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Morphology and Interconnected Microstructure-Driven High-Rate Capability of Li-Rich Layered Oxide Cathodes.
ACS Applied Materials & Interfaces ( IF 8.3 ) Pub Date : 2020-06-23 , DOI: 10.1021/acsami.0c05752
Vidyashree Hebbar 1 , M Viji 1 , Akshay Kumar Budumuru 1 , Sanjeev Gautam 2 , Keun Hwa Chae 3 , K Balaji 4 , N T Kalyana Sundaram 4 , A K Subramani 4 , C Sudakar 1
Affiliation  

A Li-rich layered oxide (LLO) cathode with morphology-dependent electrochemical performance with the composition Li1.23Mn0.538Ni0.117Co0.114O2 in three different microstructural forms, namely, randomly shaped particles, platelets, and nanofibers, is synthesized through the solid-state reaction (SSR-LLO), hydrothermal method (HT-LLO), and electrospinning process (ES-LLO), respectively. Even though the cathodes possess different morphologies, structurally they are identical. The elemental dispersion studies using energy-dispersive X-ray spectroscopy mapping in scanning transmission electron microscopy show uniform distribution of elements. However, SSR-LLO and ES-LLO nanofibers show slight Co-rich regions. The electrochemical studies of LLO cathodes are evaluated in terms of charging/discharging, C-rate capability, and cyclic stability performances. A high reversible capacity of 275 mA h g–1 is achieved in the fibrous LLO cathode which also demonstrates good high-rate capability (80 mA h g–1 at 10 C-rate). These capacities and rate capabilities are superior to those of SSR-LLO [210.5 mA h g–1 (0.1 C-rate) and 4 mA h g–1 (3 C-rate)] and HT-LLO [242 mA h g–1 (0.1 C-rate) and 22 mA h g–1 (10 C-rate)] cathodes. The ES-LLO cathode exhibits 88% capacity retention after 100 cycles at 1 C-rate. A decrease in voltage on cycling is found to be common in all three cathodes; however, minimal voltage decay and capacity loss are observed in ES-LLO upon cycling. Well-connected small LLO particles constituting fibrous microstructural forms in ES-LLO provide an enhanced electrolyte/cathode interfacial area and reduced diffusion path length for Li+. This, in turn, facilitates superior electrochemical performance of the electrospun Co-low LLO cathode suitable for quick charge battery applications.

中文翻译:

富锂层状氧化物阴极的形貌和互连的微结构驱动的高速能力。

具有形态依赖性的电化学性能的富Li层状氧化物(LLO)阴极,成分为Li 1.23 Mn 0.538 Ni 0.117 Co 0.114 O 2分别通过固态反应(SSR-LLO),水热法(HT-LLO)和电纺丝工艺(ES-LLO)合成三种不同的微结构形式,即无规形状的颗粒,血小板和纳米纤维。即使阴极具有不同的形态,它们在结构上也是相同的。在扫描透射电子显微镜中使用能量色散X射线光谱映射绘制的元素色散研究表明元素的均匀分布。但是,SSR-LLO和ES-LLO纳米纤维显示出少量的富含Co的区域。LLO阴极的电化学研究是根据充电/放电,C速率能力和循环稳定性能进行评估的。275 mA hg –1的高可逆容量在纤维状的LLO阴极中实现了这一点,这也显示出良好的高倍率能力(在10 C倍率下为80 mA hg –1)。这些容量和速率能力优于SSR-LLO [210.5 mA hg –1(0.1 C速率)和4 mA hg –1(3 C速率)]和HT-LLO [242 mA hg –1(0.1 C速率)和22 mA hg –1(10 C速率)]阴极。ES-LLO阴极在1 C速率的100个循环后显示88%的容量保持率。发现在所有三个阴极中,循环电压的降低都是常见的。但是,ES-LLO在循环时观察到最小的电压衰减和容量损失。良好连接的小LLO颗粒构成ES-LLO中的纤维微结构形式,可提供增强的电解质/阴极界面面积,并减小Li +的扩散路径长度。反过来,这促进了静电纺Co-low LLO阴极的优异电化学性能,适用于快速充电电池应用。
更新日期:2020-07-22
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