Interlayer Expansion of Bulk MoS$_2$ via Top-Down Organic Pillaring Enables Tunable Li$^+$ Intercalation and Controlled Solvent Co-Intercalation

Interlayer engineering is widely used to improve charge storage in layered transition metal dichalcogenides, yet most studies rely on nanosized materials where the effects of interlayer expansion and particle downsizing are intertwined. Here, molecular pillaring is translated to bulk molybdenum disulfide (MoS$_2$) using a top-down strategy. Chemical pre-reduction with butyllithium enables exfoliation and restacking in the presence of hexanediammonium (HDA) molecules, forming a pillared MoS$_2$-HDA structure with an expanded interlayer spacing of 0.98 nm while preserving the bulk particle morphology and specific surface area. Electrochemical analysis reveals that improved rate capability primarily originates from the chemical activation associated with the pre-reduction step rather than from interlayer expansion itself. Operando X-ray diffraction and electrochemical dilatometry show that bulk MoS$_2$ undergoes solvent co-intercalation in diglyme electrolyte, leading to pronounced lattice expansion and electrode swelling. In contrast, pillared MoS$_2$-HDA suppresses solvent co-intercalation despite its larger interlayer spacing, demonstrating that interlayer expansion alone does not dictate solvent co-intercalation in layered electrodes.