Understanding Zn‐Ion Insertion Chemistry through Nonaqueous Electrochemical Investigation of 2H‐NbSe₂

Abstract Electrochemical Zn‐ion insertion into 2H‐NbSe₂, which can be considered as a platform host, is investigated with bulk and microflower particles formed of nanosheets to bolster the understanding of Zn‐ion insertion chemistry. While electrochemical Zn‐ion insertion into bulk particles of 2H‐NbSe₂ is observed to be hindered, it is found to be reversible and facile with microflower particles formed of nanosheets, emphasizing the importance of minimizing the kinetic limitations to Zn‐ion insertion. Also, the facile diffusion characteristics of Zn ions in the microflower particles of 2H‐NbSe₂ is determined to be due to both its morphology that provides shortened diffusion length and the relatively low Zn‐ion migration barrier of 0.59 eV in the 2H‐NbSe₂ structure, which is comparable to Li‐ion migration barrier in the well‐known spinel LiMn₂O₄. Such relatively low migration barrier of a multivalent ion like Zn²⁺ ion in 2H‐NbSe₂ highlights the criticality of achieving weaker host–guest interaction for a multivalent‐ion host material as well as the reduced particle size to attain appreciable diffusion and reversible electrochemical behavior.