HIU Seminar | Prof. Chi-Chang Hu
Prof. Chi-Chang Hu will be guest during the upcoming HIU Seminar taking place on Monday, 17th October 2025 at 4:00 pm: The talk will be held in person in the large seminar room (230) at the HIU and streamed under the usual Zoom link: The title of the talk will be “Microstructure Designs of Hard Carbons to Promote the Lithium-ion Storage Capacity".
Abstract
Novel phenolic-formaldehyde resin-derived hard carbon (HC) prepared by the suspension polymerization is investigated for Li-ion storage of high capacity. By N2, O2, and CO2 adsorption/desorption isotherms, the open/closed porosity in HCs is successfully distinguished and quantified. Through in-depth explorations, the Li-ion storage mechanism in HCs with various open/closed porosity has been carefully elucidated. In particular, the closed ultramicropores < 0.7 nm are termed as ‘’active closed pores’’ because they can facilitate the insertion of de-solvated Li ions and mitigate substantial initial irreversible capacity by blocking the penetration of solvents. The HC with abundant active closed pores can deliver a reversible capacity of 550 mAh g-1 at 50 mA g-1 in 0.001-1.5 V, with a plateau capacity of 230 mAh g-1 at potentials close to the redox potential of Li+/Li, contributed by the Li-ion insertion in active closed pores. The excellent rate capability and cycling stability of this HC have been confirmed via a series of tests.[1]
In the second part, a novolak resin precursor with controllable cross-linking density (CLD) is used to fabricate HCs. By varying the catalysts, the binding position among oligomers shifts from random distributions to mostly ortho sites. Contemporary material analyses reveal that low-CLD precursors tend to form pseudo-graphitic layers at early stage, generating abundant closed pores under suitable carbonization condition. A well correlation between Li-ion plateau capacity and closed pore volume along with in-situ XRD and Raman analyses confirms that low-potential plateau results from Li+ filling into closed pores in these HCs. Consequently, the best HC achieves a reversible capacity of 550 mAh g⁻1, including nearly 50% plateau capacity (255 mAh g⁻1). This work provides comprehensive understanding in closed pore engineering and the origin of low-potential plateau, a promising route for microstructural engineering toward high-performance LIBs/LICs.[2]