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Metal–Organic Framework-Derived Nanoconfinements of CoF2 and Mixed-Conducting Wiring for High-Performance Metal Fluoride-Lithium Battery
ACS Nano ( IF 15.8 ) Pub Date : 2020-12-24 , DOI: 10.1021/acsnano.0c08918
Feixiang Wu 1 , Vesna Srot 2 , Shuangqiang Chen 3 , Mingyu Zhang 4 , Peter A. van Aken 2 , Yong Wang 3 , Joachim Maier 2 , Yan Yu 5, 6
Affiliation  

Metal fluoride (MF) conversion cathodes theoretically show higher gravimetric and volumetric capacities than Ni- or Co-based intercalation oxide cathodes, which makes metal fluoride–lithium batteries promising candidates for next-generation high-energy-density batteries. However, their high-energy characteristics are clouded by low-capacity utilization, large voltage hysteresis, and poor cycling stability of transition MF cathodes. A variety of reasons is responsible for this: poor reaction kinetics, low conductivities, unstable MF/electrolyte interfaces and dissolution of active species upon cycling. Herein, we combine the synthesis of the metal–organic-framework (MOF) with the low-temperature fluorination to prepare MOF-shaped CoF2@C nanocomposites that exhibit confinement of the CoF2 nanoparticles and efficient mixed-conducting wiring in the produced architecture. The ultrasmall CoF2 nanoparticles (5–20 nm on average) are uniformly covered by graphitic carbon walls and embedded in the porous carbon framework. Within the CoF2@C nanocomposite, the cross-linked carbon wall and interconnected nanopores serve as electron- and ion-conducting pathways, respectively, enabling a highly reversible conversion reaction of CoF2. As a result, the produced CoF2@C composite cathodes successfully restrain the above-mentioned challenges and demonstrate high-capacity utilization of ∼500 mAh g–1 at 0.2C, good rate capability (up to 2C), and long-term cycle stability over 400 cycles. Overall, the presented study not only reports on a simple composite design to achieve high-energy characteristics in CoF2–Li batteries but also may provide a general solution for many other metal fluoride–lithium batteries.

中文翻译:

高性能金属氟化物-锂电池的CoF 2的金属-有机骨架衍生的纳米约束和混合导电布线

从理论上讲,金属氟化物(MF)转换阴极比镍或钴基插层氧化物阴极具有更高的重量和体积容量,这使金属氟化物-锂电池成为下一代高能量密度电池的有希望的候选者。然而,它们的高能量特性由于低容量利用率,大的电压滞后以及过渡MF阴极的较差的循环稳定性而变得模糊。造成这种情况的原因多种多样:反应动力学差,电导率低,MF /电解质界面不稳定以及循环时活性物质溶解。在本文中,我们将金属-有机骨架(MOF)的合成与低温氟化反应相结合,以制备表现出CoF 2限制作用的MOF形CoF 2 @C纳米复合材料纳米粒子和高效的混合导电布线。CoF 2超小纳米颗粒(平均5-20 nm)被石墨碳壁均匀覆盖,并嵌入多孔碳骨架中。在CoF 2 @C纳米复合材料中,交联的碳壁和相互连接的纳米孔分别充当电子和离子传导途径,从而实现了CoF 2的高度可逆转化反应。结果,所生产的CoF 2 @C复合阴极成功地克服了上述挑战,并证明了约500 mAh g –1的高容量利用率在0.2C的温度下具有良好的倍率能力(最高2C),并且在400次循环中具有长期循环稳定性。总体而言,本研究报告不仅报告了一种简单的复合设计以实现CoF 2 -Li电池的高能特性,而且还可以为许多其他金属氟化物-锂电池提供通用解决方案。
更新日期:2021-01-26
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