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Yongfeng, China

Gong X.,Jiangxi Normal University | Huang J.,Jiangxi Normal University | Chen Y.,Jiangxi Normal University | Wu M.,Jiangxi Normal University | And 9 more authors.
International Journal of Electrochemical Science | Year: 2013

Although density functional theory has played important role in designing electrode materials for lithium ion batteries, it fails in correctly prediction of temperature dependant parameters of performance of the battery system that is more relevant in application. To simulate the temperature dependence of the thermodynamic parameters, the lattice vibrational energy should be included. In this paper, we calculated the lattice vibrational dynamic properties of the LiCoO2/Li half battery system. We found that there is no imaginary frequency appeared when all Li atoms are removed, indicating that the bulk structure is stable upon Li removal. Furthermore, the vibration frequency of Co atom along the ab-plane is substantially increased after lithium is removed, due to the strengthened Co-O bonds. The vibrational entropy of the LiCoO2 and its delithiated state Li□CoO2 is very close to each other. We show that the intercalation potential of the battery is altered noticeable when the lattice vibrational contribution is included. © 2013 by ESG.

Huang J.,Jiangxi Normal University | Wang Z.,Jiangxi Normal University | Gong X.,Jiangxi Normal University | Wu M.,Jiangxi Normal University | And 10 more authors.
International Journal of Electrochemical Science | Year: 2013

Silicon is one important candidate as anode materials for next generation lithium ion batteries because of its extremely high specific capacity (4200mAh/g). In this paper, we show from first principles calculations that vacancies play important role in the beginning of the lithiation process of crystalline silicon. Without vacancy, the Li binding energy is lower than that of Li metal, indicating that lithium can not be intercalated into crystalline Si. On the other hand, vacancies can enhance the binding energy substantially and make the lithium intercalation process thermodynamically favorable during the initial stage of the discharge process. © 2013 by ESG.

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