Mapping polaronic states and lithiation gradients in individual V2O5 nanowires.
Mapping polaronic states and lithiation gradients in individual V2O5 nanowires.
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DOI：
10.1038/ncomms12022
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发表时间：
2016-06-28
影响因子：
16.6
通讯作者：
Banerjee S
中科院分区：
文献类型：
--
作者：
De Jesus LR;Horrocks GA;Liang Y;Parija A;Jaye C;Wangoh L;Wang J;Fischer DA;Piper LF;Prendergast D;Banerjee S
Li离子从阴极材料的快速插入和提取对于Li离子电池的功能是必不可少的。在许多阴极材料如LiCoO 2中，锂化通过固溶体形成进行，而在其他材料如LiFePO 4中，锂化/脱锂伴随着富锂相和贫锂相之间的相变。我们表明，使用扫描透射X射线显微镜（STXM），在个别纳米线的层状V2 O 5，锂离子插层上观察到的锂化梯度产生的电子本地化和局部结构极化。V2 O 5框架上的电子与局部结构畸变耦合，产生小极化子，作为进一步Li离子插入的瓶颈。这种极化子的稳定化阻碍了纳米线上电荷密度的平衡，并产生了独特的畴。这种材料在纳米结构上的充电/放电速率的增强可以归因于规避了来自极化子形成的电荷传输的挑战。 锂离子从阴极材料中的快速插入和提取对于锂离子电池功能来说是必要的。在这里，作者提出了证据的不均匀性，电荷本地化，局部结构扭曲和极化子形成锂化后，使用扫描透射X射线显微镜。
The rapid insertion and extraction of Li ions from a cathode material is imperative for the functioning of a Li-ion battery. In many cathode materials such as LiCoO2, lithiation proceeds through solid-solution formation, whereas in other materials such as LiFePO4 lithiation/delithiation is accompanied by a phase transition between Li-rich and Li-poor phases. We demonstrate using scanning transmission X-ray microscopy (STXM) that in individual nanowires of layered V2O5, lithiation gradients observed on Li-ion intercalation arise from electron localization and local structural polarization. Electrons localized on the V2O5 framework couple to local structural distortions, giving rise to small polarons that serves as a bottleneck for further Li-ion insertion. The stabilization of this polaron impedes equilibration of charge density across the nanowire and gives rise to distinctive domains. The enhancement in charge/discharge rates for this material on nanostructuring can be attributed to circumventing challenges with charge transport from polaron formation. Rapid insertion and extraction of lithium ions from a cathode material is imperative for lithium-ion battery function. Here, the authors present evidence of inhomogeneities in charge localization, local structural distortions and polaron formation induced upon lithiation using scanning transmission X-ray microscopy.