Ye Jianchao, Ong Mitchell T, Heo Tae Wook, Campbell Patrick G, Worsley Marcus A, Liu Yuanyue, Shin Swanee J, Charnvanichborikarn Supakit, Matthews Manyalibo J, Bagge-Hansen Michael, Lee Jonathan R I, Wood Brandon C, Wang Y Morris
Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, Livermore, California 94550, USA.
Sci Rep. 2015 Nov 5;5:16190. doi: 10.1038/srep16190.
Atomic hydrogen exists ubiquitously in graphene materials made by chemical methods. Yet determining the effect of hydrogen on the electrochemical performance of graphene remains a significant challenge. Here we report the experimental observations of high rate capacity in hydrogen-treated 3-dimensional (3D) graphene nanofoam electrodes for lithium ion batteries. Structural and electronic characterization suggests that defect sites and hydrogen play synergistic roles in disrupting sp(2) graphene to facilitate fast lithium transport and reversible surface binding, as evidenced by the fast charge-transfer kinetics and increased capacitive contribution in hydrogen-treated 3D graphene. In concert with experiments, multiscale calculations reveal that defect complexes in graphene are prerequisite for low-temperature hydrogenation, and that the hydrogenation of defective or functionalized sites at strained domain boundaries plays a beneficial role in improving rate capacity by opening gaps to facilitate easier Li penetration. Additional reversible capacity is provided by enhanced lithium binding near hydrogen-terminated edge sites. These findings provide qualitative insights in helping the design of graphene-based materials for high-power electrodes.
通过化学方法制备的石墨烯材料中普遍存在原子氢。然而，确定氢对石墨烯电化学性能的影响仍然是一项重大挑战。在此，我们报告了用于锂离子电池的氢处理三维（3D）石墨烯纳米泡沫电极具有高倍率容量的实验观察结果。结构和电子表征表明，缺陷位点和氢在破坏sp(2)石墨烯以促进快速锂传输和可逆表面结合方面发挥协同作用，快速电荷转移动力学以及氢处理的3D石墨烯中电容贡献的增加证明了这一点。与实验一致，多尺度计算表明，石墨烯中的缺陷复合体是低温氢化的先决条件，并且在应变域边界处缺陷或功能化位点的氢化通过打开间隙以促进锂更容易渗透，在提高倍率容量方面发挥有益作用。氢封端边缘位点附近增强的锂结合提供了额外的可逆容量。这些发现为帮助设计用于高功率电极的石墨烯基材料提供了定性见解。
