Dual crosslinked binders based on poly(2-hydroxyethyl methacrylate) and polyacrylic acid for silicon anode in lithium-ion battery

The high specific capacity of silicon (Si) has earned increasing research interest in the Si-based anode material for lithium ion batteries (LIB). However, the serious volume change of Si during lithiation/delithiation process has been a major problem in the fabrication of effective Si anodes. To effectively restrict the volume change, a novel dual crosslinked binder, synthesized from crosslinking esterification reaction of poly(hydroxyethyl methacrylate) (PHM) and polyacrylic acid (PAA), was designed and used to fabricate Si anode for characterization. Besides the chemical crosslinked structure, the dual crosslinked cxPHM/PAA(x)s (x: weight percentage of PHM) own the reversible hydrogen bond (H bond) interactions, which could effectively hold the Si nanoparticles (Si NPs) during volume change. Comparison between the crosslinked cxPHM/PAA(x) anodes and the anodes based on the PHM/PAA(x) precursor blends revealed the beneficial role of chemical crosslinked network on the electrochemical performances of the Si anodes. Among all anodes, cxPHM/PAA(30) exhibited an adequate balance between H bonds and crosslinked covalent bonds, and was integrated into an anode with the best capacity retention of 2601 mAh g−1 at 0.2 C after 100 cycles.