Rational Construction of Self‐Standing Sulfur‐Doped Fe₂O₃ Anodes with Promoted Energy Storage Capability for Wearable Aqueous Rechargeable NiCo‐Fe Batteries

Abstract

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.

Recent Advances and Prospects of Fiber‐Shaped Rechargeable Aqueous Alkaline Batteries

“…Yang et al calculated the bandgap of Fe 2 O 3 materials, where it decreased from 2.34 to 1.18 eV after sulfur doping, resulting in improved electronic conductivity. [69] It is clearly shown in Figure 10d that the oxygen atom was partially replaced by the sulfur atom. Compared with undoped Fe 2 O 3 , the SEM image of S-Fe 2 O 3 appeared to be marginally different, with Fe 2 O 3 nanowires distributed vertically on the surface of the CNT fiber, as shown in Figure 10e.…”

“…Reproduced with permission. [69] Copyright 2020, Wiley-VCH. and numerous technical barriers persist.…”

High‐Capacity Iron‐Based Anodes for Aqueous Secondary Nickel−Iron Batteries: Recent Progress and Prospects

“…Yang et al found that the band gap was reduced from 2.34 to 1.18 eV after the sulfur doping via the first-principle calculations, thus increasing the electronic conductivity. [60] Figure 6d clearly showed that the sulfur atoms partially replace oxygen atoms. The SEM image of SÀ Fe 2 O 3 seemed slightly different compared to the un-doped Fe 2 O 3 , where the Fe 2 O 3 nanowires were almost vertically distributed on the surface of CNTF as shown in Figure 6e.…”

Intrinsic Structure Modification of Electrode Materials for Aqueous Metal‐Ion and Metal‐Air Batteries

“…[152] By contrast to other nonmetal elements, the sulfur displays much larger covalent radius, which may significantly enlarge the interlayer distance of carbon, offer additional ion storage sites and improved ion diffusion kinetics. [153] Due to the low electronegativity and high electron-donating ability, the phosphorus can be also doped into carbon materials to improve the electrochemical property. [154] As the same periodic element with carbon, the nitrogen is more likely to chemically bond with carbon, and effectively enhance the reactivity and electronic conductivity by producing extrinsic defects.…”