Insights into Changes in Voltage and Structure of Li2FeSiO4 Polymorphs for Lithium-Ion Batteries
Insights into Changes in Voltage and Structure of Li2FeSiO4 Polymorphs for Lithium-Ion Batteries
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DOI：
10.1021/cm300749w
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发表时间：
2012-06-12
影响因子：
8.6
通讯作者：
Islam, M. S.
中科院分区：
文献类型：
--
作者：
Eames, C.;Armstrong, A. R.;Islam, M. S.
寻找新的低成本、安全和高容量的锂电池阴极最近将注意力集中在Li 2FeSiO 4上。该材料具有挑战性，因为它表现出复杂的多晶型，并且当其电化学循环时，与结构变化相关的电池电压显著下降。基于密度泛函理论技术的系统研究已经进行，以检查电池电压和结构的变化，为全范围的Li 2FeSiO 4多晶型物（β（II），γ（S）和γ（II）），包括新阐明的循环结构（称为逆β（II））。我们发现，循环结构具有0.18-0.30 V的电压比直接合成的多晶型物在雅阁与实验观察。电池电压的趋势与从Li 2FeSiO 4到LiFeSiO 4的脱锂时的能量变化相关，其中阳离子-阳离子静电排斥与四面体框架的扭曲竞争。
The search for new low cost, safe, and high capacity cathodes for lithium batteries has focused attention recently on Li2FeSiO4. The material presents a challenge because it exhibits complex polymorphism, and when it is electrochemically cycled there is a significant drop in the cell voltage related to a structural change. Systematic studies based on density functional theory techniques have been carried out to examine the change in cell voltages and structures for the full range of Li2FeSiO4 polymorphs (beta(II), gamma(s), and gamma(II)) including the newly elucidated cycled structure (termed inverse-beta(II)). We find that the cycled structure has a 0.18-0.30 V lower voltage than the directly synthesized polymorphs in accord with experimental observations. The trends in cell voltage have been correlated to the change in energy upon delithiation from Li2FeSiO4 to LiFeSiO4 in which the cation-cation electrostatic repulsion competes with distortion of the tetrahedral framework.