Intercalation and delamination of Ti₂SnC with high lithium ion storage capacity

Li-ion batteries attract great attention due to the rapidly increasing and urgent demand for high energy storage devices. MAX phase compounds, layered ternary transition metal carbides and/or nitrides show promise as candidate materials of electrodes for Li-ion batteries. However, the highest specific capacity reported up to now is relatively low (180 mA h g^-1), preventing them from use in real applications. Exploring more MAX phase compounds with delaminated two-dimensional structure is an effective solution to increase the specific capacity. Herein, we report the reversible electrochemical intercalation of Li⁺ into Ti₂SnC (MAX phase) nanosheets. Owing to the synergistic effects of intercalation and dimethyl sulfoxide (DMSO)-assisted exfoliation, Ti₂SnC nanosheets are successfully obtained via sonication in DMSO. Moreover, when using as an anode of a Li-ion battery, Ti₂SnC nanosheets exhibited an increasing specific capacity with cycling due to the exfoliation of Ti₂SnC nanosheets via reversible Li-ion intercalation. After 1000 charge-discharge cycles, Ti₂SnC nanosheets delivered a high specific capacity of 735 mA h g^-1 at a current density of 50 mA g^-1, which is far better than other MAX phases, such as Ti₂SC, Ti₃SiC₂ and Nb₂SnC. The current work demonstrates the Li-ion storage potential and indicates a novel strategy for further intercalation and delamination of MAX phases.