Lithium Borate/Boric Acid Optimized Multifunctional Binder Facilitates Silicon Anodes With Enhanced Initial Coulombic Efficiency, Structural Strength, and Cycling Stability

Silicon-based anodes are among the most appealing possibilities for high-capacity anode materials, considering that they possess a high theoretical capacity. However, the significant volumetric changes during cycling lead to rapid capacity degradation, hindering their commercial application in high-energy density lithium-ion batteries (LIBs). This research introduces a novel organic-inorganic cross-linked binder system: sodium alginate-lithium borate-boric acid (Alg-LBO-BA). This three-dimensional network structure effectively buffers the volumetric changes of Si particles, maintaining overall electrode stability. LBO serves as prelithiation agent, compensating for irreversible lithium consumption during SEI formation, and the Si−O−B structure offers a plethora of Lewis acid sites, enhancing lithium-ion transport and interfacial stability. At a current activation of 0.2 A g⁻¹, the optimized silicon anode shows an initial coulombic efficiency (ICE) of 91%. After 200 cycles at 1 A g⁻¹, it retains a reversible capacity of 1631.8 mAh g⁻¹ and achieves 1768.0 mAh g⁻¹ at a high current density of 5 A g⁻¹. This study presents a novel approach to designing organic-inorganic binders for silicon anodes, significantly advancing the development of high-performance silicon anodes.