Abstract：NiO hollow microspheres with micro-nano hierarchical structure were synthesized using lysine as the structure regulator, nickel chloride and ammonia as raw materials through hydrothermal synthesis and calcination method. The microstructure and phase composition of NiO materials were characterized by scanning electronic microscopy (SEM), transmission electron microscope (TEM), X-ray diffraction (XRD) and other detection methods. The results show that the prepared hierarchical NiO hollow microspheres with different sizes are well distributed, and the particle size is about 2-3 μm, which is stacked by of many NiO nanosheets. The length of the NiO flakes with clear edges is about 400-600 nm, while the thickness is only about 40-50 nm. Excellent dispersibility and spherical morphology of NiO microspheres can be obtained with addition of 0.6 g lysine at the reaction temperature of 40 ℃ as well as the hydrothermal time of 6 h. In addition, the obtained NiO sphere is hollow, with many flakes stacked and crossed to form a hierarchical structure. Such a unique structure can provide high porosity and specific surface area as well as open channels, all of which are beneficial to the diffusion and migration of both electrolyte ions and electrons. As working electrode, the specific capacitance of the prepared hierarchical NiO hollow microspheres can reach 1 340 F/g in the current density of 1 A/g using the three electrode system and after 1 000 cycles, and the capacity retention rate is 96.5%, showing superior electrochemical performance.
[1] CHANG S P, ZHU J, HUANG S J, et al.New energy materials and device application[J]. International Journal of Photoenergy, 2015, 2015(1): 1-1. [2] RUIZ V, PANDOLFO A G.Polyfurfuryl alcohol derived activated carbons for high power electrical double layer capacitors[J]. Electrochimica Acta, 2010, 55(25): 7495-7500. [3] THOUNTHONG P, RA L S, DAVAT B.Control strategy of fuel cell/supercapacitors hybrid power sources for electric vehicle[J]. Journal of Power Sources, 2006, 158(1): 806-814. [4] INGRAM M D, STAESCHE H, RYDER K S.‘Ladder-doped’ polypyrrole: A possible electrode material for inclusion in electrochemical supercapacitors?[J]. Journal of Power Sources, 2004, 129(1): 107-112. [5] WANG J, ZHANG Y, WAN P, et al.Nanosheet-assembled hollow NiO ball-flower for high-performance supercapacitor[J]. Journal of Materials Science: Materials in Electronics, 2016, 27(8): 8020-8026. [6] VELLACHERI R, PILLAI V K, KURUNGOT S.Hydrous RuO2-carbon nanofiber electrodes with high mass and electrode-specific capacitance for efficient energy storage[J]. Nanoscale, 2012, 4(3): 890-896. [7] LEE J W, AHN T, KIM J H, et al.Nanosheets based mesoporous NiO microspherical structures via facile and template-free method for high performance supercapacitors[J]. Electrochimica Acta, 2011, 56(13): 4849-4857. [8] KUMAR R, SINGH R K, SAVU R, et al.Microwave-assisted synthesis of void-induced graphene-wrapped nickel oxide hybrids for supercapacitor applications[J]. Rsc Advances, 2016, 6(32): 26612-26620. [9] YANG M, LI J X, LI H H, et al.Mesoporous slit-structured NiO for high-performance pseudocapacitors[J]. Physical Chemistry Chemical Physics, 2012, 14(31): 11048-11052. [10] DHARMARAJ N, PRABU P, NAGARAJAN S, et al.Synthesis of nickel oxide nanoparticles using nickel acetate and poly(vinyl acetate) precursor[J]. Materials Science & Engineering B, 2006, 128(1/3): 111-114. [11] LIANG Z H, YINGJIE ZHU A, HU X L.β-Nickel hydroxide nanosheets and their thermal decomposition to nickel oxide nanosheets[J]. Cheminform, 2004, 35(22): 3488-3491. [12] LI Y, TAN B, WU Y.Ammonia-evaporation-induced synthetic method for metal (Cu,Zn,Cd,Ni) hydroxide/oxide nanostructures[J]. Chemistry of Materials, 2008, 20(7): 567-576. [13] WANG, XIONG, LI L, YAN'GE ZHANG, et al. High-yield synthesis of NiO nanoplatelets and their excellent electrochemical performance[J]. Crystal Growth & Design, 2006, 6(9): 2163-2165. [14] XI W, YU L, PENG H, et al.Synthesis of single-crystalline hollow octahedral NiO[J]. Crystal Growth & Design, 2012, 7(12): 2415-2418. [15] WANG C, XU J, YUEN M F, et al.Hierarchical composite electrodes of nickel oxide nanoflake 3D graphene for high-performance pseudocapacitors[J]. Advanced Functional Materials, 2015, 24(40): 6372-6380. [16] BIJU