CNT boosted two-dimensional flaky metal-organic nanosheets for superior lithium and potassium storage

Abstract

Flaky nanosheets with superior molecular structures and functions are indispensable for high-performance lithium-ion batteries (LIBs) and potassium-ion batteries (PIBs). Herein, through a simple dispersion method, two-dimensional Co-MOF-CNT nanosheets are prepared by adding nanotubes (CNT) during the synthesis of MOF under microwave-assisted radiation conditions. The flaky dispersed sheet structure possesses more exposed surfaces and porous structures for Co-MOF-CNT, which is beneficial to offering numerous active sites and promoting the rapid transmission of Li/K-ions. Therefore, when applied as negative electrode for LIB and PIB, the Co-MOF-CNT nanosheets can provide an extremely enhanced reversible capacity (1451/286 mAh g−1 for LIBs/PIBs after 100 cycles at 100 mA g−1). In view of ex-situ XPS result, in-situ FTIR result and electrochemical detection, the excellent electrochemical performance is determined due to the activated lithium-reaction involving metal centers, CO groups and CC groups from benzene rings. The research on lithium/potassium reaction functional groups of MOF nanosheets with more activated energy-storage sites would further provide guidance for the exploration on superior-performance electrodes for future alkali metal secondary batteries.