Nitrogen-Centered Organic Salts Enable Stable Lithium-Ion Supply for High-Energy-Density Batteries
Ziyang Kang, Shengfei Wang, Gang Wu, Shu Chen, Zilong Zheng, Wenwen Wang, Xinwei Du, Huajing Li, Mengyao Zhu, Huisheng Peng, Yue Gao
Abstract
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.