Potassium-ion batteries are a compelling technology for large scale energy storage due to their low-cost and good rate performance. However, the development of potassium-ion batteries remains in its infancy, mainly hindered by the lack of suitable cathode materials. Here we show that a previously known frustrated magnet, KFeC 2 O 4 F, could serve as a stable cathode for potassium ion storage, delivering a discharge capacity of~112 mAh g −1 at 0.2 A g −1 and 94% capacity retention after 2000 cycles. The unprecedented cycling stability is attributed to the rigid framework and the presence of three channels that allow for minimized volume fluctuation when Fe 2+ /Fe 3+ redox reaction occurs. Further, pairing this KFeC 2 O 4 F cathode with a soft carbon anode yields a potassium-ion full cell with an energy density of~235 Wh kg −1 , impressive rate performance and negligible capacity decay within 200 cycles. This work sheds light on the development of low-cost and high-performance K-based energy storage devices.

Rechargeable zinc-ion batteries (RZIB) present an interesting alternative to rechargeable Li-ion batteries. Among the active materials, layered vanadium-based oxides show a poor cell voltage but modifying this structure by attaching a phosphate group to the vanadium redox center can drastically enhance the cathode voltage. With this layered VOPO4 material, we demonstrate that preintercalating polypyrrole between crystallographic layers and using electrolyte with controlled water amounts are two absolutely essential conditions for easy and reversible Zn2+ (de)­intercalation, thus vastly improving battery outputs and long-term capacity retention. We establish that the rational design of open-layered structures hinges imperatively on factors like host structural integrity and electrode–electrolyte compatibility in delivering the performance of multivalent-ion batteries.

Electrocatalysts are one of the most important parts for oxygen evolution reaction (OER) to overcome the sluggish kinetics. Herein, amorphous Fe-Ni-P-B-O (FNPBO) nanocages as efficient OER catalysts are synthesized by a simple low-cost and scalable method at room temperature. The samples are chemically stable, in clear contrast to reported unstable or even pyrophoric boride samples. The Fe/Ni ratio of the FNPBO nanocages can be continuously adjusted to optimize the OER catalytic performance. The FNPBO nanocages composed of multicomponent elements can weaken the metal-metal bonds thus rearranging the electron density around the catalytic metal atom centers and reducing the energy barrier for intermediate formation. Hence the optimized FNPBO (Fe6.4Ni16.1P12.9B4.3O60.2) catalyst shows superior intrinsic electrocatalytic activity for OER. The low overpotential to afford the current density of 10 mA cm -2 (236 mV), the small Tafel slope (39 mV dec -1 ), and the high specific current density (26.44 mA cm -2 ) at a given overpotential of 300 mV make a sharp contrast to state-of-the-art RuO2 (327 mV, 136 mV dec -1 , and 0.028 mA cm -2 , respectively). Clean energy is highly desired for clean and sustainable future. [1][2][3] Hydrogen has been considered as an ideal alternative fuel to replace gasoline, which is environmental friendly with a

Efficient bifunctional electrocatalysts for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) are required for metal air batteries, to replace costly metals, such as Pt and Ir/Ru based compounds, which are typically used as benchmarks for ORR and OER, respectively. Isolated single atomic sites coordinated with nitrogen on carbon supports (M‐N‐C) have promising performance for replacement of precious metal catalysts. However, most of monometallic M‐N‐C catalysts demonstrate unsatisfactory bifunctional performance. Herein, a facile way of preparing bimetallic Fe and Co sites entrapped in nitrogen‐doped hollow carbon nanospheres (Fe,Co‐SA/CS) is explored, drawing on the unique structure and pore characteristics of Zeolitic imidazole frameworks and molecular size of Ferrocene, an Fe containing species. Fe,Co‐SA/CS showed an ORR onset potential and half wave potential of 0.96 and 0.86 V, respectively. For OER, (Fe,Co)‐SA/CS attained its anodic current density of 10 mA cm–2 at an overpotential of 360 mV. Interestingly, the oxygen electrode activity (ΔE) for (Fe,Co)‐SA/CS and commercial Pt/C‐RuO2 is calculated to be 0.73 V, exhibiting the bifunctional catalytic activity of (Fe,Co)‐SA/CS. (Fe,Co)‐SA/CS evidenced desirable specific capacity and cyclic stability than Pt/C‐RuO2 mixture when utilized as an air cathode in a homemade Zinc‐air battery.

Sodium-based dual-ion batteries (Na-DIBs) show a promising potential for large-scale energy storage applications due to the merits of environmental friendliness and low cost. However, Na-DIBs are generally subject to poor rate capability and cycling stability for the lack of suitable anodes to accommodate large Na+ ions. Herein, we propose a molecular grafting strategy to in-situ synthesize tin pyrophosphate nanodots implanted in N-doped carbon matrix (SnP2O7@N-C), which exhibits a high fraction of active SnP2O7 up to 95.6 wt% and a low content of N-doped carbon (4.4 wt%) as the conductive framework. As a result, this anode delivers a high specific capacity ∼400 mAh g−1 at 0.1 A g−1, excellent rate capability up to 5.0 A g−1, and excellent cycling stability with a capacity retention of 92% after 1200 cycles under a current density of 1.5 A g−1. Further, pairing this anode with an environmentally friendly KS6 graphite cathode yields a SnP2O7@N-C||KS6 Na-DIB, exhibiting an excellent rate capability up to 30 C, good fast-charge/slow-discharge performance, and long-term cycling life with a capacity retention of ∼96% after 1000 cycles at 20 C. This study provides a feasible strategy to develop high-performance anodes with high-fraction active materials for Na-based energy storage applications.