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Neat Design for the Structure of Electrode To Optimize the Lithium-Ion Battery Performance

Zhao, Yongjie, Ding, Caihua, Hao, Yanan, Zhai, Ximei, Wang, Chengzhi, Li, Yutao, Li, Jingbo, Jin, Haibo
ACS applied materials & interfaces 2018 v.10 no.32 pp. 27106-27115
X-ray diffraction, anisotropy, electrodes, energy, freeze drying, graphene, lithium, lithium batteries, milling, nanoparticles, scanning electron microscopy, shrinkage, synergism, transmission electron microscopy
The appearance of mechanical cracks originated from anisotropic expansion and shrinkage of electrode particles during Li⁺ de/intercalation is a major cause of the capacity fading in Li-ion batteries. Well-designed and controlled nanostructures of electrodes have shown a prominent prospect for solving this obstacle. Here, we report a novel and convenient strategy for the preparation of graphene nanoscroll wrapping Nb₂O₅ nanoparticles (denoted as T-Nb₂O₅/G). First, high energy ball milling is conducted to acquire softly agglomerated T-Nb₂O₅ nanoparticles owing to its spontaneous reduction of surface energy among these single particles. Then freeze-drying leads to the formation of graphene nanoscroll, which easily realizes the in situ wrapping over softly agglomerated T-Nb₂O₅ nanoparticles. Extended cycling tests demonstrate that such T-Nb₂O₅/G yields a high reversible specific capacity of 222 mA h g–¹ over 700 cycles at 1C. The dominated surface capacitive insertion processes possessing favorable kinetics enable T-Nb₂O₅/G to exhibit excellent rate performance, which achieve a capacity of 110 mA h g–¹ at 10C. A combined ex situ X-ray diffraction, scanning electron microscopy, and transmission electron microscopy investigation reveal that the long-term cycling stability of T-Nb₂O₅/G is attributed to the excellent structural stability of the electrode, in which the synergistic effect between the softly agglomerated T-Nb₂O₅ nanoparticles and graphene nanoscroll prevents the formation of mechanical cracks.