MnO-pillared graphene blocks enabling the ultrastable and ultrafast aqueous zinc ion batteries

Due to the low cost, high theoretical capacity, and environmental friendliness, manganese-based cathodes are regarded as promising alternatives for aqueous zinc ion batteries (AZIBs). However, the practicality of the zinc-manganese system is faced with great challenges, such as the inevitable structural collapse of the cathode and controversial energy storage mechanisms. Herein, we propose a novel concept of spatial deposition mechanism through the addition of MnSO₄ additives in the MnO-pillared graphene blocks (G-MnO). The covalent interface between MnO nanoparticles and multilayered graphene nanosheets can construct an in-built micro-electric field, which is beneficial for consecutive electron transfer (in both horizontal and vertical directions). On this basis, the surficial activity of MnO confined in the interlayered nano-space is greatly enhanced and provides enough spatial deposition and subsequent reaction site for MnSO₄ additives, thus firstly extending the surficial controlled process to stereoscopic space, effectively improving the electrochemical performance of AZIBs. Therefore, the assembled Zn//G-MnO battery exhibits an excellent rate capability of 281.5 mAh g⁻¹at 0.1 A g⁻¹and 106 mAh g⁻¹at 20 A g⁻¹, and impressive cycling stability (93 mAh g⁻¹ remaining after 5,000 cycles). This finding may provide a new opportunity for the rational design of surficial controlled energy storage and conversion devices.