Synthesis of V<sub>2</sub>O<sub>5</sub> Nanoribbon–Reduced Graphene Oxide Hybrids as Stable Aqueous Zinc-Ion Battery Cathodes via Divalent Transition Metal Cation-Mediated Coprecipitation
K. Muthukumar, Sabari Rajendran, Archana Sekar, Ya Chen, Jun Li
Abstract
Aqueous zinc-ion batteries (AZIBs) are an emerging sustainable and safer technology for large-scale electrical energy storage. Here, we report the synthesis of hybrid materials consisting of V 2 O 5 nanoribbons (NRs) and reduced graphene oxide (rGO) nanosheets as AZIB cathode materials by divalent metal cation-mediated coprecipitation. The divalent metal ions M 2+ (Zn 2+ and Mn 2+ ) effectively neutralize the negative charges on the surface of microwave-exfoliated crystalline V 2 O 5 NRs and graphene oxide (GO) nanosheets to form a strongly bound assembly. After thermal annealing in a nitrogen atmosphere, GO is converted into rGO with higher electrical conductivity while the layers in V 2 O 5 NRs are expanded by M 2+ intercalation. When only Zn 2+ ions are used during coprecipitation, the produced Zn-V 2 O 5 NR/rGO hybrid shows a very high reversible specific capacity of ∼395 mAh g –1 at 0.50 A g –1 but suffers from poor stability. This is improved by mixing Mn 2+ with Zn 2+ ions during coprecipitation. The (Mn + Zn)-V 2 O 5 NR/rGO hybrid shows a slightly lower specific capacity of ∼291 mAh g –1 at 0.5 A g –1 but a substantially improved long-cycling stability and better rate performance due to the stronger binding of Mn atoms in the V 2 O 5 host that serve as stable pillars to support the expanded V 2 O 5 layers.