Catalytic role of in-situ formed C-N species for enhanced Li2CO3 decomposition
Fangli Zhang, Wenchao Zhang, Jodie A. Yuwono, David Wexler, Yameng Fan, Jinshuo Zou, Gemeng Liang, Liang Sun, Zaiping Guo
Abstract
Abstract Sluggish kinetics of the CO 2 reduction/evolution reactions lead to the accumulation of Li 2 CO 3 residuals and thus possible catalyst deactivation, which hinders the long-term cycling stability of Li-CO 2 batteries. Apart from catalyst design, constructing a fluorinated solid-electrolyte interphase is a conventional strategy to minimize parasitic reactions and prolong cycle life. However, the catalytic effects of solid-electrolyte interphase components have been overlooked and remain unclear. Herein, we systematically regulate the compositions of solid-electrolyte interphase via tuning electrolyte solvation structures, anion coordination, and binding free energy between Li ion and anion. The cells exhibit distinct improvement in cycling performance with increasing content of C-N species in solid-electrolyte interphase layers. The enhancement originates from a catalytic effect towards accelerating the Li 2 CO 3 formation/decomposition kinetics. Theoretical analysis reveals that C-N species provide strong adsorption sites and promote charge transfer from interface to *CO 2 2− during discharge, and from Li 2 CO 3 to C-N species during charge, thereby building a bidirectional fast-reacting bridge for CO 2 reduction/evolution reactions. This finding enables us to design a C-N rich solid-electrolyte interphase via dual-salt electrolytes, improving cycle life of Li-CO 2 batteries to twice that using traditional electrolytes. Our work provides an insight into interfacial design by tuning of catalytic properties towards CO 2 reduction/evolution reactions.