Department of Physics and Astronomy, Uppsala University, Box 516, SE-751 20, Uppsala, Sweden.
Phys Chem Chem Phys. 2011 Dec 7;13(45):20215-22. doi: 10.1039/c1cp20673g. Epub 2011 Oct 10.
We present a study of the charge-state behavior of the Li-ion battery cathode materials Li(x)MnPO(4) and Li(x)Mn(0.9)Fe(0.1)PO(4) using X-ray absorption spectroscopy (XAS) and resonant inelastic X-ray scattering (RIXS). A set of six identical battery cathodes for each material have been cycled and left in different charge states in the range of x = 0.2…1.0 before disassembly in an Ar glove box. Unexpectedly, we find that the Mn 3d-bands are almost inert to the delithiation process, suggesting that Mn ions participate to a very small extent in the charge compensation process. In Li(x)Mn(0.9)Fe(0.1)PO(4) the Fe 3d-band shows much more response to delithiation than the Mn 3d-band. The O 2p-band hybridizes with the bands of the other ions in Li(x)MnPO(4) and Li(x)Mn(0.9)Fe(0.1)PO(4) and thus, indirectly, carries useful information about the effects of delithiation at all ion sites. We conclude that the redox reactions during lithiation/delithiation of these materials are complex and involve repopulation of charges for all constituent elements.
我们使用 X 射线吸收光谱（XAS）和共振非弹性 X 射线散射（RIXS）研究了锂离子电池正极材料 Li(x)MnPO(4)和 Li(x)Mn(0.9)Fe(0.1)PO(4)的荷电态行为。对于每种材料，我们都制备了六组相同的电池正极，这些电池正极在 Ar 手套箱中拆卸之前，在 x = 0.2…1.0 的范围内经历了不同的充电状态的循环。出乎意料的是，我们发现 Mn 3d 带几乎对脱锂过程不敏感，这表明 Mn 离子在电荷补偿过程中只参与了很小的一部分。在 Li(x)Mn(0.9)Fe(0.1)PO(4)中，Fe 3d 带对脱锂的响应比 Mn 3d 带大得多。O 2p 带与 Li(x)MnPO(4)和 Li(x)Mn(0.9)Fe(0.1)PO(4)中其他离子的带发生杂化，因此间接地提供了关于所有离子位脱锂影响的有用信息。我们得出结论，这些材料在锂化/脱锂过程中的氧化还原反应是复杂的，涉及所有组成元素的电荷再分配。
