Dual reaction strategy for in-situ conductivity enhancement to enable high-performing aqueous zinc-based micro-batteries

Micro-batteries are promising candidates for powering various intelligent integrated applications. However, they typically rely on a single-cell reaction during charging and discharging cycles, limiting improvements in capacity and energy density. Here, we show an in situ conductivity enhancement-assisted double-cell reaction strategy to design high-performance Zn | |Bi₂O₃@Ag₂O micro-batteries that integrate two sequential electrochemical reactions within a single microdevice. Unlike simply combining Zn | |Ag₂O and Zn | |Bi₂O₃ micro-batteries, this strategy leverages the in situ conductivity enhancement effect from the Ag₂O conversion reaction in the first step to significantly boost the discharge capacity (an almost order-of-magnitude improvement compared to Zn | |Bi₂O₃ micro-batteries alone) of the second conversion reaction, resulting in a total capacity 2.1 times the combined discharge capacities of the two individual micro-batteries. Consequently, the constructed microdevice achieves a high energy density of about 19000 μWh cm^-2 and the microdevice also exhibits a micro-supercapacitor-level or higher power density (above 23000 μW cm^-2). This work challenges conventional micro-battery configurations and offers a strategy for constructing high-performance micro-power sources for intelligent integrated electronics.