Coupling Stress Delocalization With Lithiation Homogenization: Omnidirectional Conformal Interface Integrating Silicon Oxycarbide-Graphite Anode.

Integrating Si-based anodes with graphite has been widely recognized as an effective strategy for pursuing high-energy-density lithium-ion batteries (LIBs). However, the "stress singularity" effect arising from heterogeneous interfaces gradually leads to interfacial slippage and further triggers electrical isolation, fundamentally resulting in mechanical failure and kinetic heterogeneity within the electrode. Herein, we realize conformal interlocking between silicon oxycarbide (SiOC) and discrete graphite domains in developed omnidirectional conformal interface SiOC-graphite (OSiOCG) electrodes to overcome the "stress singularity" effect. Mechanically, the omnidirectional conformal interface effectively transforms localized piercing force into hydrostatically distributed compressive force, effectively dissipating the "stress singularity" effect. Kinetically, it crosslinks isolated sites of transfer of electron/Li-ion into 3D-percolation networks across the entire interface. This mitigates local polarization, regulates the sequence and depth of lithiation for active components, and further dissipates the concentrated stress. The OSiOCG electrodes deliver stabilized cycling for 2000 cycles (average capacity decay < 0.005% per cycle), optimized rate capability (capacity increases of 19.3% at 4C and 12.8% at 10C), and effective practicality validated in pouch cells (88.3% capacity retention at 4C). This work sheds light on interfacial stress delocalization within Si-based graphite composite electrodes while paving the way for long-term reliability enhancement of commercialized high-energy-density LIBs.