Study of nano-porous hard carbons as anode materials for lithium ion batteries

A series of hard carbons with different porous structure are prepared and tested for an anode of lithium ion batteries. Nitrogen adsorption/desorption isotherms and transmission electron microscope images reveal that the porous carbons prepared using different template exhibit typical mesoporous structure and hierarchical porous structure respectively. The results of charge–discharge tests and diffusion coefficients show that the electrochemical behavior is strongly dependent on the porous texture of carbons. The obtained hierarchical porous carbons exhibit a highest capacity of 503.5 mAh g−1 at 0.2C rate and still keep a capacity of 332.8 mAh g−1 at 5C rate. The enhanced electrode performance of the porous hard carbons derives from better structural flexibility and shorter diffusion pathways in the advantageous nano-porous texture.

► We synthesize three typical hard carbons with different pore-structure for lithium ion batteries. ► We examine the relation between pore-structure and electrochemical performances of the carbons. ► Hard carbons with hierarchical porous structure exhibit the most favorable performance. ► We investigated the electrochemical diffusion kinetics of the three carbons. ► The improved performances are due to the utilization of lithium ion diffusion in porous carbons.