Faster and better: A polymeric chaperone binder for microenvironment management in thick battery electrodes

Achieving high-performance thick battery electrodes via cost-efficient way is crucial for next-generation lithium/sodium ion batteries. However, the challenge comes from both a poor understanding of electrode microstructures and the lack of industry-friendly strategies on regulating the microstructures during the electrode fabrication. Here, as inspired by the chaperone in biology, a polymeric chaperone binder is reported to efficiently regulate the electrode microstructures. Firstly, the polymeric chaperone binder is realized by alloying poly(vinylidene fluoride) (PVDF) with ultra-high molecular weight poly(ethylene oxide), which generates unprecedented binder performance as compared with PVDF binder. Consequently, high-quality thick electrodes with a high active material (AM) loading around 60 mg/cm2 (about 2 times of the commercial level) are fabricated with over 80% reduction of energy consumption in slurry drying process. Meanwhile, the microstructures and properties of AM microenvironment are further characterized by micro-probe scanning, electro-rheology and bending testing, for the first time. Finally, thick electrodes with a high areal capacity of 8 mAh/cm2 @0.1C, superior C-rate and cycling performance have been demonstrated. In short, this study not only proposes an industry-friendly binder design strategy, but also uncovers the critical roles of binder solution in controlling the AM microenvironment quality and so the overall electrochemical performance.