Liu Xiaoheng

Facile synthesis of T-Nb 2 O 5 nanosheets/nitrogen and sulfur co-doped graphene for high performance lithium-ion hybrid supercapacitors

Li-ion hybrid supercapacitors (Li-HSCs) have attracted increasing attention as a promising energy storage device with both high power and energy densities. We report a facile two-step hydrothermal method to prepare the orthorhombic niobium oxide (T-Nb2O5) nanosheets supported on nitrogen and sulfur co-doped graphene (T-Nb2O5/NS-G) as anode for Li-HSCs. X-ray diffraction and morphological analysis show that the T-Nb2O5 nanosheets successfully and uniformly distributed on the NS-G sheets. The T-Nb2O5/NS-G hybrid exhibits great rate capability (capacity retention of 63.1% from 0.05 to 5 A g−1) and superior cycling stability (a low capacity fading of ~6.4% after 1000 cycles at 0.5 A g−1). The full-cell consisting of T-Nb2O5/NS-G and active carbon (AC) results in high energy density (69.2 W h kg−1 at 0.1 A g−1), high power density (9.17 kW kg−1) and excellent cycling stability (95% of the initial energy after 3000 cycles). This excellent performance is mainly attributed to the highly conductive NS-G sheets, the uniformly distributed T-Nb2O5 nanosheets and the synergetic effects between them. These encouraging performances confirm that the obtained TNb2O5/ NS-G has promising prospect as the anode for Li-HSCs.摘要锂离子混合电容器, 作为一种同时具有高功率密度和高能量密度的新型储能器件已经受到越来越多的关注. 本文通过简单的两步水热 法制备出T-Nb2O5/N,S 共掺杂石墨烯(T-Nb2O5/NS-G), 作为锂离子混合电容器的负极材料. 通过XRD和形貌表征证明了T-Nb2O5纳米片均匀负 载在掺杂石墨烯上. 测试表明, 该材料具有优异的倍率性能(0.05到5 A g−1容量保持63.1%)和循环稳定性(0.5 A g−1时循环1000次容量只下降 ~6.4%). 用该材料作为负极, 活性炭作为正极组装的锂离子电容器具有高能量密度(0.1 A g−1 时69.2 W h kg−1), 高功率密度(9.17 kW kg−1) 和 优异的循环稳定性(3000次循环后能量密度保持95%). 这些优异的性能主要是由于掺杂石墨烯的高导电性, T-Nb2O5纳米片均匀分布, 以及二 者之间的协同效应. 因此, 该复合材料T-Nb2O5/NS-G是一种高性能的锂离子混合电容器负极材料.