Bismuth oxide can store energy electrochemically in seventeen aqueous metal ion electrolytes with high capacity based on a “quasi-conversion reaction”.

No abstract

The practical application of iron oxide anode in rechargeable alkaline batteries is greatly hampered by the poor electrochemical stability and low rate capability. In addition, flexible solid‐state iron anode‐based rechargeable batteries with distinctive counter electrode coupling are quite lacking. Herein, an interesting “carbon glue” penetration strategy toward Fe3O4 nanorod film anode is proposed. This design not only immobilizes the nanorods and maintains strong adhesion with the current collector but also ensures continuous electrically conductive pathway, resulting in dramatically increased stability (≈99% capacity retention after 1000 cycles) and excellent rate performance (1.2 min charging with ≈70.6% initial capacity kept). By pairing with a new‐type Ni0.49Cu0.51O nanowire array cathode, a unique 1.2 V flexible rechargeable nickel–copper//iron alkaline battery is further assembled, which stores energy based on redox electrochemistry of transition metal ions. It delivers high volumetric energy and power densities (7.21 mWh cm−3; 299.30 mW cm−3), and demonstrates outstanding stability up to 5000 cycles. In particular, with the utilization of quasi‐solid‐state electrolyte, the device still maintains good performance upon substantially bending and twisting. This work presents a new concept to design high stability iron anode‐based alkaline batteries and further pushes forward the development of emerging flexible energy storage systems.

A homogenous MoO2 and carbon mixed coating on an Fe3O4 anode with a core–shell structure boosts the cycling stability and capacity of an iron oxide anode.