Nanoporous CaCO3 Coatings Enabled Uniform Zn Stripping/Plating for Long-Life Zinc Rechargeable Aqueous Batteries

Zn-based batteries are safe, low cost, and environmentally friendly, as well as delivering the highest energy density of all aqueous battery systems. However, the application of Zn-based batteries is being seriously hindered by the uneven electrostripping/electroplating of Zn on the anodes, which always leads to enlarged polarization (capacity fading) or even cell shorting (low cycling stability). How a porous nano-CaCO3 coating can guide uniform and position-selected Zn stripping/plating on the nano-CaCO3-layer/Zn foil interfaces is reported here. This Zn-deposition-guiding ability is mainly ascribed to the porous nature of the nano-CaCO3-layer, since similar functionality (even though relatively inferior) is also found in Zn foils coated with porous acetylene black or nano-SiO2 layers. Furthermore, the potential application of this strategy is demonstrated in Zn vertical bar ZnSO4+MnSO4 vertical bar CNT/MnO2 rechargeable aqueous batteries. Compared with the ones with bare Zn anodes, the battery with a nano-CaCO3-coated Zn anode delivers a 42.7% higher discharge capacity (177 vs 124 mAh g(-1) at 1 A g(-1)) after 1000 cycles.