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The discovery of mechanically soft solid‐state materials with fast Mg‐ion conduction is crucial for the development of solid‐state magnesium batteries. In this paper, novel magnesium gallium halide compounds are reported that achieve high ionic conductivity of 0.47 mS cm−1 at room temperature. These Mg‐ion conductors obtained by ball milling Mg and Ga salts exhibit clay‐like mechanical properties, enabling intimate contact at the electrode–electrolyte interface during battery cycling. With a combination of experimental and computational analysis, this study identifies that the soft‐clay formation is induced by partial anion exchange during milling. This partial anion exchange creates undercoordinated magnesium ions in a chlorine‐rich environment, yielding fast Mg‐ion conduction. This work demonstrates the potential of clay‐like halide electrolytes for all‐solid‐state magnesium batteries, with possible further extension to other multivalent battery systems. [ABSTRACT FROM AUTHOR]

The corrected figures are shown below, GLO:BDBC/15apr21:aenm202100296-fig-0001.jpg PHOTO (COLOR): 3 f) CV data for the electrodes containing S-Fe2O3, Fe2O3, and initial CNTF at 10 mV s-1 scan rate. gl GLO:BDBC/15apr21:aenm202100296-fig-0002.jpg PHOTO (COLOR): 4 a) CV curves for the S-Fe2O3/CNTF electrodes at various scan rates. d) GCD curves for the S-Fe2O3/CNTF electrodes. gl GLO:BDBC/15apr21:aenm202100296-fig-0003.jpg PHOTO (COLOR): 5 g) Comparative GCD curves of Ni(OH)2, ZNCO, and ZNCO@Ni(OH)2 electrodes at 4 mA cm-2. h) CV curves for the Ni(OH)2, ZNCO and ZNCO@Ni(OH)2 electrodes at various scan rates. i) GCD curves of the ZNCO@Ni(OH)2 electrode at various current densities. gl GLO:BDBC/15apr21:aenm202100296-fig-0004.jpg PHOTO (COLOR): 6 b) CV curves for the S-Fe2O3 NWAs/CNTF-based anode and ZNCO@Ni(OH)2 NWAs/CNTF-based cathode collected using a three-electrode system. gl GLO:BDBC/15apr21:aenm202100296-fig-0005.jpg PHOTO (COLOR): S7 a) CV curves and (b) GCD profiles of initial CNTF electrode anode. gl GLO:BDBC/15apr21:aenm202100296-fig-0006.jpg PHOTO (COLOR): S8 a) CV and (b) GCD curves of Fe2O3 NWAs/CNTF electrode. gl GLO:BDBC/15apr21:aenm202100296-fig-0007.jpg PHOTO (COLOR): S10 a) Charge-discharge curves of the S-Fe2O3 NWAs under different current densities. gl GLO:BDBC/15apr21:aenm202100296-fig-0008.jpg PHOTO (COLOR): S17 a) CV curves and (b) GCD curves of initial CNTF cathode. gl GLO:BDBC/15apr21:aenm202100296-fig-0009.jpg PHOTO (COLOR): S18 a) CV and (b) GCD curves of ZNCO NWAs/CNTF electrode. gl GLO:BDBC/15apr21:aenm202100296-fig-0010.jpg PHOTO (COLOR): S19 a) CV and (b) GCD curves of Ni(OH)2/CNTF electrode. gl GLO:BDBC/15apr21:aenm202100296-fig-0011.jpg PHOTO (COLOR): S22 a) Charge-discharge curves of the ZNCO@Ni(OH)2 NWAs at different current densities. gl The authors apologize for any inconvenience caused. [Extracted from the article]

Aqueous rechargeable Ni‐Fe batteries featuring an ultra‐flat discharge plateau, low cost, and outstanding safety characteristics show promising prospects for application in wearable energy storage. In particular, fiber‐shaped Ni‐Fe batteries will enable textile‐based energy supply for wearable electronics. However, the development of fiber‐shaped Ni‐Fe batteries is currently challenged by the performance of fibrous Fe‐based anode materials. In this context, this study describes the fabrication of sulfur‐doped Fe2O3 nanowire arrays (S‐Fe2O3 NWAs) grown on carbon nanotube fibers (CNTFs) as an innovative anode material (S‐Fe2O3 NWAs/CNTF). Encouragingly, first‐principle calculations reveal that S‐doping in Fe2O3 can dramatically reduce the band gap from 2.34 to 1.18 eV and thus enhance electronic conductivity. The novel developed S‐Fe2O3 NWAs/CNTF electrode is further demonstrated to deliver a very high capacity of 0.81 mAh cm−2 at 4 mA cm−2. This value is almost sixfold higher than that of the pristine Fe2O3 NWAs/CNTF electrode. When a cathode containing zinc‐nickel‐cobalt oxide (ZNCO)@Ni(OH)2 NWAs heterostructures is used, 0.46 mAh cm−2 capacity and 67.32 mWh cm−3 energy density are obtained for quasi‐solid‐state fiber‐shaped NiCo‐Fe batteries, which outperform most state‐of‐the‐art fiber‐shaped aqueous rechargeable batteries. These findings offer an innovative and feasible route to design high‐performance Fe‐based anodes and may inspire new development for the next‐generation wearable Ni‐Fe batteries. [ABSTRACT FROM AUTHOR]