Enhanced Li-ion diffusion improves N <sub>2</sub> -to-NH <sub>3</sub> current efficiency at 100 mA cm <sup>−2</sup>
Qiang Zhang, Huamin Li, Peiping Yu, Pengyu Liu, Ning Sun, Yuyi Wang, Chunlai Tu, Yiping Liu, Yan Wang, Xinyang Yue, Linlin Ma, Wen Wen, Jinyang Xu, Zhaofeng Liang, Jingyuan Ma, Fei Song, Zheng Liang, Hao Sun, Daishun Ling, Hongyan Liang, Feng Liu, Yongfeng Hu, Tao Cheng, Jun Li
Abstract
Electrochemical lithium (Li)–mediated nitrogen (N 2 ) reduction could enable production of ammonia (NH 3 ) at ambient temperatures and pressures, offering a route to reduce carbon emissions in the chemical sector. However, NH 3 productivity is often limited by sluggish Li-ion desolvation and diffusion at the solid electrolyte interphase (SEI). Here, we present a concerted desolvation:diffusion layered SEI architecture that provides abundant Li-ion flux for efficient N 2 conversion toward NH 3 production at high current densities. The SEI comprises stacked inorganic layers with low ion-binding affinity and high ion-conductivity functionalities that increase Li-ion flux by two orders of magnitude. This design strategy achieved N 2 electroreduction in a 2 M lithium difluoro(oxalato)borate electrolyte with a Faradaic efficiency of 98% and an energy efficiency of 21% for NH 3 production at 100 milliamperes per square centimeter (mA cm −2 ). The system sustained an 80% Faradaic efficiency over 40 hours, after which performance declined.