An organic and inorganic composite binder with excellent mechanical property and good ionic conductivity for high performance Si anode of lithium-ion batteries

The theoretical capacity of silicon (Si) is high, which makes it a highly promising anode material for the development of next-generation lithium-ion batteries (LIBs). However, its severe volume variation (>300%) during lithiation/de-lithiation leads to rapid electrochemical failure, impeding its practical deployment. Addressing this challenge, the optimization of binders emerges as a pivotal strategy. Herein, we developed a composite binder, denoted as CCL, by chemically crosslinking carboxymethyl cellulose (CMC) with lithium silicate (LS) using citric acid (CA). This molecular design integrates the rigidity of LS with the flexibility of CMC, yielding a binder with superior mechanical robustness to accommodate the cyclic strain of Si particles. Furthermore, the CCL binder exhibits strong adhesion to the Si surface through interactions between the Si O groups in CCL and the silanol (Si-OH) groups on Si. This coupled with the excellent film-forming ability of CMC, ensures electrode integrity. Concurrently, oxygen ions derived from LS enhance lithium-ion transport, thereby improving rate capability. The CCL binder also contributes to a more stable solid electrolyte interphase (SEI) by mitigating parasitic reactions. As a result, the Si/CCL anode delivered exceptional long-term cycling stability, retaining a high reversible capacity of 1192 mAh g −1 after 500 cycles at 2.0 A g −1 . The superior mechanical and ionic transport properties of CCL also proved advantageous in all-solid-state LIBs, where the anode demonstrated a discharge capacity of 1617.4 mAh g −1 at 1.0 A g −1 after 100 cycles at 25 °C. These findings underscore the significant potential of the CCL binder for practical Si anodes and offer a valuable design strategy for future binder systems.