Fiber supercapacitors have aroused great interest in the field of portable and wearable electronic devices. However, the restrained surface area of fibers and limited reaction kinetics of active materials are unfavorable for performance enhancement. Herein, an efficient multicomponent hierarchical structure is constructed by integrating the Cu-doped cobalt copper carbonate hydroxide@nickel cobalt layered double hydroxide (CCCH@NiCo-LDH) coreshell nanowire arrays (NWAs) on Cu fibers with highly conductive Au-modified CuO nanosheets (CCCH@NiCo-LDH NWAs@Au-CuO/Cu) via a novel in situ corrosion growth method. This multicomponent hierarchical structure contributes to a large accessible surface area, which results in sufficient permeation of the electrolyte. The Cu dopant could reduce the work function and facilitate fast charge transfer kinetics. Therefore, the effective ion diffusion and electron conduction will facilitate the electrochemical reaction kinetics of the electrode. Benefiting from this unique structure, the electrode delivers a high specific capacitance (1.97 F cm −2 /1237 F g −1 /193.3 mAh g −1 ) and cycling stability (90.8% after 30 000 cycles), exhibiting superb performance compared with most oxide-based fiber electrodes. Furthermore, the hybrid fiber supercapacitor of CCCH@NiCo-LDH NWAs@Au-CuO/Cu//VN/carbon fibers is fabricated, providing a remarkable maximal energy density of 34.97 Wh kg −1 and a power density of 13.86 kW kg −1 , exhibiting a great potential in highperformance fiber-shape energy-related systems.

The practical application of the lithium–sulfur (Li–S) battery is seriously restricted by its shuttle effect, low conductivity, and low sulfur loading. Herein, first‐principles calculations are conducted to verify that the introduction of oxygen vacancies in TiO2 not only enhances polysulfide adsorption but also greatly improves the catalytic ability and both the ion and electron conductivities. A commercial polypropylene (PP) separator decorated with TiO2 nanosheets with oxygen vacancies (OVs‐TiO2@PP) is fabricated as a strong polysulfide barrier for the Li–S battery. The thickness of the OVs‐TiO2 modification layer is only 500 nm with a low areal mass of around 0.12 mg cm−2, which enhances the fast lithium‐ion penetration and the high energy density of the whole cell. As a result, the cell with the OVs‐TiO2@PP separator exhibits a stable electrochemical behavior at 2.0 C over 500 cycles, even under a high sulfur loading of 7.1 mg cm−2, and an areal capacity of 5.83 mAh cm−2 remains after 100 cycles. The proposed strategy of engineering oxygen vacancies is expected to have wide applications in Li–S batteries.

Anchoring platinum catalysts on appropriate supports, e.g., MXenes, is a feasible pathway to achieve a desirable anode for direct methanol fuel cells. The authentic performance of Pt is often hindered by the occupancy and poisoning of active sites, weak interaction between Pt and supports, and the dissolution of Pt. Herein, we construct three-dimensional (3D) crumpled Ti 3 C 2 T x MXene balls with abundant Ti vacancies for Pt confinement via a spray-drying process. The as-prepared Pt clusters/Ti 3 C 2 T x (Ptc/Ti 3 C 2 T x ) show enhanced electrocatalytic methanol oxidation reaction (MOR) activity, including a relatively low overpotential, high tolerance to CO poisoning, and ultrahigh stability. Specifically, it achieves a high mass activity of up to 7.32 A mg Pt −1 , which is the highest value reported to date in Pt-based electrocatalysts, and 42% of the current density is retained on Ptc/Ti 3 C 2 T x even after the 3000 min operative time. In situ spectroscopy and theoretical calculations reveal that an electric field-induced repulsion on the Ptc/Ti 3 C 2 T x interface accelerates the combination of OH − and CO adsorption intermediates (CO ads ) in kinetics and thermodynamics. Besides, this Ptc/Ti 3 C 2 T x also efficiently electrocatalyze ethanol, ethylene glycol, and glycerol oxidation reactions with comparable activity and stability to commercial Pt/C.

On-chip microbatteries have attracted growing attention due to their great feasibility for integration with miniaturized electronic devices. Nevertheless, it is difficult to get both high energy/power densities in microbatteries. An increase in the thickness of microelectrodes may help to boost the areal energy density of device, yet it often leads to terrible sacrifice in its power density due to the longer electron and ion diffusion distances. In this work, a quasi-solid-state on-chip Ni-Zn microbattery is designed based on a hierarchical ordered porous (HOP) Ni@Ni(OH) 2 microelectrode, which is developed by an in situ anodizing strategy. The fabricated microelectrode can optimize ion and electron transport simultaneously due to its interconnected ordered macropore-mesopore network and high electron conductivity. As the thickness of microelectrode increases, the areal energy density of HOP Ni@ Ni(OH) 2 microelectrode shows an ascending trend with negligible sacrifice in power density and rate performance. Impressively, this Ni-Zn microbattery achieves excellent energy/power densities (0.26 mW h cm −2 , 33.8 mW cm −2 ), outperforming most previous reported microenergy storage devices. This study may provide new direction in high-performance and highly safe microenergy storage units for next-generation highly integrated microelectronics.

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