In-situ formation of ultrafine ZnMn2O4-MnOOH composite nanoparticles embedded into porous carbon nanospheres for stable aqueous zinc-ion batteries

Rechargeable aqueous zinc ion batteries (ZIBs) have become a research hotspot among various energy storage devices because of their low cost and high safety. However, in view of the severe volume expansion from the cathode materials, ZIBs suffer from unpleasant capacity degradation. In this paper, we report the ultrafine ZnOMnO composite nanoparticles embedded into porous carbon nanospheres as a composite cathode material. After the in-situ aging process, the ZnMn2O4-MnOOH/C NSs (ZMO-MOH/C NSs) in situ generated from ZnO-MnO/C NSs with ultrafine structure and porous conductive carbon framework show the short diffusion path of Zn2+ and improve the conductivity of the material. More importantly, the ZMO-MOH/C NSs undergo a gradient expansion process in the electrochemical reaction, which further limits the severe volume expansion to ensure the integrity of the whole particles. As expected, the ZMO-MOH/C NSs cathode delivers a high discharge capacity of 336.7 mAh g(-1) at 100 mA g(-1) and features long-term stability with a capacity loss of 20.9% after 1000 cycles at 1000 mA g(-1). Besides, the assembled flexible soft-packaged batteries perform well in different bending states, indicating the potential application in portable and wearable electronic devices.