Nitrogen-Centered Organic Salts Enable Stable Lithium-Ion Supply for High-Energy-Density Batteries

Compensating lithium (Li) ions for high-energy-density batteries is essential, as the anodes such as silicon-based materials present up to 20% Li-ion loss in the initial cycle. Current Li-ion supply molecules present side reactions with battery components and lead to undesirable gas generation due to the intrinsic electrochemical mechanism. To address this, we report the design of a nitrogen (N)-centered organic salt, lithium-benzimidazol-2-one (Li 2 N 2 C 7 H 4 O), capable of supplying Li-ions without damaging the battery chemical environment and effectively protecting the Ni-rich cathode surface. This molecule, discovered through semisupervised machine learning, undergoes a two-step anodic reaction through a free radical pathway, releasing Li-ions and forming an electrolyte additive, benzimidazolone (C 7 H 4 N 2 O), to suppressing transition metal dissolution of the LiNi 0.8 Co 0.1 Mn 0.1 O 2 (NCM811) cathode. No gases were generated in this process. The complete conversion of Li 2 N 2 C 7 H 4 O and effective protection of NCM811 were confirmed by spectroscopic and microscopic characterizations. The utilization of Li 2 N 2 C 7 H 4 O effectively increased the capacity of a silicon monoxide (SiO)/C|NCM811 pouch cell from 186.7 to 205.5 mAh g –1, and the cell delivered an 84.1% capacity retention after 500 cycles, opening up an avenue to design a N-centered oxidation reaction mechanism for Li-ion supply in high-energy-density batteries.