Low-potential Li2C2O4 prelithiation catalyzed by 2D MoN with dominant (002) crystal face for high-energy lithium-ion batteries

Abstract

Lithium oxalate (Li₂C₂O₄) is considered as an ideal prelithiation agent owing to its high specific capacity and cost-effectiveness. However, the high reaction energy barrier and low intrinsic conductivity lead to a lithium liberation potential higher than 4.5 V, which severely trials the tolerance of the electrolyte and electrodes and significantly compromises the battery performance. In this study, two-dimensional molybdenum nitride (MoN) with (002) dominant exposed crystal face having superior catalytic properties is engineered to promote the low-potential decomposition of Li₂C₂O₄. With its half-filled electronic state of surface Mo atoms and ultra-high electronic conductivity, highly polarized MoN can effectively adsorb and catalyze the decomposition of Li₂C₂O₄, thus reducing the lithium liberation reaction energy barrier by 46.8 %. As a result, the lithium liberation potential of Li₂C₂O₄ is diminished to 3.9 V. When paired with LiFePO₄ (LFP) and LiNi_0.5Co_0.3Mn_0.2O₂ (NCM) cathode, forming Graphite || LFP-L and SiO_x || NCM-L full cells, the capacity increase by 5.5 % and 11 %, respectively. Additionally, prelithiation facilitates the formation of a fluorine-rich solid electrolyte interphase (SEI) on the anode, markedly improving the cycling stability of the battery.