V, KHADAR M A.AC conductivity of nanostructured nickel oxide[J]. Journal of Materials Science, 2001, 36(24): 5779-5787. [17] LI X, LIU G, DONG X, et al.Research progress for various morphologies of nanomaterials with amino acids-assisted synthesis[J]. Chemistry, 2011, 74(4): 325-332. [18] BAGGETTO L, DUDNEY N J, VEITH G M.Surface chemistry of metal oxide coated lithium manganese nickel oxide thin film cathodes studied by XPS[J]. Electrochimica Acta, 2013, 90(5): 135-147. [19] LIANG K, TANG X, HU W.High-performance three- dimensional nanoporous NiO film as a supercapacitor electrode[J]. Journal of Materials Chemistry, 2012, 22(22): 11062-11067. [20] CAO P, WANG L, XU Y, et al.Facile hydrothermal synthesis of mesoporous nickel oxide/reduced graphene oxide composites for high performance electrochemical supercapacitor[J]. Electrochimica Acta, 2015, 157(3): 59-68. [21] SONAVANE A C, INAMDAR A I, SHINDE P S, et al.Efficient electrochromic nickel oxide thin films by electrodeposition[J]. Journal of Alloys & Compounds, 2010, 489(2): 667-673. [22] XING, WEI A L I, YAN L, et al. Synthesis and characterization of mesoporous nickel oxide and its application to electrochemical capacitor[J]. Acta Chimica Sinica-Chinese Edition-, 2005, 63(19): 1775-1781. [23] YU C, ZHANG L, SHI J, et al.A simple template-free strategy to synthesize nanoporous manganese and nickel oxides with narrow pore size distribution, and their electrochemical properties[J]. Advanced Functional Materials, 2010, 18(10): 1544-1554. [24] YAO M, HU Z, XU Z, et al.High-performance electrode materials of hierarchical mesoporous nickel oxide ultrathin nanosheets derived from self-assembled scroll-like α-nickel hydroxide[J]. Journal of Power Sources, 2015, 273(9): 14-22. [25] GAO Y, CHEN S, CAO D, et al.Electrochemical capacitance of Co3O4 nanowire arrays supported on nickel foam[J]. Journal of Power Sources, 2010, 195(6): 1757-1760. [26] LI X, LIU G, DONG X, et al.Research progress for various morphologies of nanomaterials with amino acids-assisted synthesis[J]. Chemistry, 2011, 74(4): 325-332. [27] 徐基贵, 朱军, 史洪伟. L-赖氨酸对CaCO3晶型和形状调控[J]. 合肥工业大学学报: 自然科学版, 2011, 34(6): 924-926. XU Jigui, ZHU Jun, SHI Hongwei.Shape and morphology of CaCO3 crystal controlled by L-lysine[J]. Journal of Hefei University of Technology: Natural Science, 2011, 34(6): 924-926. [28] JIANG H, ZHAO T, LI C, et al.Hierarchical self-assembly of ultrathin nickel hydroxide nanoflakes for high-performance supercapacitors[J]. Journal of Materials Chemistry, 2011, 21(11): 3818-3823. [29] 任丽英, 张群, 朱万华, 等. 仿生合成碳酸钙微环[J]. 人工晶体学报, 2015, 44(1): 250-255. REN Liying, ZHANG Qun, ZHU Wanhua, et al.Biomimetic synthesis of CaCO3 microrings[J]. Rengong Jingti Xuebao/ Journal of Synthetic Crystals, 2015, 44(1): 250-255. [30] XIA L, LIU G, DONG X, et al.Research Progress for Various Morphologies of Nanomaterials with Amino Acids-assisted Synthesis[J]. Chemistry Bulletin, 2011, 74(4): 325-332. [31] MING W, SHAO Z, LENG B, et al.Growth of calcium carbonate mediated by slowly released alginate[J]. Crystengcomm, 2010, 12(3): 730-736. [32] YANG X D, SHEN Q, XU G.Crystallization of calcium carbonate using water-soluble macromolecules[J]. Acta Physico- Chimica Sinica, 2010, 26(8): 2087-2095. [33] ZHU S, DAI Y, HUANG W, et al.In situ preparation of NiO nanoflakes on Ni foams for high performance supercapacitors[J]. Materials Letters, 2015, 161(8): 731-734. [34] LECOEUR C, DAFFOS B, LIN R, et al.Self-standing electrochemical double layer capacitors for operation in severe temperature conditions[J]. Materials for Renewable and Sustainable Energy, 2013, 2(2): 13-16. [35] ZHOU G M, WANG D W, FENG L I, et al.The effect of carbon particle morphology on the electrochemical properties of nanocarbon/polyaniline composites in supercapacitors[J]. New Carbon Materials, 2011, 26(3): 180-186. [36] HALL P J, MIRZAEIAN M, FLETCHER S I, et al.Energy storage in electrochemical capacitors: designing functional materials to improve performance[J]. Energy & Environmental Science, 2010, 3(9): 1238-1251. [37] YE H, CHENG Y, HOBSON T, et al.Design and synthesis of hierarchical MnO2 nanospheres/carbon nanotubes/conducting polymer ternary composite for high performance electrochemical electrodes[J]. Nano Letters, 2010, 10(7): 2727-2733.
2018, Vol. 23 
