Double-emulsion synthesis of reactive epoxy nanospheres for advanced lithium-ion battery binders

Abstract

The rapid advancement of electric vehicles imposes significant challenges on lithium-ion battery (LIBs) technology. Polymer binders offer a promising low-cost solution. However, for anode materials, the conventional styrene butadiene latex/carboxymethyl cellulose (SBR/CMC) binders exhibit inherent issues, including binder flotation during solvent evaporation and undesired film formation on anode surfaces. Herein, ultra-small reactive epoxy nanospheres (EPS, 70 nm) were successfully synthesized using a customized double emulsion (DE) demulsification method. The structural design of the internal water phase, two consecutive emulsifications and an innovative phase inversion strategy are crucial to achieve ultra-small particle size. By eliminating the binder migration phenomenon and establishing a covalent cross-linked network within the electrode, the EPS bonded electrode achieved a peel strength of 7.03 N cm⁻¹, surpassing the 4.53 N cm⁻¹ observed in the SBR bonded electrode. Furthermore, EPS can optimize the electrode pore structure and increase the electrode’s wettability to the electrolyte, thereby improving the electrode rate performance. At a current density of 10C, the EPS bonded electrode achieved a capacity retention of 50.4 %, which is much higher than that of the SBR bonded electrode (21.2 %). Consequently, reactive EPS presents an effective way to enhance the overall performance of LIBs through the strategic design of polymer binders.