Directly grown nanostructured electrodes for high-power and high-stability alkaline nickel/bismuth batteries

Bismuth oxide (Bi2O3) has received great attention as an anode material for alkaline nickel/bismuth (Ni/Bi) batteries due to its high theoretical capacity and easy preparation. However, the generally poor conductivity of metal oxides and the instability of Bi2O3 during cycling severely limit the device performance. Herein, we present the use of directly grown Bi2O3 nanoflake film with kinetic advantages as the anode for Ni/Bi batteries. Particularly, glucose-derived carbon is integrated onto the surfaces of nanoflakes, which not only enhances the electron transfer but also buffers the conversion-reaction induced volume expansion of Bi2O3, helping maintaining the cycling stability of the film. The resulting Bi2O3@C electrode exhibits high specific capacity, excellent rate performance (can be charged within 6.7 s), and good cycle stability (similar to 1,200 times; fading rate of only 0.011% per cycle). When assembled with a nickel oxide (NiO) nanosheet array cathode in basic electrolyte, a fully binder-free Ni/Bi battery is obtained, which delivers maximum energy and power densities of 34.29 W h kg(-1) and 12,159.8 W kg(-1), respectively, and good cycling performance. The power density is even much superior to that of many hybrid/asymmetric supercapacitors. Our work suggests a new generation of thin-film Ni/Bi batteries for potential high-power electronic applications.