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

## TL;DR

A new cathode design improves the longevity of silicon monoxide/graphite anodes in lithium-ion batteries without reducing energy density.

## Contribution

A bimodal cathode design using single- and polycrystalline NCM particles is introduced to control SiO anode discharge depth and enhance cycle stability.

## Key findings

- Bimodal cathode particles induce overpotential rise at end-of-discharge, lowering anode endpoint potential.
- The design suppresses SiO mechanical degradation and enables stable long-term cycling.
- Operando XRD confirms the effectiveness of the strategy in maintaining energy density.

## 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.

A bimodal cathode composed of single‐ and polycrystalline NCM particles induces end‐of‐discharge overpotential rise via reaction heterogeneity, effectively regulating the depth of discharge of SiO in SiO/graphite anodes. This design suppresses mechanical degradation of SiO and enables long‐term cycling stability without compromising the energy density of full cells.