Preparation and electrochemical evaluation of NiO nanoplatelet-based materials for lithium storage
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ng Wang National Key Laboratory of Photoelectric Technology and Functional Materials (Culture Base), National Photoelectric Technology and Functional Materials & Application International Cooperation Base, Institute of Photonics & Photon-Technology, Northwest University, Xi’an 710069, People’s Republic of China
Gaohong Zhai and Hui Wanga) Key Laboratory of Synthetic and Natural Functional Molecule Chemistry (Ministry of Education), College of Chemistry & Materials Science, Northwest University, Xi’an 710069, People’s Republic of China (Received 29 March 2014; accepted 17 June 2014)
NiO nanoplatelet-based materials with different dimensionality are synthesized by a one-step hydrothermal route at 120 °C for 4 h. The morphologies and structure of the obtained NiO nanoplatelets grown on Ni foam and NiO microspheres composed of nanoplatelets are characterized. The results show that the former has a length of 5–10 lm and a uniform thickness of ;100 nm, while the latter has a diameter of 5–10 lm. Their electrochemical properties as anode materials for lithiumion batteries are evaluated and compared. The discharge capacities of NiO nanoplatelet electrode are 663, 516, 370, 258, and 169 mAh g1 at current densities of 250, 500, 1000, 2500, and 5000 mA g1, respectively. Such a lithium storage capability is much higher than that of the NiO microsphere electrode. The reasons for the enhanced electrochemical performance of the nanoplatelet electrode were investigated, which suggested that more active sites for electrochemical reactions and faster ion/electron transfer realized on nanoplatelets are facilitating lithium storage.
I. INTRODUCTION
The development of efficient energy storage systems is an emerging requirement to meet the needs of modern society and ecological concerns.1–3 Lithium-ion batteries have been receiving worldwide attention due to their unique characteristics in terms of high energy density and long cycle life. However, energy density and rate capability of current generation lithium-ion batteries are limited by traditional electrode materials.4–6 In recent years, transition metal oxides have been regarded as high capacity anode materials, which may have potential application in future lithium-ion battery systems.7–13 As one of the transition metal oxide anode materials, nickel oxide (NiO) has recently been investigated as an anode for lithium-ion batteries due to its high theoretical capacity (718 mAh g1), low toxicity, ease of fabrication, and low cost.14 However, like other transition metal oxides, large volume change and severe particle aggregation commonly lead to NiO electrode pulverization and loss of inter-particle contact, resulting in a rapid capacity fading and poor cycling stability during repeated discharge–charge
process. For the past several years, several efforts have been made to alleviate these intrinsic problems.15–17 Because the capacity of NiO is generally concerned with their structures, designing the architectures of NiO with controlled shapes in micro/nano-size is regarded as an e
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