Ultrahigh-energy and -power aqueous rechargeable zinc-ion microbatteries based on highly cation-compatible vanadium oxides

Abstract

• Aqueous Zn-ion microbatteries are constructed by nanoporous metal/oxide electrodes. • Cation insertion/extraction kinetics depends on host/guest compatibility. • Zn x V 2 O 5 supported by nanoporous Au shows the highest capacity and rate capability. • Zn-ion microbatteries of nanoporous Au/Zn x V 2 O 5 outperform the present microdevices. Aqueous multivalent-metal-ion intercalation chemistries hold genuine promise to develop safe and powerful microbatteries for potential use in many miniaturized electronics. However, their development is beset by state-of-the-art electrode materials having practical capacities far below their theoretical values. Here we demonstrate that high compatibility between layered transition-metal oxide hosts and hydrated cation guests substantially boost their multi-electron-redox reactions to offer higher capacities and rate capability, based on typical bipolar vanadium oxides preintercalated with hydrated cations (M x V 2 O 5 ). When seamlessly integrated on Au current microcollectors with a three-dimensional bicontinuous nanoporous architecture that offers high pathways of electron transfer and ion transport, the constituent Zn x V 2 O 5 exhibits specific capacity of as high as ∼527 mAh g −1 at 5 mV s −1 and retains ∼300 mAh g −1 at 200 mV s −1 in 1 M ZnSO 4 aqueous electrolyte, outperforming the M x V 2 O 5 (M = Li, Na, K, Mg). This allows aqueous rechargeable zinc-ion microbatteries constructed with symmetric nanoporous Zn x V 2 O 5 /Au interdigital microelectrodes as anode and cathode to show high-density energy of ∼358 mWh cm −3 (a value that is forty-fold higher than that of 4 V/500 μAh Li thin film battery) at high levels of power delivery.