Hierarchical porous carbon with honeycomb-like structure as high-performance anode materials for lithium ion storage

Bio-based carbon materials are promising anode materials for lithium-ion storage due to their low cost, high capacity and structural designability. In this study, cork activated carbon (CAC) was synthesized using a two-step carbonization-activation method. CAC has a fluffy honeycomb structure composed of porous carbon nanosheets (100-200 nm) with an ultra-high specific surface area (SSA) of 2913.58 m2/g, maximum mesoporous volume of 1.55 cm3 g- 1, and minimum average pore size of 2.53 nm. The unique porous structure of CAC provides more active sites for the surface redox reaction, which is conducive to lithium-ion embedding and de-embedding. As an anode material, CAC exhibits super-efficient lithium-ion storage performance with high reversible specific capacity (2132.6 mAh g- 1 at 0.1 A g- 1), excellent rate performance (256.5 mAh g- 1 at 10 A g- 1), and long cycle stability (376.64 mAh g- 1 after 1000 cycles at 5 A g- 1). It was discovered that mesopores are more effective in increasing capacity, while micropores buffer the embedded lithium stress. The energy storage of CAC is based on surface control, which improves the lithium storage capacity as the specific surface area increases. A higher degree of graphitization improves the electron transport efficiency, providing a new method for constructing high-performance anodes for lithium-ion storage.