Controllable C-N site assisting observable potential difference for homogeneous copper deposition in aqueous Cu-S batteries

Aqueous Cu-S battery with four-electron sulfur reaction has been born on the basis of thermodynamic and dynamical feasibility. It inherits the intrinsic merit of low lost, low toxicity and low energy consumption for recycling and delivers the theoretical capacity of 3350 mAh g−1 (based on the mass of sulfur) while its further development is restrained by copper-dendrite. We firstly take actions to protect Cu metal anode from dendrite guaranteeing the sustainability of delivering high capacity. Concretely, we apply three-dimensional carbon paper as substrate and then creatively introduce polyacrylonitrile on its surface to generate controllable C-N affinity coupling sites as verified by density functional theory. These active sites bring observable potential difference on carbon paper boosting uniform distribution of electric field and dendrite-free copper deposition. Applying this material as anode, aqueous Cu-S battery can achieve a discharge specific capacity of 2745.9 mAh g−1 at 10 A g−1 and still maintain the reversible capacity of 1303.3 mAh g−1 after 1200 cycles.