Enabling Fast Charging of Lithium-Ion Batteries With Regioisomeric Nitrile Additives for Interphase Regulation

Achieving fast charging across a wide range of operating conditions remains challenging for lithium (Li)-ion batteries due to unstable electrode-electrolyte interphases (EEIs) and sluggish interfacial kinetics. Here, we introduce a nitrile-based additive strategy to regulate interphase formation, while maintaining full compatibility with the commercial LP57 electrolyte, thereby avoiding the need for expensive salts or complex electrolyte reformulation. By incorporating only 0.5 wt.% of 3-(trifluoromethyl) benzonitrile (AD3), the modified electrolyte significantly enhances fast-charging performance in 1 Ah Graphite (Gr) | LiNi_0.8Mn_0.1Co_0.1O₂ pouch cells, while also improving low-temperature, high-temperature, and high-voltage stabilities. Mechanistic analysis reveals that AD3 fundamentally alters the interphase formation at both electrodes. At the cathode, AD3 suppresses penetration of decomposition products and enables the formation of a thinner, more uniform cathode-electrolyte interphase. At the anode, its preferential reduction leads to a thin (10 nm), well-controlled solid-electrolyte interphase (SEI) and effectively suppresses Li plating, in contrast to a thick (450 nm), Li-rich layer formed in LP57. The interfacial improvements reduce parasitic reactions and lower interfacial resistance, as confirmed by distribution of relaxation times (DRT) analysis. The work demonstrates that minimal additive engineering can simultaneously stabilize interphases and enable fast charging, offering a cost-effective, industry-compatible pathway for next-generation Li-ion batteries.