'Breathing-crystals' the origin of electrochemical activity of mesoporous Li-MnO 2
'Breathing-crystals' the origin of electrochemical activity of mesoporous Li-MnO 2
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“呼吸晶体”介孔Li-MnO 2 电化学活性的起源
DOI：
10.1039/c6ta01832g
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发表时间：
2016
影响因子：
11.9
通讯作者：
Sayle T
中科院分区：
文献类型：
--
作者：
Sayle T
与Le Chatalier原理类似，我们证明了介孔材料可以通过弹性地扩展或收缩到孔隙空间来缓解应力的影响；我们使用MD模拟来模拟这种“呼吸-结晶”现象。特别是，我们的模拟表明介孔Li-MnO2具有电化学活性，因为与电荷循环有关的应力不影响锂离子嵌入和驻留的(未加锂的)1×1隧道的结构和尺寸。相反，母体材料在应力作用下会导致1×1隧道的结构坍塌和堵塞。与Li脱嵌相关的机理和活化能势垒被计算为0.4 eV--无论介孔主体是无应变的还是承受相当大的(1.6 Gpa)拉应力或压应力。
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.