In the past 20 years, PVDF binders have been excluded for use with Si anodes due to their very poor electrochemical performance. To overcome this fundamental challenge, we propose a novel strategy of creating a functional buffer layer on the Si particle surface, i.e. a supramolecular layer of nickel ion-trimesic acid. The layer is able to protect Si particles and isolate Si from the PVDF chain. The applied supramolecular buffer layer not only coherently bonds with the Si core, but also promotes the formation of a stable SEI layer. As a result, an Si anode using a PVDF binder exhibits much improved initial coulombic efficiency, high rate capability and excellent cycling stability. After 200 electrochemical cycles, a reversible capacity of 1900.6 mA h g⁻¹, corresponding to a capacity retention of 92%, is obtained, which is in sharp contrast to the almost zero capacity for a reference Si anode. The successful use of a traditional PVDF binder with an extremely high capacity Si anode provides a new avenue for the development of Si anodes for high-energy-density lithium-ion batteries.

Silicon (Si) anodes are urgently required in the pursuit of high-energy-density batteries yet plagued by their large volumetric changes and the resultant fast capacity decay. The consensus is that polymeric binders are crucial to effectively secure the electrode integrity against repetitive lithiation/delithiation cycles. Herein, a molecular design of a multifunctional network is presented, created by grafting acrylamide (AAm) monomer onto poly(vinyl alcohol) (PVA) chains, followed by crosslinking to form a 3D network. In this design, the strong PVA backbone binds tightly to the Si surface with its hydroxyl groups, whereas the highly stretchable polyacrylamide (PAAm) branch endows the binder with adequate flexibility and improved Li⁺ conductivity. After proper optimization, the Si anode using the c-PVA-g-PAAm binder exhibits improved mechanics and surface chemistry. Thus, a high discharge capacity of 1590.5 mA h g⁻¹ has been achieved after 500 deep cycles at a current density of 4.2 A g⁻¹ (1C), corresponding to a capacity retention of 75.9%. At a high rate of 20C, the Si electrode is able to deliver a capacity of 2141.64 mA h g⁻¹.