Uncontrollable dendrite growth resulting from the non-uniform lithium ion (Li⁺) flux and volume expansion in lithium metal (Li) negative electrode leads to rapid performance degradation and serious safety problems of lithium metal batteries. Although N-containing functional groups in carbon materials are reported to be effective to homogenize the Li⁺ flux, the effective interaction distance between lithium ions and N-containing groups should be relatively small (down to nanometer scale) according to the Debye length law. Thus, it is necessary to carefully design the microstructure of N-containing carbon materials to make the most of their roles in regulating the Li⁺ flux. In this work, porous carbon nitride microspheres (PCNMs) with abundant nanopores have been synthesized and utilized to fabricate a uniform lithiophilic coating layer having hybrid pores of both the nano- and micrometer scales on the Cu/Li foil. Physically, the three-dimensional (3D) porous framework is favorable for absorbing volume changes and guiding Li growth. Chemically, this coating layer can render a suitable interaction distance to effectively homogenize the Li⁺ flux and contribute to establishing a robust and stable solid electrolyte interphase (SEI) layer with Li-F, Li-N, and Li-O-rich contents based on the Debye length law. Such a physical-chemical synergic regulation strategy using PCNMs can lead to dendrite-free Li plating, resulting in a low nucleation overpotential and stable Li plating/stripping cycling performance in both the Li‖Cu and the Li‖Li symmetric cells. Meanwhile, a full cell using the PCNM coated Li foil negative electrode and a LiFePO₄ positive electrode has delivered a high capacity retention of ~ 80% after more than 200 cycles at 1 C and achieved a remarkable rate capability. The pouch cell fabricated by pairing the PCNM coated Li foil negative electrode with a NCM 811 positive electrode has retained ~ 73% of the initial capacity after 150 cycles at 0.2 C.

Device level performance of aqueous halide supercapatteries fabricated with equal electrode mass of activated carbon or graphene nanoplatelets has been characterized. It was revealed that the surface oxygen groups in the graphitic structures of the nanoplatelets contributed toward a more enhanced charge storage capacity in bromide containing redox electrolytes. Moreover, the rate performance of the devices could be linked to the effect of the pore size of the carbons on the dynamics of the inactive alkali metal counterion of the redox halide salt. Additionally, the charge storage performance of aqueous halide supercapatteries with graphene nanoplatelets as the electrode material may be attributed to the combined effect of the porous structure on the dynamics of the non-active cations and a possible interaction of the Br⁻/(Br₂ + Br₃⁻) redox triple with the surface oxygen groups within the graphitic layer of the nanoplatelets. Generally, it has been shown that the surface groups and microstructure of electrode materials must be critically correlated with the redox electrolytes in the ongoing efforts to commercialize these devices.