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arXiv 2408.01595cond-mat.mtrl-sci
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低钴P2型钠离子电池正极材料中改善的界面电阻与晶体结构稳定性

Improved interfacial resistance and crystal-structure stability in a low-cobalt P2-type sodium-ion battery cathode material

William Rexhausen, Christian Parsons, Uma Garg, Deyang Qu, Prasenjit Guptasarma

AI总结:

本文研究低钴P2型钠离子电池正极NMFCO,通过阻抗等效电路建模与恒电流斜率分析,证明其结构稳定、界面电阻低且能量密度高。

摘要:

我们描述了Na0.67Mn0.625Fe0.25Co0.125O2(NMFCO),一种P2型钠离子电池正极。与早期研究相比,我们的成分含钴量显著更低,在1.5至4.3 V范围内表现出接近190 mAhg-1的放电容量和超过500 mWhg-1的比能量密度。该材料相较同类材料还表现出改善的结构稳定性。在原始相(P63/mmc、P63(OP4)或正交Cmcm)与所谓Z相之间发生的此类变化,是Na0.67Mn0.65Fe0.35O2(NMFO)等其他P2型正极的固有问题。我们提出两种阻抗谱等效电路模型,以理解采用钠金属负极的电池中的电化学过程。我们的等效电路建模结合对初始恒电流斜率的分析,揭示了固体电解质界面处的极化和界面电荷转移电阻显著降低。我们揭示,晶体结构稳定性、更低内阻、较高比能量密度以及改善的电池健康状况的综合效应,使这种低钴P2型正极成分成为新型钠离子电池极具前景的候选材料。

英文摘要:

We describe Na0.67Mn0.625Fe0.25Co0.125O2 (NMFCO), a P2-type sodium-ion battery cathode. Our composition, with significantly less Co than in an earlier study, shows discharge capacity close to 190 mAhg-1 and specific energy density exceeding 500 mWhg-1 in the 1.5 to 4.3 V range. The material also shows an improved structural stability over similar materials. Such changes, between the pristine phase (P63/mmc, P63 (OP4), or orthorhombic Cmcm) and the so-called Z phase, are endemic to other P2-type cathodes such as Na0.67Mn0.65Fe0.35O2 (NMFO). We propose two equivalent circuit models of impedance spectroscopy to understand electrochemical processes in our cells with a sodium metal anode. Our equivalent circuit modeling, combined with an analysis of the initial galvanostatic slope, reveals a significant reduction in the polarization and interfacial charge-transfer resistance at the solid electrolyte interface. We reveal that the combined effects of crystal structure stability, lower internal resistance, relatively high specific energy density, and improved battery health make this low-cobalt P2-type cathode composition a very promising candidate for new sodium-ion batteries.

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