Flexible and Tailorable Na−CO2 Batteries Based on an All-Solid-State Polymer Electrolyte

Abstract

Rechargeable Na< C->CO2 batteries coupling Na anodes with the greenhouse gas CO2 cathode are promising energy-storage devices due to the high energy density, environmental friendliness and cost-effectiveness. However, major challenges impeding the application of Na−CO2 batteries are safety concern regarding the leakage of flammable liquid electrolytes and the instability of the Na anodes. Herein, we construct all-solid-state flexible Na−CO2 batteries by designing an integrated structure built of a Na anode, poly(ethylene oxide)/NaClO4/SiO2 electrolyte and multiwall carbon nanotubes cathode. The batteries exhibit much improved safety and good cyclability (240 cycles with an overpotential increase of ∼0.4 V). Remarkably, we fabricated lab scale-up integrated batteries (8×16 cm2), which display large capacity (450 mAh) and high energy density (173 Wh kg−1). Moreover, the integrated batteries show excellent bendability (≥1,000 times), foldability in individual shapes, as well as stable operation time (80 h) at bending states of 0° to 360°. Our work demonstrates a way to exploit flexible and safe solid-state Na−CO2 batteries.