Ogihara Nobuhiro, Ohba Nobuko, Kishida Yoshihiro
Toyota Central R&D Laboratories Inc., Nagakute, Aichi 480-1192, Japan.
Sci Adv. 2017 Aug 25;3(8):e1603103. doi: 10.1126/sciadv.1603103. eCollection 2017 Aug.
The electrical properties of metal-organic frameworks (MOF) have attracted attention for MOF as electronic materials. We report on/off switchable electronic conduction behavior with thermal responsiveness in intercalated MOF (iMOF) with layered structure, 2,6-naphthalene dicarboxylate dilithium, which was previously reported as a reversible Li-intercalation electrode material. The - response of the intercalated sample, which was prepared using a chemically reductive lithiation agent, exhibits current flow with sufficiently high electronic conductivity, even though it displays insulating characteristics in the pristine state. Calculations of band structure and electron hopping conduction indicate that electronic conduction occurs in the two-dimensional π-stacking naphthalene layers when the band gap is decreased to 0.99 eV and because of the formation of an anisotropic electron hopping conduction pathway by Li intercalation. The structure exhibiting electronic conductivity remains stable up to 200°C and reverts to an insulating structure, without collapsing, at 400°C, offering the potential for a shutdown switch for battery safety during thermal runaway or for heat-responsive on/off switching electronic devices.
金属有机框架材料（MOF）的电学性质使其作为电子材料受到关注。我们报道了具有层状结构的插层MOF（iMOF）——2,6-萘二甲酸二锂，其具有热响应性的开/关可切换电子传导行为，该材料先前被报道为一种可逆的锂插层电极材料。使用化学还原锂化剂制备的插层样品的响应显示，即使其在原始状态下表现出绝缘特性，但仍具有足够高的电子电导率的电流流动。能带结构和电子跳跃传导的计算表明，当带隙减小到0.99 eV时，由于锂插层形成了各向异性的电子跳跃传导途径，二维π-堆积萘层中发生了电子传导。表现出电子导电性的结构在高达200°C时保持稳定，并在400°C时恢复为绝缘结构且不坍塌，这为热失控期间电池安全的关闭开关或热响应开/关切换电子设备提供了潜力。
