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Na+/Vacancy Disordered P2-Na0.67Co1–xTixO2: High-Energy and High-Power Cathode Materials for Sodium Ion Batteries
ACS Applied Materials & Interfaces ( IF 8.3 ) Pub Date : 2018-01-19 00:00:00 , DOI: 10.1021/acsami.7b16077
Seok Mun Kang 1, 2 , Jae-Hyuk Park 1, 2 , Aihua Jin 1, 2 , Young Hwa Jung 3 , Junyoung Mun 4 , Yung-Eun Sung 1, 2
Affiliation  

Although sodium ion batteries (NIBs) have gained wide interest, their poor energy density poses a serious challenge for their practical applications. Therefore, high-energy-density cathode materials are required for NIBs to enable the utilization of a large amount of reversible Na ions. This study presents a P2-type Na0.67Co1–xTixO2 (x < 0.2) cathode with an extended potential range higher than 4.4 V to present a high specific capacity of 166 mAh g–1. A group of P2-type cathodes containing various amounts of Ti is prepared using a facile synthetic method. These cathodes show different behaviors of the Na+/vacancy ordering. Na0.67CoO2 suffers severe capacity loss at high voltages due to irreversible structure changes causing serious polarization, while the Ti-substituted cathodes have long credible cycleability as well as high energy. In particular, Na0.67Co0.90Ti0.10O2 exhibits excellent capacity retention (115 mAh g–1) even after 100 cycles, whereas Na0.67CoO2 exhibits negligible capacity retention (<10 mAh g–1) at 4.5 V cutoff conditions. Na0.67Co0.90Ti0.10O2 also exhibits outstanding rate capabilities of 108 mAh g–1 at a current density of 1000 mA g–1 (7.4 C). Increased sodium diffusion kinetics from mitigated Na+/vacancy ordering, which allows high Na+ utilization, are investigated to find in detail the mechanism of the improvement by combining systematic analyses comprising TEM, in situ XRD, and electrochemical methods.

中文翻译:

Na + /空位无序P2-Na 0.67 Co 1– x Ti x O 2:用于钠离子电池的高能和高功率阴极材料

尽管钠离子电池(NIB)引起了广泛的兴趣,但其差的能量密度对其实际应用提出了严峻的挑战。因此,NIB需要高能量密度的阴极材料,以能够利用大量可逆的Na离子。这项研究提出了一种P2型Na 0.67 Co 1– x Ti x O 2x <0.2)阴极,其扩展电位范围高于4.4 V,具有166 mAh g –1的高比容量。使用简便的合成方法制备一组含各种量Ti的P2型阴极。这些阴极显示出Na + /空位有序的不同行为。钠0.67由于不可逆的结构变化导致严重的极化,CoO 2在高电压下会遭受严重的容量损失,而Ti取代的阴极具有长期可靠的循环能力以及高能量。特别是,即使经过100次循环,Na 0.67 Co 0.90 Ti 0.10 O 2仍具有出色的容量保持能力(115 mAh g –1),而Na 0.67 CoO 2在4.5 V截止条件下仍具有可忽略的容量保持力(<10 mAh g –1)。Na 0.67 Co 0.90 Ti 0.10 O 2还具有出色的108 mAh g倍率能力–1在1000 mA g - 1的电流密度下(7.4 C)。研究了减少的Na + /空位排序增加的钠扩散动力学,从而提高了Na +的利用率,通过结合包括TEM,原位XRD和电化学方法在内的系统分析,详细研究了改善机理。
更新日期:2018-01-19
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