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Using Nanoscale Domain Size To Control Charge Storage Kinetics in Pseudocapacitive Nanoporous LiMn2O4 Powders
ACS Energy Letters ( IF 22.0 ) Pub Date : 2017-09-12 00:00:00 , DOI: 10.1021/acsenergylett.7b00634
Benjamin K. Lesel 1 , John B. Cook 1 , Yan Yan 1 , Terri C. Lin 1 , Sarah H. Tolbert 1, 2, 3
Affiliation  

Pseudocapacitive materials can produce charge storage devices that have both high energy and power density. Although many pseudocapacitive anode materials have been identified, there is a lack of equivalently fast charging cathode materials necessary to create full-cell devices. Recently, thin-film studies from our group have identified nanoporous LiMn2O4 with ∼15 nm domains as a pseudocapacitive cathode material. In this work, we use this insight to create nanoporous LiMn2O4 powders that can be used in practical, slurry-type thick electrode systems. Using these materials, we specifically examine the role of crystalline domain size in controlling charge storage kinetics. Four nanoporous LiMn2O4 powders were synthesized with crystallite sizes of 10, 20, 40, and 70 nm, and their charge/discharge kinetics were studied. Smaller crystallite sizes showed lower capacity but faster charge/discharge speeds, longer cycle life, and higher capacitive contribution based on kinetic analysis, whereas larger crystallite sizes showed the opposite trend. Importantly, there appeared to be a critical size above which the charge/discharge kinetics and cycle life deteriorated significantly; materials with domain sizes just below this critical size showed the best combination of electrochemical performance characteristics.

中文翻译:

使用纳米级域大小来控制伪电容性纳米多孔LiMn 2 O 4粉末中的电荷存储动力学。

伪电容材料可以产生既具有高能量密度又具有功率密度的电荷存储设备。尽管已识别出许多伪电容阳极材料,但缺少创建全电池设备所需的等效快速充电阴极材料。最近,我们小组的薄膜研究已经确定了具有约15 nm畴的纳米多孔LiMn 2 O 4作为假电容阴极材料。在这项工作中,我们利用这一见识创建了纳米多孔LiMn 2 O 4粉末,该粉末可用于实际的浆料型厚电极系统。使用这些材料,我们专门检查了晶畴尺寸在控制电荷存储动力学中的作用。四个纳米多孔LiMn 2 O 4合成了具有10、20、40和70 nm的微晶尺寸的粉末,并研究了它们的充电/放电动力学。根据动力学分析,较小的晶粒显示较低的容量,但充电/放电速度较快,循环寿命较长,并且电容贡献较大,而较大的晶粒显示相反的趋势。重要的是,似乎存在一个临界尺寸,在该尺寸以上,充电/放电动力学和循环寿命显着降低;具有小于该临界尺寸的畴尺寸的材料显示出电化学性能特征的最佳组合。
更新日期:2017-09-12
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