Mitigating Structural Degradation in Hydrated V 2 O 5 for Proton Batteries through Nanoconfinement with a Holey Graphene Matrix

Proton‐based electrochemistry offers a promising solution to the cost and safety‐limited lithium‐ion batteries in general and sluggish ion diffusion and poor stability challenges of metal‐ion batteries in particular, since it leverages the Grotthuss mechanism for ultrafast transport in aqueous media. Proton insertion accompanied by metal ions has been worked out extensively; however, pure protonation/deprotonation remains underexplored. Here, we report pure protonation/deprotonation in a confined water‐containing V 2 O 5 wrapped in holey reduced graphene oxide via facile hydrothermal and sonication processes. The as‐prepared composite demonstrated stable and efficient electrochemistry by exhibiting excellent capacity (~122 mAh g −1 @ 25 mA g −1 ) and exceptional stability (over 10 000 cycles at 1 A g −1 ) with excellent coulombic efficiencies. To our knowledge, this is the first study on pure protonation/deprotonation in V 2 O 5 , highlighting its potential in highly stable energy storage systems.