SiO2-Enhanced Structural Stability and Strong Adhesion with a New Binder of Konjac Glucomannan Enables Stable Cycling of Silicon Anodes for Lithium-Ion Batteries

Silicon-based anodes with high theoretical capacity have intriguing potential applications for next-generation high-energy lithium-ion batteries, but suffer from huge volumetric change that causes pulverization of electrodes. Rational design and construction of effective electrode structures combined with versatile binders remain a significant challenge. Here, a unique natural binder of konjac glucomannan (KGM) is developed and an amorphous protective layer of SiO2 is fabricated on the surface of Si nanoparticles (Si@SiO2) to enhance the adhesion. Benefiting from a plethora of hydroxyl groups, the KGM binder with inherently high adhesion and superior mechanical properties provides abundant contact sites to active materials. Molecular mechanics simulations and experimental results demonstrate that the enhanced adhesion between KGM and Si@SiO2 can bond the particles tightly to form a robust electrode. In addition to bridging KGM molecules, the SiO2-functionalized surface may serve as a buffer layer to alleviate the stresses of Si nanoparticles resulting from the volume change. The as-fabricated KGM/Si@SiO2 electrode exhibits outstanding structural stability upon long-term cycles. A highly reversible capacity of 1278 mAh g(-1) can be achieved over 1000 cycles at a current density of 2 A g(-1), and the capacity decay is as small as 0.056% per cycle.