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  1. Free, publicly-accessible full text available October 12, 2023
  2. null (Ed.)
    Electrochemical water splitting is one of the most promising approaches for sustainable energy conversion and storage toward a future hydrogen society. This demands durable and affordable electrocatalysts for the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER). In this study, we report the preparation of uniform Ni–P–O, Ni–S–O, and Ni–S–P–O electrocatalytic films on nickel foam (NF) substrates via flow cell-assisted electrodeposition. Remarkably, electrodeposition onto 12 cm 2 substrates was optimized by strategically varying critical parameters. The high quality and reproducibility of the materials is attributed to the use of a 3D-printed flow cell with a tailored design. Then, the as-fabricated electrodes were tested for overall water splitting in the same flow cell under alkaline conditions. The best-performing sample, NiSP/NF, required relatively low overpotentials of 93 mV for the HER and 259 mV for the OER to produce a current density of 10 mA cm −2 . Importantly, the electrodeposited films underwent oxidation into amorphous nickel (oxy)hydroxides and oxidized S and P species, improving both HER and OER performance. The superior electrocatalytic performance of the Ni–S–P–O films originates from the unique reconstruction process during the HER/OER. Furthermore, the overall water splitting test using the NiSP/NF couple required a low cell voltage of only 1.85 V to deliver a current density of 100 mA cm −2 . Overall, we demonstrate that high-quality electrocatalysts can be obtained using a simple and reproducible electrodeposition method in a robust 3D-printed flow cell. 
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  3. The performance of the rechargeable Li metal battery anode is limited by the poor ionic conductivity and poor mechanical properties of its solid-electrolyte interphase (SEI) layer. To overcome this, a 3 : 1 v/v ethyl methyl carbonate (EMC) : fluoroethylene carbonate (FEC) containing 0.8 M lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) and 0.2 M lithium difluoro(oxalate)borate (LiDFOB) dual-salts with 0.05 M lithium hexafluorophosphate (LiPF 6 ) was tested to promote the formation of a multitude of SEI-beneficial species. The resulting SEI layer was rich in LiF, Li 2 CO 3 , oligomeric and glass borates, Li 3 N, and Li 2 S, which enhanced its role as a protective yet Li + conductive film, stabilizing the lithium metal anode and minimizing dead lithium build-up. With a stable SEI, a Li/Li[Ni 0.59 Co 0.2 Mn 0.2 Al 0.01 ]O 2 Li-metal battery (LMB) retains 75% of its 177 mA h g −1 specific discharge capacity for 500 hours at a coulombic efficiency of greater than 99.3% at the fast charge–discharge rate of 1.8 mA cm −2 . 
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  4. Abstract

    The dynamic information of lithium‐ion battery active materials obtained from coin cell‐based in‐situ characterizations might not represent the properties of the active material itself because many other factors in the cell could have impacts on the cell performance. To address this problem, a single particle cell was developed to perform the in‐situ characterization without the interference of inactive materials in the battery electrode as well as the X‐ray‐induced damage. In this study, the dynamic morphological and phase changes of selenium‐doped germanium (Ge0.9Se0.1) at the single particle level were investigated via synchrotron‐based in‐situ transmission X‐ray microscopy. The results demonstrate the good reversibility of Ge0.9Se0.1at high cycling rate that helps understand its good cycling performance and rate capability. This in‐situ and operando technique based on a single particle battery cell provides an approach to understanding the dynamic electrochemical processes of battery materials during charging and discharging at the particle level.

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