电化学阳极沉积奈米结构氧化镍电极应用于锂离子二次电池负极材料.DOCVIP

中文摘要 本研究主要是利用電化學陽極沉積法在不銹鋼基材上沉積多孔性奈米結構氧化鎳電極，做為鋰離子電池負極材料使用。此外為了提升電極的電化學特性，以電泳動沉積法製備聚苯乙烯(PS)球狀模板後再進行陽極沉積氧化鎳，經移除聚苯乙烯球及燒結後可得巨孔結構(500 nm)氧化鎳電極，並探討此巨孔電極在鋰離子電池負極材料的電化學特性。 由電子顯微鏡(SEM)圖可以發現電沉積後的氧化鎳薄膜為一種奈米網狀結構，當使用較大的沉積電流密度時(0.25 mA cm-2)，其形成網狀結構的孔洞會比小電流沉積(0.05 mA cm-2)的略小。但經過充放電後，電極表面會產生劇烈變化，反而較大電流密度沉積的電極還保有多孔性，而較小電流密度沉積的電極其孔隙度會大幅減少。從氧化鎳電極的1 C充放電曲線圖可知，以0.05與0.25 mA cm-2電沉積之氧化鎳薄膜電極，其可逆電容量分別為1221與1294 mAh g-1，當在大電流速率充放電測試(15 C)時，其可逆電容量分別為383與487 mAh g-1，明顯的反而以0.25 mA cm-2沉積具有較優異的電化學性能。 以PS當模板所製備的巨孔結構氧化鎳電極(沉積電流密度為0.25 mA cm-2)，其可逆電容量可提升15.6 %，更重要的是當以大電流速率充放電(15 C)測試時，其可逆電容量可大幅提升87 %。這顯示用PS當模板所形成的巨孔結構氧化鎳電極，確實增加許多比表面積與反應面積，使得電解液可以更有效且快速進入氧化鎳電極內部進行反應，降低電極材料中的內部電阻，對氧化鎳電極之電化學性能有所提升。 英文摘要 In this research, the nanostructured nickel oxide electrodes were deposited onto the stainless steel (SS) substrate by anodic deposition for lithium-ion battery application. In order to improve the electrochemical performance of the nickel oxide electrode, monodispersed polystyrene (PS) spheres were used as a template in anodic deposition of nickel oxide. The PS template was fabricated by electrophoretic deposition (EPD). After removal of PS, the electrode was annealed at 400oC for 1 h to form macroporous NiO electrode (cubic NiO, deduced from X-ray diffraction). The electrochemical properties of the macroporous NiO electrode toward lithium were investigated. Surface morphology of the deposited NiO electrodes is platelet-like structure observed from SEM (scanning electron microscope). The pores in the electrode deposited at a high current density of 0.25 mA cm-2 are smaller than that of deposited at a lower current density of 0.05 mA cm-2. However, the surface morphology of nickel oxide electrode can be severely modified after charge and discharge cycling. The porous structure of the electrode deposited at 0.25 mA cm-2 remains unchanged, while that of deposited at 0.05 mA cm-2 is attenuated significantly. Galvanostatic charge/discharge curve of nickel oxide films (1 C current) indicates that the rever