Heat capacities and an updated thermodynamic model for the Li-Sn system.
Heat capacities and an updated thermodynamic model for the Li-Sn system.
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DOI：
10.1039/c8cp04205e
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发表时间：
2018-09
期刊：
影响因子：
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通讯作者：
T. Reichmann;Dajian Li;D. Cupid
中科院分区：
文献类型：
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作者：
T. Reichmann;Dajian Li;D. Cupid
在专门设计的Ta坩埚中使用定义的热处理程序合成相纯的Li 17 Sn 4和Li 7Sn 3金属间化合物。通过电感耦合等离子体发射光谱（ICP-OES）和粉末X射线衍射（粉末XRD）技术对产物进行了表征，以确定其组成和相纯度。使用Setaram C80 Tian-Calvet量热计在密封的Ta坩埚中通过分步法测量合成化合物的热容。实验确定的热容量，然后用于开发限制Maier-Kelley模型为每个阶段，并将这些数据到重新优化现有的热力学描述的锂锡系统。新的模型的金属间化合物和液相的结果之间的计算和实验的热容，热力学，电化学和相图数据的改进协议。由于重新优化的吉布斯自由能表达式是基于可靠的热容数据，该模型现在可以用于预测在各种操作温度和活性材料组成的锂锡系统中的电动势值。
Phase-pure Li17Sn4 and Li7Sn3 intermetallic compounds were synthesized using defined heat treatment procedures in specially designed Ta crucibles. The products were characterized by inductively coupled plasma optical emission spectroscopy (ICP-OES) and powder X-ray diffraction (powder-XRD) techniques to determine their composition and phase purity. The heat capacities of the synthesized compounds were measured via the step method in sealed Ta crucibles using a Setaram C80 Tian-Calvet calorimeter. The experimentally determined heat capacities were then used to develop restricted Maier-Kelley models for each phase and to incorporate these data into the re-optimization of an existing thermodynamic description of the Li-Sn system. The new models for the intermetallic and liquid phases result in improved agreement between the calculated and experimental heat capacity, thermodynamic, electrochemical and phase diagram data. Since the re-optimized Gibbs free energy expressions are based on reliable heat capacity data, the models can now be used to predict emf values in the Li-Sn system at a variety of operation temperatures and active material compositions.