State Key Laboratory of Chemical Resource Engineering, Beijing Key Laboratory of Electrochemical Process and Technology for Materials, Beijing University of Chemical Technology, Beijing, 100029, P. R. China.
Phys Chem Chem Phys. 2018 Jun 20;20(24):16437-16443. doi: 10.1039/c8cp01681j.
High-performance electrode materials that can be easily prepared are imperative for obtaining highly efficient lithium-ion batteries (LIBs). In this study, graphene-wrapped CoNi-layered double hydroxide (LDH) microspheres were first fabricated and used as an anode material for LIBs. The composite electrode with a mass ratio of 2.5 : 1 (CoNi-LDH/graphene) showed a high reversible specific capacity of 1428.0 mA h g-1 at 0.05 A g-1, excellent rate performances (977.5, 670.8 and 328.1 mA h g-1 at 0.5, 2 and 10 A g-1, respectively) and long-cycling performance (75% retention at 10 A g-1 after 10 000 cycles). The excellent electrochemical performances could be due to the following reasons: CoNi-LDHs had high chemical reactivity, and the graphene shell improved the electrical conductivity of CoNi-LDHs, which facilitated charge transfer; the graphene shell also suppressed the volume expansion of metal hydroxides during charge-discharge cycling and enhanced the cycle stability of the electrode. More importantly, this is a significant study to directly use LDHs as a potential electrode for LIBs, which can promote applications of electro-active LDHs in energy storage and conversion fields.
高性能且易于制备的电极材料对于获得高效的锂离子电池（LIBs）至关重要。在本研究中，首次制备了石墨烯包裹的 CoNi 层状双氢氧化物（LDH）微球，并将其用作 LIBs 的阳极材料。质量比为 2.5：1（CoNi-LDH/石墨烯）的复合电极在 0.05 A g-1 时具有高达 1428.0 mA h g-1 的可逆比容量，具有优异的倍率性能（分别在 0.5、2 和 10 A g-1 时为 977.5、670.8 和 328.1 mA h g-1）和长循环性能（在 10 A g-1 下循环 10000 次后保持 75%的容量）。优异的电化学性能可归因于以下原因：CoNi-LDH 具有高化学反应性，石墨烯壳提高了 CoNi-LDH 的导电性，从而促进了电荷转移；石墨烯壳还抑制了充放电循环过程中金属氢氧化物的体积膨胀，增强了电极的循环稳定性。更重要的是，这是一项重要的研究，可直接将 LDHs 用作 LIBs 的潜在电极，从而促进电活性 LDHs 在储能和转换领域的应用。
