The fundamentals related to the oxygen evolution reaction and catalyst design are summarized and discussed.

Metallic zinc anodes of aqueous zinc ion batteries suffer from severe dendrite and side reaction issues, resulting in poor cycling stability, especially at high rates and capacities. Herein, we develop two three-dimensional hierarchical graphene matrices consisting of nitrogen-doped graphene nanofibers clusters anchored on vertical graphene arrays of modified multichannel carbon. The graphene matrix with radial direction carbon channels possesses high surface area and porosity, which effectively minimizes the surface local current density, manipulates the Zn²⁺ ions concentration gradient, and homogenizes the electric field distribution to regulate Zn deposition. As a result, the engineered matrices achieve a superior coulombic efficiency of 99.67% over 3000 cycles at 120 mA cm⁻², the symmetric cells with the composite zinc anode demonstrates 2600 h dendrite-free cycles at 80 mA cm⁻² and 80 mAh cm⁻². The as-designed full cell exhibits an inspiring capacity of 16.91 mAh cm⁻². The Zn capacitor matched with activated carbon shows a superior long-term cycle performance of 20000 cycles at 40 mA cm⁻². This strategy of constructing a 3D hierarchical structure for Zn anodes may open up a new avenue for metal anodes operating under high rates and capacities.

A Ru vacancy decreases the energy barrier from O* to OOH*, thus dramatically enhancing the OER performance of defect-rich RuO₂ nanosheets.

The widespread application of aqueous rechargeable zinc ion batteries (ARZIBs) is limited by issues from both electrodes, including poor reversibility of the zinc anode and low capacity of the cathode. Here, we report the application of a Zn²⁺ substituted Nafion separator (Zn-Nafion) in ARZIBs which improves the performance of both the cathode and anode. On the anode side, the Zn-Nafion separator creates a uniform electrical and Zn²⁺ concentration field near the zinc anode surface, resulting in limited zinc dendrite growth. Therefore, a Zn symmetric cell with a Zn-Nafion separator shows a lower polarization and longer cycle life than those applying a traditional glass fiber separator. On the cathode side, the Zn-Nafion separator increases the contribution of the H⁺ reaction in the H⁺/Zn²⁺ co-insertion process, and causes the randomly distributed byproducts, Zn₄SO₄(OH)₆·nH₂O platelets, to transform into a dense solid-electrolyte-interphase layer, which protects the cathode from dissolving into the electrolyte. Thus, the energy density and capacity retention of both zinc full cells (applying commercial V₂O₅ or α-MnO₂ nanowires as the cathode) are dramatically improved by the Zn-Nafion separator. Notably, the Zn//Zn-Nafion//V₂O₅ cell delivers a high specific capacity of 495.8 mA h g⁻¹ (374.4 W h kg⁻¹) with a low cathode cost (39.23 US$ W h kg⁻¹). Moreover, the Zn-Nafion separator can be recycled at least ten times without performance degradation, which significantly reduces the cost of the battery. The present work can provide a novel insight into cost-effective and high-performance battery technologies.