Grinding-exfoliated 2D transition metal dichalcogenides as scalable binders for freestanding, additive-free electrodes

Abstract

Polymeric binders are an essential component of electrode preparation; however, conventional binders can result in a loss of approximately 20 % to 40 % of the active electrode weight due to the addition of conductive additives and the polymer itself. 2D pseudocapacitive binders from the transition metal dichalcogenide (TMD) family (e.g., MoS₂, MoSe₂, WS₂, WSe₂) were introduced to address this. These materials also contribute to reduced NMP consumption during electrode fabrication. The sheet-like structure of exfoliated TMDs enables van der Waals interactions between adjacent layers, effectively binding active particles together while preserving the active surface area. Notably, the use of WSe₂ as one of the TMD binders doubled the capacitance compared to conventional polymeric binders, achieving a high capacitance of 61.25 F g⁻¹ at 0.10 A g⁻¹ and delivering a power density of 2200 W kg⁻¹ at an energy density of 78 Wh kg⁻¹ for a freestanding electrode. This improvement is attributed to the pseudocapacitive nature of TMDs, which enhances charge storage. Furthermore, the WSe₂ binder exhibited excellent cycling stability, retaining 115.73 % of its capacity at a high rate after 10,000 charge/discharge cycles, enabling faster charging. This work paves the way for utilizing other 2D materials as multifunctional binders for electrode preparation, driving the continued development of energy storage design.