Nitrogen-doped zinc/cobalt mixed oxide micro-/nanospheres for high-rate lithium-ion battery anode
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Nitrogen-doped zinc/cobalt mixed oxide micro-/ nanospheres for high-rate lithium-ion battery anode Xiaotao Deng1, Sirui Li2, Jiaqi Wang2, Ding Nan2,a), Junhui Dong2, Jun Liu2,b) 1
Pipeline Design Department, Zhuhai Branch of China Petroleum Pipeline Engineering Co., Ltd., Zhuhai 519015, People’s Republic of China School of Materials Science and Engineering, Inner Mongolia University of Technology, Hohhot 010051, China; and Inner Mongolia Key Laboratory of Graphite and Graphene for Energy Storage and Coating, Hohhot 010051, China a) Address all correspondence to these authors. e-mail: [email protected] b) e-mail: [email protected] 2
Received: 14 May 2019; accepted: 9 August 2019
Metal oxides are promising candidates as the anodes of next-generation lithium ion batteries. However, the low electronic conductivities hinder their practical applications. Herein, through a facile calcination process using ammonium bicarbonate (NH4HCO3) as the N source, the nitrogen heteroelement was introduced into the ZnO/ CoO micro-/nanospheres, which greatly improves the conductivity of the composites. As the lithium-ion battery anode, the N-doped ZnO/CoO micro-/nanosphere demonstrates much enhanced electrochemical performance. It displays a high initial capacity of 911.8 mA h/g at a current density of 0.2 A/g and long-term cycling stability, with a reversible capacity of 977.8 mA h/g remained after 500 cycles at a current density of 1 A/g. Furthermore, the N-doped ZnO/CoO composite presents an outstanding rate performance, with 605 mA h/g remained even at 5 A/g. The excellent electrochemical properties make N-doped ZnO/CoO micro-/nanospheres a promising candidate as high-performance anodes for next-generation rechargeable LIBs.
Introduction Over the past decades, lithium-ion batteries (LIBs) have been regarded as the most significant energy storage devices for portable electronics and hybrid electric vehicles because of their advantages of high working voltage, fast charging/discharging rate, and large energy density [1, 2, 3]. Yet, the low theoretical capacity (372 mA h/g) of commercial graphite electrodes as well as the potential safety issues during cell operation limit their large-scale energy storage applications. Besides, the lithiation/delithiation reactions occurring on electrodes are typically accompanied by sluggish reaction kinetics, also endowing the LIBs with unsatisfactory rate capability. With the ever increasing demand for higher specific energy [4, 5], it is highly desirable to explore novel electrode materials with higher energy storage capacity [6]. Transition metal oxides are one type of promising candidates for next-generation LIB anode materials, and they possess many promising advantages as anodes of LIBs. Firstly, the theoretical capacities of metal oxides are higher than that of graphite; some are even approaching 1000 mA h/g, which is about 2–3 times higher than that of graphite. Secondly, the densities of metal oxides are
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also higher than that of graphite. For instance, th
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