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A Density Functional Theory Study of the Ionic and Electronic Transport Mechanisms in LiFeBO3 Battery Electrodes
The Journal of Physical Chemistry C ( IF 3.3 ) Pub Date : 2016-08-17 00:00:00 , DOI: 10.1021/acs.jpcc.6b03456 Simon Loftager 1 , Juan María García-Lastra 1 , Tejs Vegge 1
The Journal of Physical Chemistry C ( IF 3.3 ) Pub Date : 2016-08-17 00:00:00 , DOI: 10.1021/acs.jpcc.6b03456 Simon Loftager 1 , Juan María García-Lastra 1 , Tejs Vegge 1
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Lithium iron borate is an attractive cathode material for Li-ion batteries due to its high specific capacity and low-cost, earth-abundant constituents. However, experiments have observed poor electrochemical performance due to the formation of an intermediate phase, that is, LixFeBO3, which leads to large overvoltages at the beginning of charge. Using a convex-hull analysis, based on Hubbard-corrected density functional theory (DFT+U), we identify this intermediate phase as Li0.5FeBO3. Moreover, we show by means of the nudged elastic band (NEB) method, that the origin of these adverse electrochemical effects can be explained by an intrinsically low Li-ion and electron/hole-polaron mobility in Li0.5FeBO3 due to high activation barriers for both the ionic and electronic transport. These studies include the effects of the experimentally reported commensurate modulation. We have also investigated the Li-ion/hole diffusion through the interface between Li0.5FeBO3 and LiFeBO3, which is found not to result in additional kinetic limitations from Li diffusion across the intraparticle interfaces. These findings suggest that the experimentally observed diminished performance associated with the formation of intermediate phases is linked to the intrinsically poor properties of the Li0.5FeBO3 phase rather than to the presence of interfaces between different phases.
中文翻译：
LiFeBO 3电池电极中离子和电子传输机理的密度泛函理论研究
硼酸锂铁由于其高比容量和低成本，富含地球的成分而成为锂离子电池有吸引力的阴极材料。然而，实验已经观察到由于形成中间相Li x FeBO 3而导致的电化学性能差，该中间相导致在充电开始时产生大的过电压。使用基于赫伯校正的密度泛函理论（DFT + U）的凸包分析，我们将该中间相确定为Li 0.5 FeBO 3。此外，我们通过微动弹性带（NEB）方法表明，这些不利的电化学效应的根源可以通过固有的低锂离子和锂中的电子/空穴-极化子迁移率来解释。0.5 FeBO 3归因于离子和电子传输的高活化势垒。这些研究包括实验报告的相应调制的影响。我们还研究了通过Li 0.5 FeBO 3和LiFeBO 3之间的界面发生的Li离子/空穴扩散，发现该现象不会导致Li跨粒子内界面扩散的其他动力学限制。这些发现表明，实验观察到的与中间相形成相关的性能降低与Li 0.5 FeBO 3相固有的不良性能有关，而不是与不同相之间存在界面有关。
更新日期：2016-08-17
中文翻译：
LiFeBO 3电池电极中离子和电子传输机理的密度泛函理论研究
硼酸锂铁由于其高比容量和低成本，富含地球的成分而成为锂离子电池有吸引力的阴极材料。然而，实验已经观察到由于形成中间相Li x FeBO 3而导致的电化学性能差，该中间相导致在充电开始时产生大的过电压。使用基于赫伯校正的密度泛函理论（DFT + U）的凸包分析，我们将该中间相确定为Li 0.5 FeBO 3。此外，我们通过微动弹性带（NEB）方法表明，这些不利的电化学效应的根源可以通过固有的低锂离子和锂中的电子/空穴-极化子迁移率来解释。0.5 FeBO 3归因于离子和电子传输的高活化势垒。这些研究包括实验报告的相应调制的影响。我们还研究了通过Li 0.5 FeBO 3和LiFeBO 3之间的界面发生的Li离子/空穴扩散，发现该现象不会导致Li跨粒子内界面扩散的其他动力学限制。这些发现表明，实验观察到的与中间相形成相关的性能降低与Li 0.5 FeBO 3相固有的不良性能有关，而不是与不同相之间存在界面有关。
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