Degradation Mechanism Induced by Depth‐Dependent Inhomogeneity in Thick High‐Areal‐Capacity Graphite Electrode

Employing thick electrodes with high active material loading is one of the most practical approaches to enhance the energy density of lithium-ion batteries by fully leverage the potential of electrode materials. However, use of thick electrodes typically leads to a significant decline in electrode performance, accompanied by accelerated electrode degradation. Herein, the degradation mechanism is elucidated in high-loading graphite electrodes, driven by depth-dependent reaction inhomogeneity along the electrode thickness. It is demonstrated that the inhomogeneity is primarily caused by entrapment of lithium ions at the bottom of the electrode, progressively worsening with cycles, and contributes to the generation of current hotspots particularly at the top of the electrode. These hotspots trigger excessive solid electrolyte interphase formation, causing a sharp rise in charge transfer res…