Structural, Electronic, and Electrochemical Properties of Cathode Materials Li2MSiO4 (M = Mn, Fe, and Co): Density Functional Calculations

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• 作者：Guohua Zhong ; Yanling Li ; Peng Yan ; Zhuang Liu ; Maohai Xie ; Haiqing Lin
• 刊名：Journal of Physical Chemistry C
• 出版年：2010
• 出版时间：March 4, 2010
• 年：2010
• 卷：114
• 期：8
• 页码：3693-3700
• 全文大小：496K
• 年卷期：v.114,no.8(March 4, 2010)
• ISSN：1932-7455

文摘

For Li₂FeSiO₄, its P2₁ space group makes it possibly perfect as a new cathode material for Li-ion batteries (Nishimura et al. J. Am. Chem. Soc. 2008, 130, 13212). For this type of Li₂MSiO₄ (M = Mn, Fe, and Co), the structural, electronic, and electrochemical properties have been investigated, using the density functional theory with the exchange-correlation energy treated as the generalized gradient approximation (GGA) plus on-site Coulomb energy correction (+U). Within the GGA+U framework, the fully lithiated Li₂MSiO₄ as well as the delithiated LiMSiO₄ and MSiO₄ are all semiconducting, and the band gap lowers with the extraction of lithium ions. The fully lithiated compounds are all stabilized at their ferromagnetic phase, while the delithiated compounds are all stabilized when antiferromagnetic. Starting from the P2₁ structure, the fully delithiated MSiO₄ has better stability than that obtained from Pmn2₁ structure. In Li₂FeSiO₄, the possibility of reversibly extracting more than one lithium ion is enhanced because of the lower stability of the intermediate phase LiFeSiO₄ comparing with the Pmn2₁ symmetry situation. Li₂MnSiO₄ with the P2₁ symmetry has higher electronic conductivity, and Li₂CoSiO₄ has the suitable second-step voltage of less than 5.0 V. All Li₂FeSiO₄, Li₂MnSiO₄, and Li₂CoSiO₄ are predicted as promising cathode materials.