High-effective preparation of 3D hierarchical nanoporous interpenetrating network structure carbon membranes as flexible free-standing anodes for stable lithium and sodium storage

Ideal lithium/sodium storage requires a simple and effective design of carbon-based anodes with appropriate morphologies/microstructures and excellent flexibility. Herein, an advanced flexible interpenetrating network carbon membrane with 3D hierarchical nanopore structure is designed and fabricated inspired by porous membrane technology via nonsolvent induced phase separation (NIPS) and carbonization. The interpenetrating network structure in the carbon membrane is generated by the NIPS membrane formation process, while the 3D hierarchical nano-porous structure is obtained from polymer decomposition during carbonization. The unique synergistic effect between the even interpenetrating network structure and the developed 3D hierarchical porous structure not only ensured structural integrity of the anodes and provided a high-volume ion transmission reservoir, but also endowed carbon membranes with multiple active sites for energy storage. As flexible anodes, the resulting carbon membranes achieved enhanced electrochemical properties by showing maximum reversible capacitance of 351.8 mA h g(-1) in lithium storage and 237.4 mA h g(-1) in SIBs at a current density of 50 mA g(-1). In both LIBs and SIBs, the carbon membranes exhibit outstanding rate performance even at a high current density of 2000 mA g(-1). They also show excellent long-term cycling stability with the coulomb efficiency maintained nearly 100 % after the first few cycles. Therefore, this work provides a simple and high-effective cross-disciplinary approach through membrane technology and carbon materials for the production of highperformance, low-cost carbon membranes for large-scale application anodes.

Automated summary

The study introduces a flexible carbon membrane with a 3D hierarchical nanopore structure and an interpenetrating network design, providing high structural integrity, high-volume ion transmission reservoir, and multiple active sites for energy storage. The carbon membranes demonstrate enhanced electrochemical properties and outstanding rate performance in both lithium and sodium ion batteries, showcasing excellent long-term cycling stability.