High-performance Li-ion batteries are urgently demanded for portable electronics and new energy electric vehicles. As the key part of batteries, active materials are commonly required to have high capacity, large energy density, long cycling stability and good safety. In order to achieve a high capacity and energy density, the portion of active materials within the electrode should be maximal, while excellent electron transfer and ion diffusion performances are essential for good stability and safety. 3D nanostructured materials are promising to meet those requirements. However, conventional 3D battery materials contain metal or some other high-density materials as scaffold to support the whole structure, which reduces the percentage of active materials and decreases the capacity of full cell, and this is a restrict factor of long-term cycling stability.

Significant research progresses on high-performance graphene-based Li-ion batteries have been accomplished by associate professor LIU Jinyun who is a member of Prof. LIU Jinhuai and Prof. HUANG Xingjiu’s group at Institute of Intelligent Machines, Hefei Institutes of Physical Science. Three-dimensional (3D) graphene-based Li-ion battery nanocomposites with high capacity and long cycling life were deceloped in their research. Research findings have been published in Advanced Materials (http://onlinelibrary.wiley.com/doi/10.1002/adma.201670247/full). This article titled Graphene Sandwiched Mesostructured Li-Ion Battery Electrodes was selected as a frontispiece article of the journal.

On the basis of the collaboration between University of Illinois at Urbana-Champaign and Hefei Institutes of Physical Sciences, LIU and his colleagues developed a 3D graphene-based battery composite, which showed high loading of active materials and short pathway for ion and electron transfer. Besides, there was no need of additives such as binders and conductive additives to assemble the presented materials into batteries. Those features made the battery possess a high capacity and good cycling stability. The prepared 3D graphene/V₂O₅ cathode exhibited a capacity higher than 200 mAh/g after 2000 cycles at 5C (about 12 min for one charge or discharge). Most of the previous reports showed a cycling time was less than 1000 cycles, while the capacity less than 150 mAh/g. To achieve a capacity of the graphene/V₂O₅ cathode charged for 1 min, the commercial electrodes and previous reports require longer than 5 min.

In addition, the presented 3D graphene-based nanocomposites design can also be applied to the battery anode preparation, such as graphene/Si anodes, showing a good general applicability.

Figure 1. Cross-sectional SEM image of the 3D graphene/V₂O₅ cathode (Frontispiece of Advanced Materials); (b) SEM image of 3D graphene; (c) Charge-discharge curves (5C for 2000 cycles)