Disordered Carbon Anode for Lithium-Ion Battery: I. An Interfacial Reversible Redox Action and Anomalous Topology Changes

Abstract

The authors investigated mechanisms for an interfacial reversible surface redox action and a solid electrolyte interphase (SEI) formation based on LiF with surface topology changes for a disordered carbon electrode in . The electrochemical reaction mechanism that delivers a large capacity was found to occur differently in two potential regions, region A (1.4 to 0.4 V) and B (0.4 to 0.0 V). During the reversible process in region A, a lithium alkoxide (C-OLi) is formed on the carbonyl edge planes as solvated lithium complex of the (, 2, or 3). The formation of the lithium alkoxide traps solvents on the edge surfaces preventing further intrusion into stacked graphene sheets, that in turn suppresses a exfoliation and stabilized repeated redox cycles. In region A, a and a LiF are formed as an SEI film by the reduction of solvents and making a smooth surface. region B involves three parallel processes, viz., a lithium intercalation into graphene layers, a lithium metal cluster deposition at nanosized voids or pores, and a formation of LiF by disproportionation of the C-OLi formed at region A. Since the LiF is produced rapidly by a proposed repeated cycle, the electrode surface generates a rough anomalous topology.