Copper-substituted Na0.67Ni0.3−xCuxMn0.7O2 cathode materials for sodium-ion batteries with suppressed P2–O2 phase transition
Copper-substituted Na0.67Ni0.3−xCuxMn0.7O2 cathode materials for sodium-ion batteries with suppressed P2–O2 phase transition
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DOI：
10.1039/c7ta00880e
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发表时间：
2017-05
影响因子：
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通讯作者：
L. Wang;Yong-Gang Sun;Lin-Lin Hu-Lin;Junyu Piao;Jingnan Guo;A. Manthiram;Jianmin Ma;A. Cao
中科院分区：
文献类型：
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作者：
L. Wang;Yong-Gang Sun;Lin-Lin Hu-Lin;Junyu Piao;Jingnan Guo;A. Manthiram;Jianmin Ma;A. Cao
P2型钠层状氧化物NaxMO 2（M =过渡金属）因其结构已知、上级电化学性能优异、易于合成而被认为是一种很有前途的钠离子电池正极材料。Ni 2 +/Ni 3+和Ni 3 +/Ni 4+氧化还原反应赋予P2-Na 2/3 Ni 1/3 Mn 2/3 O2电极相对高的工作电压和高的比容量。然而，从P2到O2的相变和Na+/空位有序化使得P2-Na 2/3 Ni 1/3 Mn 2/3 O2容易受到严重的电压和容量衰减。在本文中，我们提出使用电化学活性铜（II）作为独特的取代基来稳定P2相，形成Na0.67Ni0.3-xCuxMn0.7O2（x = 0，0.1，0.2和0.3）。我们的工作突出了Cu（II）在高性能正极材料结构工程中的重要性，其存在不仅可以稳定P2相，防止臭名昭著的相变，而且还有助于由于高电位Cu 2 +/Cu 3+氧化还原而产生的可充电容量。我们发现，配制为P2型Na0.67Ni0.1Cu0.2Mn0.7O2的阴极显示出良好的电池性能，同时大大减轻了结构退化。
P2-type sodium layered oxides NaxMO2 (M = transition metal) are considered as one kind of promising cathode material for sodium-ion batteries because of their known structures, superior electrochemical properties, and their ease of synthesis. The Ni2+/Ni3+ and Ni3+/Ni4+ redox reactions endow the P2–Na2/3Ni1/3Mn2/3O2 electrode with a relatively high operating voltage and high specific capacity. However, the phase transition from P2 to O2 and Na+/vacancy ordering make P2–Na2/3Ni1/3Mn2/3O2 susceptible to severe voltage and capacity decay. Herein, we propose to employ the electrochemically active copper(II) as a unique substituent to stabilize the P2 phase, forming Na0.67Ni0.3−xCuxMn0.7O2 (x = 0, 0.1, 0.2 and 0.3). Our work highlights the importance of Cu(II) in the structural engineering of high performance cathode materials, whose existence can not only stabilize the P2 phase against the notorious phase transition, but also contribute to the rechargeable capacity due to the high potential Cu2+/Cu3+ redox. We identified that the cathode formulated as P2-type Na0.67Ni0.1Cu0.2Mn0.7O2 shows favorable battery performance with much-alleviated structural degradation.