Fully Printed and Sweat-Activated Micro-Batteries with Lattice-Match Zn/MoS₂ Anode for Long-Duration Wearables

Aqueous zinc-ion batteries with superior operational safety have great promise to serve as wearable energy storage devices. However, the poor cycling stability and low output voltage limited their practical applications. Here, fully printable Zn/MoS₂-MnO₂ micro-batteries are developed and demonstrated significantly enhanced cycling stability with sweat activation. 2D MoS₂ is utilized to enable lattice-matching with Zn powders to realize printed Zn anodes with desirable stability and promote electron/ion transfer. Interestingly, the mild acid epidermal sweat also contributed to eliminating the MnO₂ cathode by-products and compensating for the hydrogel electrolytes' water loss. The Zn/MoS₂-MnO₂ micro-batteries achieve a high specific capacity of 318.9 µAh cm^-2 at the current density of 0.16 mA cm^-2, and an energy density of 424.6 µWh cm^-2, with remarkable cycle stability of ≈90% after 250 cycles. In-battery electrochromic display of capacity level and feasible electronics charging are demonstrated. The as-printed micro-batteries with innovative sweat activation would inspire the advances of sustainable power supply for wearables.