Leveraging Reaction Heterogeneity in Bimodal Cathodes to Enhance Longevity of SiO/Graphite | NCM Full cells

Abstract

High-energy-density lithium-ion batteries are crucial for accelerating the widespread adoption of electric vehicles. Silicon monoxide/graphite (SiO/Gr) composite anodes have attracted considerable attention as promising candidates for increasing energy density. However, severe capacity degradation caused by the large volume changes of SiO during charge-discharge cycles remains a major obstacle to commercialization. One effective strategy to address this issue is to limit the charge/discharge operating voltage range (swing range) of the SiO anode. In this study, a cathode design composed of single-crystalline and polycrystalline LiNi0.8Co0.1Mn0.1O2(NCM811) with a bimodal particle size distribution is proposed to effectively control the charge-discharge operating range of the SiO anode within a full-cell. This design leverages the reaction heterogeneity of the cathode particles to induce an increase in overpotential at the end of discharge, effectively lowering the discharge endpoint potential of the anode. This design strategy enables stable cycling performance without compromising full-cell energy density by selectively controlling the discharge depth of SiO in the SiO/Gr anode. The effectiveness of this design is validated through various electrochemical analyses and real-time operando X-ray Diffraction (XRD), demonstrating that it is an efficient strategy to enhance the long-term cycle stability of SiO/Gr anodes without sacrificing energy density.