Sustainable conversion of biomass waste into porous carbon with unique electronic, morphological, and chemical structures has attracted much attention in energy storage applications. Abutilon theophrasti is an annual subshrub herb of the mallow family, which grows along many country roads. Herein, N and O co-doping abutilon theophrasti stem-derived activated carbon (ATSAC) was synthesized by high-temperature carbonization and subsequent two-step activation processes, whose morphology, structure, and electrochemical performance were modulated by the KOH activation with different concentration. The optimized ATSAC-6 anode exhibits ultrahigh surface area (3783.1 m2 g–1) and micropore ratio (94%), which delivers superior specific capacitance (365.1 F g–1 at a current density of 1 A g–1), outstanding rate performance (64% retention at a high current density of 15 A g–1), and excellent cycling stability (97% retention after 6000 cycles). Furthermore, symmetric supercapacitors fabricated by two ATSAC-6 electrodes with different electrolytes (6 M KOH and [BMIM]BF4/AN) were investigated. The KOH device shows a high specific capacitance of 74.81 F g–1 at a current density of 0.25 A g–1, while the [BMIM]BF4/AN device achieves a remarkable energy density of 51.83 Wh kg–1 at a power density of 375 W kg–1.

Aqueous zinc‐ion batteries (AZIBs) have recently shown promise as prospective energy storage systems owing to their eco‐friendliness, low price, high security, and reversible storage. However, low specific capacity and the lack of cathode materials with a long life severely restrict the development of AZIBs. Herein, nanoflower‐like vanadium oxide nanoribbons are rapidly synthesized using a microwave‐assisted solvothermal method, and the layer spacing of synthesized nanoribbons is subsequently expanded with ammonium via high‐temperature calcination in an NH3 atmosphere. The increased layer spacing of vanadium oxide facilitates the intercalation/extraction of Zn2+ and accelerates the electrochemical kinetics, resulting in a highly reversible pseudocapacitive contribution (71% at a scan rate of 1 mV s−1). The ammonium‐embedded V2O5 with the carbon‐coated NH4V4O10/C (NHVO/C) cathode shows a high specific capacity (458.6 mAh g−1 at 0.1 A g−1) and excellent cycling stability (about 90% capacity retention after 2800 cycles at 10 A g−1), which is superior to most cathode materials for AZIBs. Furthermore, reversible Zn2+ intercalation/extraction in the NHVO/C cathode during electrochemical reactions is elucidated through in situ and ex situ material characterization. The findings are expected to inspire the development of advanced vanadium‐based cathode materials for green, safe, and dependable energy storage devices for commercial applications.

Lithium–sulfur batteries are promising for high-capacity energy storage, but their performance is limited by the shuttle effect and unfavorable volume changes during the charging and discharging cycles. To address these issues, we synthesized NiCo2S4 hollow dodecahedra@nitrogen-doped carbon core/shell nanostructures (NiCo2S4@NC) using the ZIF-67 template and polydopamine carbonization. The high chemical conversion rate and large specific surface area of NiCo2S4 hollow dodecahedra promote fast and stable polysulfide conversion, while the N-doped carbon shell mitigates structural collapse and volume changes caused by reversible reactions of lithium sulfides. Coupling the superior polysulfide conversion of NiCo2S4 with the excellent polysulfide adsorption of the N-doped carbon shell, NiCo2S4@NC/S (72% sulfur loading) delivers an initial specific capacity of 1170 mA h g–1 at 0.2 C, a capacity retention of 61% after 300 cycles, and a reversible specific capacity of 420 mA h g–1 after 500 cycles at a high current density of 1 C. Our results suggest that NiCo2S4@NC can serve as a promising cathode material for lithium–sulfur batteries with improved performance and stability.

The structural deformation during the embedding/de-embedding of K+ with the large ionic size is an important factor limiting the development of potassium-ion batteries (PIBs). The iron-based mixed polyanionic material Na4Fe3(PO4)2(P2O7)...