robust durability during the 400 h testing in alkaline solution. The as-built water electrolyzer with FeNiZn/FeNi3@NiFe as both anode and cathode exhibits record-high performances for sustainable hydrogen output in terms of much lower cell voltage of 1.759 and 1.919 V to deliver the current density of 500 and 1000 mA cm−2 as well long working lives. Density functional theory calculations disclose that the interface interaction between FeNiZn alloy and FeNi3 intermetallic generates the modulated electron structure state and optimized intermediate chemisorption, thus diminishing the energy barriers for hydrogen production in water splitting. With the merits of fine performances, scalable fabrication, and low cost, FeNiZn/FeNi3@NiFe holds prospective application potential as the bifunctional electrocatalyst for water splitting."Image missing"