【作者】 冯忠厚；

【导师】 韩树民； 刘玉文；

【作者基本信息】 燕山大学 ， 应用化学， 2009， 硕士

【摘要】 Co（OH）₂作为二次电池的重要添加剂,其制备方法和电化学性能受到广泛的关注。然而,传统的制备方法存在生产环节多、过滤困难、易氧化等缺点,因此,采用室温固相反应法制备了β–Co（OH）₂,利用X射线衍射（XRD）,场发射扫描电镜（FE–SEM）,热重（TG）分析等方法分析了β–Co（OH）₂的相结构、表面形貌和热失重情况。研究了β–Co（OH）₂电极的电化学性能,以及物理掺杂对Co（OH）₂电极电化学性能的影响,并讨论了其作为电极材料的可能性。XRD和TG分析表明所制备的样品为β–Co（OH）₂,属于六方晶系,纯净无杂质。FE–SEM表明样品粒度小于500 nm。电化学测试表明,β–Co（OH）₂电极经过2周循环即可活化,最大放电容量可达到466 mAh/g。同时,β–Co（OH）₂电极具有良好的高倍率充电性能,1500 mA/g下的高倍率充电性能为83.5%。电极对环境温度变化敏感,在293～333 K之间,电极的放电容量随着温度的升高而增大,放电平台则随着温度的升高而降低。目前存在的主要问题是其放电电压平台较低,在充放电循环时,放电容量有波动。添加剂提高了β–Co（OH）₂电极的高倍率放电性能,提高程度的顺序为石墨>活性炭>La₂O₃>铜粉。添加石墨和La2O3后,电极放电中值电压分别为1156 mV和1150 mV,均明显高于未掺杂电极的放电中值电压（1138 mV）。并且添加剂改善了电极的循环稳定性。更多还原

【Abstract】 Co（OH）₂ as additive of secondary batteries has been attached great importance. Several investigations were focused on the synthesis and the electrochemical properties of Co（OH）₂. However, the traditional preparation methods needs several steps, consuming lots of energy, and even the products is difficult to filtrate and easy to be oxidized. Therefore,β–Co（OH）₂ was synthesized by solid-state reaction and electrochemical properties were tested in this paper. X-ray diffraction （XRD）, Field-emission scanning electron microscope （FE-SEM） and thermal gravity （TG） were employed to determine the microstructure, morphology and weight losing, respectively. Moreover, the effect of additives on electrochemical properties ofβ–Co（OH）₂ electrode was investigated. The possibility of theβ–Co（OH）₂ as the candidate materials for negative electrodes of batteries was discussed.The XRD showed that the as-synthesized sample wasβ–Co（OH）₂ with hexagonal structure. FE-SEM indicated that the size of theβ–Co（OH）₂ powder was less than 500 nm. Theβ–Co（OH）₂ electrode can be activated within 2 cycles and reached the maximum discharge capacity of 466 mAh/g. Theβ–Co（OH）₂ exhibited high rate chargeability. The ratio of HRC1500 vs. HRC60 was 83.5%. Theβ–Co（OH）₂ electrode was sensitived to temperature. From 293 to 333 K, the discharge capacity increases, while the discharge platform descends. The drawbacks ofβ–Co（OH）₂ used as electrode materials were lower discharge platform and undulation of the discharge capacity during charge-discharge cycling.The additives improved the high rate dischargeability ofβ–Co（OH）₂ electrode. The improvement order is graphite>activated charcoal>La2O3>copper powder. The discharge platform is 1156 mV （with graphite） and 1150 mV （with La2O3）, respectively, while that of the blank electrode is 1138 mV. The cycle stability ofβ–Co（OH）₂ with an additive has also been improved.更多还原