Metal-organic framework glass anode with an exceptional cycling-induced capacity enhancement for lithium-ion batteries

Abstract Metal organic frameworks (MOFs) hold great promise as high-energy anode materials for next-generation lithium-ion batteries (LIBs) due to their tunable chemistry, pore structure and abundant reaction sites. However, the pore structure of crystalline MOFs tends to collapse during lithium-ion insertion and extraction, and hence, their electrochemical performances are rather limited. As a critical breakthrough, a MOF glass anode for LIBs has been developed in the present work. In detail, it was fabricated by melt-quenching Cobalt-ZIF-62 (Co(Im)_1.75(bIm)_0.25) to glass, and then by combining glass with carbon black and binder. The derived anode exhibits high lithium storage capacity (306 mAh g^-1 after 1000 cycles at of 2 A g^-1), outstanding cycling stability and superior rate performance compared with the crystalline Cobalt-ZIF-62 and the amorphous one prepared by high-energy ball-milling. Importantly, it was found that the Li-ion storage capacity of the MOF glass anode continuously rises with charge-discharge cycling and even tripled after 1000 cycles. Combined spectroscopic and structural analyses, along with density functional theory calculations, revealed the origin of the unusual cycling-enhancement of the performances of the MOF glass anode, that is, increased distortion and local breakage of the Co-N coordination making the Li-ion intercalation sites more accessible. This article is protected by copyright. All rights reserved