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  • Unusual improvement of pseudocapacitance of nanocomposite electrodes: Three-dimensional amorphous carbon frameworks triggered by TiO2 nanocrystals
  • 来源:王海教授个人网站 2020-04-26
  • Both nanocrystals and carbon materials have attracted considerable

    attention in the field of lithium-ion batteries (LIBs), due to their fast

    kinetics for lithium storage or long-life cycles. However, the easy aggregation

    of nanocrystals and high-temperature doping process of carbon materials

    seriously hindered their application in LIBs. Here we report the development of

    unprecedented TiO2-x@C nanocomposite electrodes through a unique

    "melting-low temperature pyrolysis" strategy. It is found that in

    this composite structure, the continuous and interconnected three-dimensional

    amorphous carbon framework (3DCF) was closely connected by TiO2

    nanocrystals by Ti-O-C covalent bonding, forming robust 3D network

    architectures. Interestingly, we found that TiO2 nanocrystals can

    greatly improve the pseudocapacitance of TiO2-x@C nanocomposite

    electrodes with increasing cycles, which significantly exceeded previously

    reported TiO2-based anodes and carbon materials. Furthermore, for

    the first time, the unusual improvement of pseudocapacitance of TiO2-x@C

    electrodes were carefully investigated by means of dQ/dV curves and electrochemical

    kinetic analysis to reveal the extra contribution of lithium storage. 3DCF, a

    “lithium ion reservoir”, possesses an unexpected capacity enhancement behavior

    that is triggered by TiO2 nanocystals, and exhibited bicontinuous

    pathways for both rapid ions and electrons transport.  In this case, TiO2 nanocrystals

    stabilizing 3DCF acted as a conductive agent during charge and discharge. Our findings

    confirm that 3DCF triggered by TiO2 nanocrystals boosted electrochemical

    performance of TiO2-x@C nanocomposite electrodes, especially the

    pseudocapacitance enhancement. The unique characteristics of ingenious

    combination of TiO2 nanocrystals and amorphous carbon materials make

    them obtain superior electrochemical properties in all known TiO2-x

    and carbon-based anodes (289 mAh g-1 at 5 A g-1 after

    4000 cycles). Above all, our findings reveal previously ignored fundamental

    aspects of pseudocapacitance improvement of nanocomposite electrodes, and offer

    new hope for structural design and carbon coating process of high-performance

    anode materials.


  • [来源:中国聚合物网]
  • 了解更多请进入: 王海教授个人网站
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