Using carbon black to facilitate fast charging in lithium-ion batteries

High-energy-density lithium (Li)-ion batteries with excellent fast-charging ability are crucial for popularizing electric vehicles (EVs). Although graphite has a high energy density, the near 0 V redox potential vs. Li/Li⁺ and selective Li⁺ intercalation limit its application for fast charging. Carbon black (CB) is an amorphous carbon with graphite-like crystallites that have more orientations and a larger lattice spacing than graphite, thereby facilitating Li⁺ intercalation. CB is only recently investigated for fast-charging applications. Here, the battery performance is systematically improved by modifying the CB content of graphite, thereby endowing batteries with a high energy density and a fast-charging ability. Optimized anodes with a commercial-level areal capacity of approximately 3 mAh cm^-2 are prepared and used to prepare pouch cells (>2 A h). These cells have a high energy density of 200 Wh kg^-1 and 420 Wh L^-1 and retain 87% of the initial capacity after 500 cycles at 3C. The improved fast-charging ability is attributed to the reduction in the Li⁺ intercalation resistance after the introduction of CB. The composite anode fabrication is compatible with the existing production processes. Thus, the composite anode can potentially be used with high-capacity cathodes to fabricate high-energy-density batteries with fast-charging ability for EVs.