Stable fast-charging electrodes derived from hierarchical porous carbon for lithium-ion batteries

Abstract

Lithium-ion batteries (LIBs) have been widely used for powering electric vehicles (EVs), however, the charging time of LIBs is considerably higher than the refueling time of petrol-fueled vehicles, which limits the applications of LIBs. Materials that can overcome this limitation should be developed, and these materials should be inexpensive to commercialize. In this study, activated carbon (AC) was used as an anode material in LIB to satisfy both the requirements. The surface and pore structure of commercial AC was suitably modified for fast charging using physical and chemical activation methods, that is, P-AC and C-AC, respectively. We focused on the stability of various kinds of electrode materials, such as AC, C-AC, P-AC, commercial graphite, and graphene, under fast-charging conditions. Among these methods, P-AC exhibited the most stable and highest capacity during 500 cycles at the 5C rate, although the initial capacity (<50 cycles) of P-AC was given the second priority. We believe that the suitable mixture of meso- and micropores in P-ACs increases the diffusivity and insertion rate of the Li-ion (solvation) at fast-charging condition, thereby leading to higher long-term stability.