International Center for Materials Nanoarchitectonics (WPI-MANA), National Institute for Materials Science (NIMS) , Namiki 1-1, Tsukuba, Ibaraki 305-0044, Japan.
ACS Nano. 2018 Feb 27;12(2):1768-1777. doi: 10.1021/acsnano.7b08522. Epub 2018 Jan 22.
Two-dimensional (2D) metal oxide nanosheets can exhibit exceptional electrochemical performance owing to their shortened ion diffusion distances, abundant active sites, and various valence states. Especially, genuine unilamellar nanosheets with an atomic-scale thickness are expected to exhibit the ultimate energy storage capability but have not yet achieved their potential. Here, we demonstrate the utilization of genuine unilamellar MnO nanosheets for high-performance Li and Na storage using an alternately stacked MnO/graphene superlattice-like structure. Different from previous reports, all unilamellar MnO nanosheets are separated and stabilized between the graphene monolayers, resulting in highly reversible 2D-confined conversion processes. As a consequence, large specific capacities of 1325 and 795 mA h g at 0.1 A g, high-rate capacities of 370 and 245 mA h g at 12.8 A g, and excellent cycling stabilities after 5000 cycles with ∼0.004% and 0.0078% capacity decay per cycle were obtained for Li and Na storage, respectively, presenting the best reported performance to date.
二维（2D）金属氧化物纳米片由于其缩短的离子扩散距离、丰富的活性位点和各种价态，表现出优异的电化学性能。特别是具有原子级厚度的真正单层纳米片有望展现出最终的储能能力，但尚未发挥其潜力。在这里，我们展示了利用真正的单层 MnO 纳米片，通过交替堆叠的 MnO/石墨烯超晶格结构，实现高性能的 Li 和 Na 存储。与以前的报告不同，所有的单层 MnO 纳米片都在石墨烯单层之间分离和稳定，从而实现了高度可逆的 2D 限制的转化过程。因此，对于 Li 和 Na 存储，分别获得了 1325 和 795 mA h g 在 0.1 A g 时的大比容量、370 和 245 mA h g 在 12.8 A g 时的高倍率容量，以及在 5000 次循环后分别约为 0.004%和 0.0078%的容量衰减率的优异循环稳定性，这是迄今为止报道的最佳性能。
