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Photo‐rechargeable zinc‐ion batteries (PRZIBs) have attracted much attention in the field of energy storage due to their high safety and dexterity compared with currently integrated lithium‐ion batteries and solar cells. However, challenges remain toward their practical applications, originating from the unsatisfactory structural design of photocathodes, which results in low photoelectric conversion efficiency (PCE). Herein, a flexible MoS2/SnO2‐based photocathode is developed via constructing a sunflower‐shaped light‐trapping nanostructure with 3D hierarchical and self‐supporting properties, enabled by the hierarchical embellishment of MoS2 nanosheets and SnO2 quantum dots on carbon cloth (MoS2/SnO2 QDs@CC). This structural design provides a favorable pathway for the effective separation of photogenerated electron‐hole pairs and the efficient storage of Zn2+ on photocathodes. Consequently, the PRZIB assembled with MoS2/SnO2 QDs@CC delivers a desirable capacity of 366 mAh g−1 under a light intensity of 100 mW cm−2, and achieves an ultra‐high PCE of 2.7% at a current density of 0.125 mA cm−2. In practice, an integrated battery system consisting of four series‐connected quasi‐solid‐state PRZIBs is successfully applied as a wearable wristband of smartwatches, which opens a new door for the application of PRZIBs in next‐generation flexible energy storage devices. [ABSTRACT FROM AUTHOR]

A novel composite of iron sulfide, iron carbide and nitrogen carbides (Nano-FeS/Fe3C@NCNTs) as a cathode electrocatalyst for microbial fuel cells (MFCs) is synthesized by a one-pot solid state reaction, which yields a unique configuration of FeS/Fe3C nanoparticles highly dispersed on in situ grown nitrogen-doped carbon nanotubes (NCNTs). The highly dispersed FeS/Fe3C nanoparticles possess large active sites, while the NCNTs provide an electronically conductive network. Consequently, the resultant Nano-FeS/Fe3C@NCNTs exhibit excellent electrocatalytic activity towards the oxygen reduction reaction (ORR), with a half-wave potential close to that of Pt/C (about 0.88 V vs. RHE), and enable MFCs to deliver a power density of 1.28 W m−2 after two weeks' operation, which is higher than that of MFCs with Pt/C as the cathode electrocatalyst (1.02 W m−2). Theoretical calculations and experimental data demonstrate that there is a synergistic effect between Fe3C and FeS in Nano-FeS/Fe3C@NCNTs. Fe3C presents a strong attraction and electron-donating tendency to oxygen molecules, serving as the main active component, while FeS reduces charge transfer resistance by transferring electrons to Fe3C, synergistically improving the kinetics of the ORR and power density of MFCs. [ABSTRACT FROM AUTHOR]

All‐solid‐state zinc–air batteries are characterized as low cost and have high energy density, providing wearable devices with an ideal power source. However, the sluggish oxygen reduction and evolution reactions in air cathodes are obstacles to its flexible and rechargeable application. Herein, a strategy called MOF‐on‐MOF (MOF, metal‐organic framework) is presented for the structural design of air cathodes, which creatively develops an efficient oxygen catalyst comprising hierarchical Co3O4 nanoparticles anchored in nitrogen‐doped carbon nano‐micro arrays on flexible carbon cloth (Co3O4@N‐CNMAs/CC). This hierarchical and free‐standing structure design guarantees high catalyst loading on air cathodes with multiple electrocatalytic activity sites, undoubtedly boosting reaction kinetics, and energy density of an all‐solid‐state zinc–air battery. The integrated Co3O4@N‐CNMAs/CC cathode in an all‐solid‐state zinc–air battery exhibits a high open circuit potential of 1.461 V, a high capacity of 815 mAh g−1 Zn at 1 mA cm−2, a high energy density of 1010 Wh kg−1 Zn, excellent cycling stability as well as outstanding mechanical flexibility, significantly outperforming the Pt/C‐based cathode. This work opens a new door for the practical applications of rechargeable zinc–air batteries in wearable electronic devices. [ABSTRACT FROM AUTHOR]

Photo-rechargeable zinc-ion batteries (PRZIBs) have attracted much attention in the field of energy storage due to their high safety and dexterity compared with currently integrated lithium-ion batteries and solar cells. However, challenges remain toward their practical applications, originating from the unsatisfactory structural design of photocathodes, which results in low photoelectric conversion efficiency (PCE). Herein, a flexible MoS 2 /SnO 2 -based photocathode is developed via constructing a sunflower-shaped light-trapping nanostructure with 3D hierarchical and self-supporting properties, enabled by the hierarchical embellishment of MoS 2 nanosheets and SnO 2 quantum dots on carbon cloth (MoS 2 /SnO 2 QDs@CC). This structural design provides a favorable pathway for the effective separation of photogenerated electron-hole pairs and the efficient storage of Zn 2+ on photocathodes. Consequently, the PRZIB assembled with MoS 2 /SnO 2 QDs@CC delivers a desirable capacity of 366 mAh g -1 under a light intensity of 100 mW cm -2 , and achieves an ultra-high PCE of 2.7% at a current density of 0.125 mA cm -2 . In practice, an integrated battery system consisting of four series-connected quasi-solid-state PRZIBs is successfully applied as a wearable wristband of smartwatches, which opens a new door for the application of PRZIBs in next-generation flexible energy storage devices., (© 2024 The Authors. Advanced Science published by Wiley‐VCH GmbH.)

A novel composite of iron sulfide, iron carbide and nitrogen carbides (Nano-FeS/Fe 3 C@NCNTs) as a cathode electrocatalyst for microbial fuel cells (MFCs) is synthesized by a one-pot solid state reaction, which yields a unique configuration of FeS/Fe 3 C nanoparticles highly dispersed on in situ grown nitrogen-doped carbon nanotubes (NCNTs). The highly dispersed FeS/Fe 3 C nanoparticles possess large active sites, while the NCNTs provide an electronically conductive network. Consequently, the resultant Nano-FeS/Fe 3 C@NCNTs exhibit excellent electrocatalytic activity towards the oxygen reduction reaction (ORR), with a half-wave potential close to that of Pt/C (about 0.88 V vs. RHE), and enable MFCs to deliver a power density of 1.28 W m -2 after two weeks' operation, which is higher than that of MFCs with Pt/C as the cathode electrocatalyst (1.02 W m -2 ). Theoretical calculations and experimental data demonstrate that there is a synergistic effect between Fe 3 C and FeS in Nano-FeS/Fe 3 C@NCNTs. Fe 3 C presents a strong attraction and electron-donating tendency to oxygen molecules, serving as the main active component, while FeS reduces charge transfer resistance by transferring electrons to Fe 3 C, synergistically improving the kinetics of the ORR and power density of MFCs.

Nitriles have been successfully used as electrolyte additives for performance improvement of commercialized lithium-ion batteries based on the LiCoO 2 cathode, but the underlying mechanism is unclear. In this work, we present an insight into the contribution of nitriles via experimental and theoretical investigations, taking for example succinonitrile. It is found that succinonitrile can be oxidized together with PF 6 - preferentially on LiCoO 2 compared to the solvents in the electrolyte, making it possible to avoid the formation of hydrogen fluoride from the electrolyte oxidation decomposition, which is detrimental to the LiCoO 2 cathode. Additionally, inorganic LiF and -NH group-containing polymers are formed from the preferential oxidation of succinonitrile, constructing a protective interphase on LiCoO 2 , which suppresses electrolyte oxidation decomposition and prevents LiCoO 2 from structural deterioration. Consequently, the LiCoO 2 cathode presents excellent stability under cycling and storing at high voltages.