Two-dimensional (2D) materials offer numerous advantages for electrochemical energy storage and conversion due to fast charge transfer kinetics, highly accessible surface area, and tunable electronic and optical properties. Stacking of 2D materials generates heterogeneous interfaces that can modify native chemical and physical material properties. Here, we demonstrate that local strain at a carbon-MoS₂ interface in a vertically stacked 2D material directs the pathway for chemical storage in MoS₂ on lithium metal insertion. With average measured MoS₂ strain of ~0.1% due to lattice mismatch between the carbon and MoS₂ layers, lithium insertion is facilitated by an energy-efficient cation-exchange transformation. This is compared with low-voltage lithium intercalation for unstrained MoS₂. This observation implies that mechanical properties of interfaces in heterogeneous 2D materials can be leveraged to direct energetics of chemical processes relevant to a wide range of applications such as electrochemical energy storage and conversion, catalysis and sensing.

Nature Communications 7, Article number: 11796 doi:10.1038/ncomms11796
Received 28 December 2015 Accepted 28 April 2016 Published 03 June 2016

http://www.nature.com/ncomms/2016/160603/ncomms11796/full/ncomms11796.html