Flexible Carbon Nanofiber Paper with a Rich Mesoporous Structure as a Free-Standing, High-Performance Anode for Excellent Lithium Storage

Pore construction is an ideal strategy for improving the energy and power density of carbon paper (CP) anodes of flexible lithium-ion batteries (LIBs). However, theoretical studies that examine the impact of varying pore sizes on specific capacities are scarce. In this research, flexible porous carbon anodes with rich meso- or micropores are prepared to reveal the relation of pore structure with Li storage capacity. The mesoporous carbon nanofiber paper (ECNFP) prepared via ZnCl2 activation exhibits a higher layer spacing and additional active sites due to defects, leading to the substantial enhancement in capacity. Its specific capacity is maintained at 440 mAh·g–1 following 100 cycles at 0.1 C and 132 mAh·g–1 after 1000 cycles at 1 C. Density functional theory (DFT) further analyzes the spacing changes in defective bilayer graphene (BLG), which result in alterations in the interaction force. The interaction repulsion of Li to the upper graphene layer disappeared as the graphene layer distance increased, and both the adsorption energy (Eads) and binding energy (Ebin) are reduced, facilitating the faster Li diffusion. This work provides theoretical guidance for optimizing pore size in porous carbon-based anode materials and establishes a promising framework for developing flexible anode materials.