采用共沉淀的方法将含有一定比例的镍、钴、锰的醋酸盐溶液均匀混合,然后加入适量的沉淀剂Na_2CO_3制备前驱体Mn_(0.466)Ni_(0.2)Co_(0.2)CO_3,与不同锂源(Li_2CO_3、LiOH)混合煅烧得到富锂锰基Li_(1.133)Mn_(0.466)Ni_(0.2)Co_(0.2)O_2正极材料.采用XRD和SEM分别对制备的(1.133)Mn_(0.466)Ni_(0.2)Co_(0.2)O_22的结构和表面形貌进行表征,采用恒电流充放电和循环伏安法对制备的(1.133)Mn_(0.466)Ni_(0.2)Co_(0.2)O_22的电化学性能进行测试.结果表明,以Li OH为锂源合成的样品在0.1C(1C=250 m A/g)倍率下首次充电比容量和放电比容量分别为330.1 m Ah/g和218.6 m Ah/g,首次库仑效率为66.23%,在1C倍率内表现为优秀的稳定循环比容量特性,但是在2C以及2C以上高倍率循环稳定性不及以Li_2CO_3为锂源合成样品的性能.
As an anode material in lithium ion battery,the Sn-Co/C composite electrode materials have been successfully synthesized by hydrothermal and sol-gel methods,respectively.The resultant composites were mainly composed of Sn-based oxides,nanometer Sn-Co alloy and carbon.Carbon and Co,acting as buffer materials,can accommodate to the large volume change of active Sn during the discharge-charge process,thus improving the cycling stability.Although charge/discharge curves revealed the excellent cycle performance for samples synthesized by both methods,composites obtained by the sol-gel showed a better dispersion effect of nanoparticles on the carbon matrix and possessed much more improved stable capacity with*624.9 mAh g-1over 100 cycles and that by hydrothermal method only exhibited*299.3 mAh g-1.Therefore,the Sn-Co/C composites obtained by sol-gel synthesis method could be a perfect candidate for anode material of Li-ion storage battery.
Xiaoli ZouXianhua HouZhibo ChengYanling HuangMin YueShejun Hu
Carbon-encapsulated Fe3O4 composites were successfully fabricated via hydrothermal method and ex- amined by X-ray diffraction, scanning electron microscopy and transmission electron microscopy. The Fe3O4@C nanocomposite as an anode material with novel structure demonstrated excellent electrochemical performance, with enhanced specific reversible current density of 50 mA/g capacity （950 mAh/g at the after 50 cycles）, remarkable rate capability （more than 650 mAh/g even at the current density of 1,000 mAJg） and good cycle ability with less capacity fading （2.4 % after 50 cycles）. Two factors have been attributed to the ultrahigh electrochemical perfor- mance： Firstly, the 30- to 50-nm spherical structure with a short diffusion pathway and the amorphous carbon layer could not only provide extra space for buffering the volumetric change during the continuous charging-dis- charging but also improve the whole conductivity of the Fe3O4@C nanocomposite electrode; secondly, the syner- gistic effects of Fe304 and carbon could avoid Fe304 direct exposure to the electrolyte and maintain the structural stabilization of Fe3O4@C nanocomposite. It was suggested that the Fe3O4@C nanocomposite could be suitable as analternative anode for lithium-ion batteries with a high ap- plication potential.
采用原位聚合法制备锡酸钴（Co2SnO4）/聚苯胺（PANI）复合负极材料,用XRD、SEM分析物相结构与形貌,对复合材料进行恒流充放电、循环伏安及电化学阻抗谱测试。添加PANI可缓解Co2SnO4在充放电过程中的体积膨胀效应,使Co2SnO4/PANI体系的电子导电率与循环性能得到改善。以100 m A/g的电流在0.01--3.00 V循环,Co2SnO4/PANI复合材料的首次放电比容量为1 234.11 m Ah/g,第80次循环的放电比容量为817.36 m Ah/g。
