Polymer Blends of Pectin/Poly(acrylic acid) as Efficient Binders for Silicon Anodes in Lithium‐Ion Batteries

Abstract Polymeric binders have frequently been applied as an important component of Si‐based anodes in lithium‐ion batteries, because they can efficiently restrict the large volume change of Si nanoparticles (Si NPs) during charging/discharging cycles. Therefore, we developed a novel pectin/poly(acrylic acid) (PECAA/PAA) blend binder with reversible elasticity to sustain the volume change of Si NPs. Through the study on pure PAA and PEC/PAA( x ) ( x : weight fraction of PEC), a subtle balance between mechanical properties and density of interacting groups was found to be important in controlling the binding and electrochemical performances of the Si anodes. The PAA‐based Si anode is inferior in terms of the performance, but the addition of PEC resulted in the PEC/PAA(10) anode with an excellent binding and electrochemical performance. The PEC/PAA(10) anode exhibited a high capacity of 2386 mAh g −1 after 100 cycles, significantly higher than 1508 mAh g −1 from the PAA anode. However, a further increase of PEC content adversely reduced the electrochemical performance of the PEC/PAA(20) and (30) anodes, owing to the decrease in the interacting COOH groups. Optimal composition adjustment is, therefore, of crucial importance in achieving a polymer blend binder with enhanced binding and electrochemical performances.