Inverse-opal-structured hybrids of N, S-codoped-carbon-confined Co9S8 nanoparticles as bifunctional oxygen electrocatalyst for on-chip all-solid-state rechargeable Zn-air batteries

Through the combination of inverse-opal-structured hybrids of N, S-codoped-carbon-confined Co9S8 nanoparticles for high-efficient bifunctional electrocatalysts at air-cathode and polyacrylamide-co-polyacrylic acid alkalinous hydrogel of high ion-conductivity and water holding power for solid electrolyte, on-chip all-solid-state rechargeable Zn-air batteries (OAR-ZABs) are developed. The OAR-ZABs acquire a higher open circuit potential of 1.408 V, larger specific capacity of 738 mA h g−1, and better rechargeability (105 cycles/35 h) compared with most reported devices employing traditional PVA basic hydrogel electrolyte. The exhibited areal/specific energy densities (7.53 mW h cm−2/900.4 Wh kg−1) also outperform the values of competitors such as micro-supercapacitors (≤0.01 mW h cm−2) and Li-ion batteries (≤200 Wh kg−1). Furthermore, the reasonable in-plane electrode deployment endows the OAR-ZABs with good coplanar integration capability and high flexibility, allowing in-plane series/parallel connection to output required voltage/current and working stably at different bending angles. Combined with the other advantages including its miniaturization and the inherent security of employed hydrogel electrolyte, the OAR-ZABs are ideally suitable for wearable applications. As a demo, a flexible OAR-ZABs array in series connection is fabricated and conformally sewed on clothes, being safely used to charge the smart phone or light the safety warning device. All these make them competitive micro-power sources for wearable microelectronics.