A high-energy/power and ultra-stable aqueous ammonium ion microbattery based on amorphous/crystalline dual-phase layered metal oxides

The prosperity of microelectronic systems stimulates fast development of high-performance power sources with micro/nano sizes. Considering the defects of conventional lithium-ion microbatteries, i.e. high cost, severe safety concerns as well as the unsatisfactory power delivery due to the sluggish ion transport of the organic electrolytes, novel energy storage microdevices are worth looking forward to. Here, we assemble an aqueous ammonium-ion microbattery using 2D (NH4)xV2O5 with amorphous/crystalline dual-phase nanostructure deposits on 3D nanoporous Au as anode while nanoporous Au/δ-MnO2 composite as cathode. As a result of the superb electronic/ionic conductivities as well as the large voltage window, the resultant NP Au/ac-(NH4)xV2O5//NP Au/δ-MnO2 aqueous ammonium-ion microbattery exhibits ultrahigh energy density of 0.126 Wh cm−3 with electrical powers ∼280-fold higher than commercial lithium thin-film batteries, in addition to excellent rate capability (∼84.2% capacity retention at 5–50 mV s−1 scan rates) and cycling stability (retains ∼93.3% of the initial value after 10,000 cycles at 500 mV s−1). The superb performance endows it to be promising candidate as monolithic micropower source for micro/nano portable/wearable electronics with high energy storage and power delivery demands.