Enhancing Fast‐Charging Capability of Thick Electrode in Lithium‐Ion Batteries Through Electronic/Ionic Hybrid Conductive Additive Engineering

Abstract The attainment of lithium‐ion batteries (LIBs) featuring high energy density necessitates the anode to exhibit substantial mass loading and thickness. However, this presents a formidable challenge for fast charging due to inferior Li‐ion transport capability throughout the electrode depth, resulting in diminished capacity, reduced lifespan, and potential safety hazards. Here, an alternative strategy is put forth that utilizes an electronic/ionic hybrid conductive additive as a substitution for the conventional conductive reagent. This particular additive showcases carbon black (CB) particles adorned with ultrathin red phosphorus nanolayer (≈2 nm) (CB‐P), which undergo in situ transformation into stable ultrathin lithium phosphide (Li 3 P) nanolayer‐coated CB particles during the operation of the battery. Benefiting from the significant contribution of Li + conductive enhancement, the introduction of Li 3 P enables significantly increased apparent Li + transference number and similar ionic conductivity compared to CB additive (0.67 vs 0.42, 5.2 vs 4.1 mS cm −1 ). Notably, the pouch cell with graphite anode and CB‐P additive demonstrates a high capacity filling ratio of 83.5% within 15 min (4C, relative to that at 0.5C) under a high anode loading of 14.4 mg cm −2 (4.4 mAh cm −2 at 0.5C). The full pouch cell with SiO x anode and CB‐P additive exhibits an 82.1% capacity refilling at 4C charging rate (15 min, relative to that of 0.2C). In consideration of the superior compatibility with current electrode processing, the CB‐P additive can serve as a direct replacement for traditional CB additives in existing batteries and boost the implementation of fast‐charging LIBs with high energy density.