'Breathing-crystals' the origin of electrochemical activity of mesoporous Li-MnO sub(2)

Akin to Le Chatalier's principle, we show that a mesoporous material can mitigate the effect of stress by expanding or contracting elastically into the pore space; we simulate this 'breathing-crystal' phenomenon using MD simulation. In particular, our simulations reveal that mesoporous Li-MnO sub(2) is electrochemically active because the stress, associated with charge cycling, does not influence the structure or dimensions of the (unlithiated) 1 1 tunnels in which the lithium ions intercalate and reside. Conversely, the parent bulk material suffers structural collapse and blockage of the 1 1 tunnels under stress. The mechanism associated with Li deintercalation is presented together with the activation energy barriers, which are calculated to be 0.4 eV - irrespective of whether the mesoporous host is unstrained or under considerable (1.6 GPa) tensile or compressive stress.