Events

Topochemistry refers to a generic category of solid-state reactions in which precursors and products display strong filiation in their crystal structures. Various layered transition metal oxides and chalcogenides are subject to this stepwise structure transformation, by accommodating guest atoms or molecules in between their 2D slabs loosely bound by van der Waals (vdW) interactions. This “sandwich”-type host-guest chemistry is often coupled with redox reactions of transition metal cations embedded in the host frameworks, thereby finding utility not only in engineering of crystal structures but also in various applications such as Li-ion secondary batteries.
Over the recent years, we have been interested in materials design beyond the scope of such sandwich-type topochemistry that was mostly limited to vdW systems. For this, we recently proposed new topochemical reactions of non-vdW compounds built of 2D array of anionic chalcogen dimers alternating with redox-inert, host cationic layers. We found that these chalcogen dimers underwent redox reaction with external metal elements, triggering either (1) insertion of these metals to construct 2D metal chalcogenides, or (2) deintercalation of the constituent chalcogen anions. As a whole, this topochemistry works like a “zipper”, where reductive cleavage of anionic chalcogen-chalcogen bonds opens up spaces in non-vdW materials, allowing formation of novel layered structures.
The presentation will provide a brief overview of this new “zipper”-type topochemistry based on anionic redox, and then open a discussion about its future perspective and challenges.

Abstract:

Advancing All-Solid-State Batteries: Electrolyte Synthesis, Electrode Optimization, and Cathode Material Development