Summary The Ni-Fe battery is a promising alternative to lithium ion batteries due to its long life, high reliability, and eco-friendly characteristics. However, passivation and self-discharge of the iron anode are the two main issues. Here, we demonstrate that controlling the valence state of the iron and coupling with carbon can solve these problems. We develop a mesostructured carbon/Fe/FeO/Fe 3 O 4 hybrid by a one-step solid-state reaction. Experimental evidence reveals that the optimized system with three valence states of iron facilitates the redox kinetics, while the carbon layers can effectively enhance the charge transfer and suppress self-discharge. The hybrid anode exhibits high specific capacity of 604 mAh⋅g −1 at 1 A⋅g −1 and high cyclic stability. A Ni-Fe button battery is fabricated using the hybrid anode exhibits specific device energy of 127 Wh⋅kg −1 at a power density of 0.58 kW⋅kg −1 and maintains good capacity retention (90%) and coulombic efficiency (98.5%).

Aqueous zinc‐ion batteries (AZIBs) are becoming increasingly popular energy storage technology compared with conventional lithium‐ion and other rechargeable batteries. However, the poor structural stability and low conductivity remain a significant challenge in the development of the cathode material. This renders AZIBs with limitation of commercial secondary batteries. Herein, cathode optimization is demonstrated through precise control of the coupling of MnO with reduced graphene oxide (rGO) and multiwall carbon nanotubes (MWCNTs). 3D ternary MnO/rGO/MWCNTs (MPGC) nanostructures are synthesized by combining MnO nanoparticles with rGO and MWCNTs using a scalable hydrothermal and solid thermal reduction method. The MPGC cathode delivers a high specific capacity of 267.4 mAh g−1 at 0.2 A g−1 and improved stability with retention rate of 96.2% after 200 cycles at 0.5 A g−1 and 94.7% after 550 cycles at 1.2 A g−1. This simple synthesis method has great potential in practical application of AZIBs as next‐generation rechargeable batteries.

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