Fig. 3: Electrochemical performance of aqueous Zn | |Co2P-CoP-NiCoO2 cells and perovskite solar cells.

a Voltage profiles at various specific currents for the aqueous Zn | |Co2P-CoP-NiCoO2 cell. b Capacity comparison of undoped and P-doped NiCo2O4-based Zn batteries at various specific currents. c Long-term cycling performance of the aqueous Zn | |Co2P-CoP-NiCoO2 cell at 32 A/g. d J–V profiles of HTM-free C-PVKs based on bare carbon paper and sandwich electrodes. e Current–voltage profiles of perovskite modules connected by three HTM-free C-PVKs.