Qingdao Energy Institute introduces different functional groups to regulate the lithium storage performance of carbon-based materials

[ Instrument R&D of Instrument Network ] Energy storage devices that use carbon materials as electrode materials exhibit the advantages of ultra-high energy storage capacity, excellent chemical stability, low cost, and excellent environment. They have potential development space in energy storage. In particular, two-dimensional carbon materials such as graphyne and graphene have highly conjugated carbon skeletons, two-dimensional layered planar structures, uniformly distributed pores and large pore structures, which can provide abundant adsorption sites for energy storage ions and The smooth migration channel has wide application prospects in the field of energy storage.

Recently, the Research Group of Carbon-based Materials and Energy Applications of Qingdao Institute of Bioenergy and Processes, Chinese Academy of Sciences found that specific functional groups can be introduced through precursor control, chemical bonding, and heat treatment to accurately regulate the energy gap and electron migration of carbon materials. Rate, interlayer spacing, crystal stacking method and specific surface area can affect the intrinsic characteristics of ion storage or migration performance, and then produce energy storage materials with better electrochemical performance.

Using graphene as an example, the researchers used chemically modified precursors to synthesize a series of graphene derivatives with different functional groups such as hydrogen, methyl and cyano groups through cross-coupling reactions. The introduction of different functional groups caused significant changes in characteristics including energy gap, interlayer spacing and microstructure, which in turn significantly affected the storage capacity of lithium-ion batteries. Compared with graphyne, hydrogen-modified graphyne and methyl-modified graphyne, the electrochemical storage capacity of cyano-modified graphyne is significantly improved. When the current density is 50 mAg-1, the reversible capacity is up to 1612 mAhg- 1. Due to its unique structure, cyano-modified graphyne is more conducive to the diffusion and transmission of lithium ions in and out of the plane, giving it very good rate performance and ultra-high stability performance.

This study provides an effective strategy for the precise adjustment of the electronic structure and properties of carbon materials, and provides theoretical basis and experimental guidance for the research of the lithium storage properties of the graphyne family and the exploration of new carbon energy storage materials.

Related results were published in "German Applied Chemistry". The research work was supported by the National Natural Science Foundation of China, the Frontier Project of the Chinese Academy of Sciences, the Key Deployment Project of the Qingdao Energy Institute, and the Shandong Natural Science Foundation.