'Breathing-crystals' the origin of electrochemical activity of mesoporous Li–MnO2. Issue 17 (12th April 2016)

• Record Type: Journal Article
• Authors: Sayle, Thi X. T.; Kgatwane, Kenneth; Ngoepe, Phuti E.; Sayle, Dean C.
• Is Part Of: Journal of materials chemistry. Volume 4:Issue 17(2016)
• Page Start: 6456
• Page End: 6464
• Publication Date: 2016-04-12
• Subjects: Materials -- Research -- Periodicals; Chemistry, Analytic -- Periodicals; Environmental sciences -- Research -- Periodicals; 543.0284
• DOI: 10.1039/c6ta01832g
• Languages: English
• ISSNs: 2050-7488

Abstract

Abstract : 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. Abstract : 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–MnO2 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.