Polymer binder selection greatly impacts electrode performance, production, and recyclability in batteries and energy storage systems. We introduce a novel family of polymer binders that provide several key advantages over traditional binders in Li-ion batteries. Our findings show that in-situ cross-linked networks of eco-friendly polyesters bearing pendant carboxylic moieties can serve as superior binders for electrodes. When tested specifically in high‑silicon-content anodes, the electrodes exhibit high initial coulombic efficiency and sustain impressive specific capacity retention after 300 cycles. They reach approximately 2500 mAh/g, compared to 1580 mAh/g for electrodes using conventional PAA binders. Furthermore, the anode shows stable cycling performance when paired with NMC532 cathodes in full Li-ion cell tests. Notably, the transition of silicon from intermediate phases to its fully lithiated state is more efficient with the polyester binder, attributed to the formation of a more stable solid-electrolyte interphase (SEI) layer and reduced impedance. We assign the high performance of our binder to the presence of the polar groups, e.g. carbonyl, in the primary polymer chain, along with the end functional moieties, promoting Li+ solvation and transport, resulting in a high ionic conductivity of the binder. Moreover, the inherent flexibility in the formulations of the polyesters enables fine-tuning of properties such as adhesion, elasticity, and a suitable glass transition temperature, all of which could be customized to optimize battery performance. Produced from renewable feedstocks and adopting water-based or solvent-free fabrication processes, these polyesters offer a fully sustainable solution from production to recycling at the end of the battery's life.