【作者】 成月；

【导师】 童庆松；

【作者基本信息】 福建师范大学 ， 物理化学， 2007， 硕士

【摘要】 锡负极是锂离子电池潜在的负极材料，理论比容量达到990 mAh／g。然而，在充放电过程中锡负极的体积膨胀率较大，长期循环后会产生粉化现象，导致循环性能较差，特别是首次循环的不可逆容量较大。为了改善锡阳极的电化学性能，本文试图通过活性／非活性复合合金的办法制备锡铜基合金，开展以下几方面的研究工作，取得具有创新性的成果。第一，在不同组成的碱性镀液中，于铜膜电极上电沉积金属锡膜，然后再将制备的电极在氩气气氛中，于不同温度烧结处理。采用XRD、TG-DTA、EIS、AFM、SEM及充放电循环实验等现代方法研究了制备条件对样品电化学性能的影响。实验结果显示：在本文的实验条件下，锡酸钠含量为60g／L时，制备的锡铜合金电极的电化学性能最好。在280℃烧结的锡铜合金具有单斜Cu₆Sn₅（C2／c空间群）结构，晶胞体积较大，在充放电中结构稳定。在0.03～2.0 V电压区间充放电时，首次放电容量为503 mAh／g，40循环的容量衰减率为33％。第二，将电沉积于铜膜电极上的金属锡膜置于空气流和氩气流的混合气氛中，首次采用混合气氛烧结法制备。当空气流速和氩气流速比为4：24时，于380℃烧结制得锡铜合金复合氧化膜。该样品的首次放电容量为1451 mAh／g，40次循环充放电后，放电容量仍保持在600 mAh／g以上。第三，首次在锡铜合金上进一步覆盖镍钴合金膜，采用不同温度处理合成样品。充放电实验表明，230℃为最佳烧结温度。该样品首次放电容量为408 mAh／g，首次充放电效率高达80％。掺杂降低了首次不可逆容量损失。通过优化组成，当制备样的锡和镍钴合金质量比为6：1时的样品有最佳的电化学性能。更多还原

【Abstract】 Tin is a potential anodic material used for lithium ions batteries for its hightheoretical capacity of 990 mAh/g. However, during charge and discharge process, thevolume-expanding ratio of the tin anode is too large to produce good cycling performanceduring charge-discharge test. And the sample is to become the powdered alloy afterlong-term tested. To improve the electrochemical performance of the tin alloy, thisdissertation is planning to prepare the Cu and Sn alloys by adopting the methods of theactivity/non-activity composite alloy. The research work included the several aspectsblow.Firstly, by sintered the tin-copper films eleetroplated from the alkaline solutions atdifferent temperatures, several kinds of tin-copper alloys were prepared XRD, TG-DTA,Electrochemical impedance, AFM, SEM and charge-discharge test were employed tostudy the effect of preparation condition on the electrochemical performance of thesamples. The research results showed that the coating behavior is optimum when thesodium stannate concentration is 60 g/L. The as-prepared sample shows the bestelectrochemical properties in all samples. The tin-copper alloy sintered at 280℃with amonoclinic structure of Cu₆Sn₅ （Space group: C2/c） exhibits a large crystal and the stablestructure during charge-discharge cycles. The sample exhibits a discharge capacity of 503mAh/g in the 1st cycle and the capacity fading rate is 33 % in 40 cycles in the voltageregion from 0.03 to 2.0 V.Secondly, the tin films coated on the copper film sintered at 380℃in the mixingatmosphere of the 4:24 ratio of airflow and argon flow. The sintered product is composedof the tin-copper alloy coated with the composite oxide film. The first cycle dischargecapacity of this sample is 1451 mAh/g. After 40 cycles, its capacity is higher than 600mAh/g.Thirdly, a SnCuNiCo alloy sample was firstly prepared by sintered the as-preparedsample consisted of the tin-copper alloy coated with nickel-cobalt alloy. Thecharge-discharge results showed that the best-sintered temperature is 230℃. The firstcycle discharge capacity of the sample is 408 mAh/g and its charge-discharge efficiency at the 1st cycle is 80%, which result shows that the doping reduced the capacity loss. Theoptimization synthesis condition is the 6:1 mass ratio between tin and nickel-cobalt.更多还原