Lowering interfacial chemical reactivity of oxide materials for lithium batteries. A molecular grafting approach

Abstract

This paper proposes a molecular grafting approach as a way to modify the interfacial chemical reactivity of oxide materials, which is detrimental to their long-term energy storage properties. The present study demonstrates that diazonium chemistry offers an efficient path to graft molecules at the surface of a powder oxide material. Indeed, surface derivatization of Li_1.1V₃O₈ nanograins was accomplished by in situ electrografting of a diazonium salt during Li-ion intercalation. The results show that aryl molecules are strongly bonded to the surface forming an organic multilayer the thickness of which can be modulated. Based on TEM, XPS and electrochemical probing of the surface reactivity, the results demonstrate the interest of the proposed surface modifications as a way to tailor both electrochemical and chemical reactivities of oxide electrode materials. Interestingly, charge transfer at the surface of the material is not impeded, while electrolyte decomposition is inhibited. It is anticipated that molecular derivatization of electrode surfaces is a new research direction which will be developed in the field of battery science in the near future, in order to prevent targeted side reactions occurring at different steps of battery manufacturing and use, such as storage, electrode processing, simple contact with electrolyte, and cycling.