Al2O3含量对放电等离子烧结Al_(2)O_(3)/Cu复合材料组织与性能的影响

以微米级Cu粉为基体相,纳米Al_(2)O_(3)颗粒为绝缘相,采用机械球磨和放电等离子烧结工艺相结合的方法制备Al_(2)O_(3)/Cu复合材料,研究Al_(2)O_(3)含量对复合材料微观结构、电阻率和热导率的影响。结果表明,Al_(2)O_(3)/Cu复合材料为核−壳结构,随Al_(2)O_(3)含量增加,Al_(2)O_(3)包覆层对Cu基体的包覆效果逐渐提升;当w(Al_(2)O_(3))为5%时,Al_(2)O_(3)/Cu复合材料的热导率较高,为85.92 W/(m·K),但电阻率偏低,仅为12.6 mΩ·cm。当w(Al_(2)O_(3))增加至15%时,虽然Al_(2)O_(3)/Cu复合材料的密度降至6.69 g/cm^(3),孔隙率较高,但电阻率显著提高至2.09×10^(8) mΩ·cm,约为Cu电阻率的10^(11)倍,且热导率为7.6 W/(m·K),明显高于传统金属基板的热导率。

三元锂电池储能性能与工作环境温度关系研究

通过对三元锂电池分别进行充/放电容量测试,并结合脉冲实验,研究了三元锂电池在不同环境温度下的储能性能。结果表明,在放电过程中,随着环境温度从55℃降至-10℃,放电平台电压降低,放电容量减少。在高温(55℃)下放电容量是额定容量的105.0%,在低温(-10℃)下放电容量仅为额定容量的83.9%。随着环境温度降低,电池产热逐渐增大,内阻升高,放电功率减小,影响电池的正常使用。在充电过程中,随着环境温度从55℃降至-10℃,充电平台电压升高,内阻和充电功率升高,影响电池充电效率。

微波热压优化分层微观结构BixSb2−xTe3合金的热电性能

通过机械合金化结合微波活化热压新技术(MAHP)制备分层结构的p型BixSb2−xTe3(x=0.30,0.35和0.40,质量分数)合金,研究Bi含量对BixSb2−xTe3合金组织与热电性能的影响。结果表明,合金中存在不规则纳米颗粒,为原位纳米结构,是由微波电弧效应引起的。随Bi含量增加,载流子浓度明显降低,使得电阻率和塞贝克系数增加。同时,由于不规则纳米颗粒减少,合金的晶格热导率增加。Bi0.3Sb1.7Te3具有最大功率因子3.81 mW/(m·K^2)和最小晶格热导率0.33 W/(m·K),从而在70℃时获得最大的无量纲热电优值1.23。本研究引入的MAHP技术具有明显提升BixSb2−xTe3合金热电性能的效果。

Improvement of Thermoelectric Performance in BiCuSeO Oxide by Ho Doping and Band Modulation

We try to use Ho doping combined with band modulation to adjust the thermoelectric properties for BiCuSeO.The results show that Ho doping can increase the carrier concentration and increase the electrical conductivity in the whole temperature range.Although Seebeck coefficient decreases due to the increase of carrier concentration,it still keeps relatively high values,especially in the middle and high temperature range.On this basis,the band-modulation sample can maintain relatively higher carrier concentration while maintaining relatively higher mobility,and further improve the electrical transporting performance.In addition,due to the introduction of a large number of interfaces in the band-modulation samples,the phonon scattering is enhanced effectively and the lattice thermal conductivity is reduced.Finally,the maximal power factor(PF)of 5.18μW·cm^-1K^-2and the dimensionless thermoelectric figure of merits(ZT)of 0.81 are obtained from the 10%Ho modulation doped sample at 873 K.