Janus Solid-Liquid Interface Enabling Ultrahigh Charging and Discharging Rate for Advanced Lithium-Ion Batteries.
Janus Solid-Liquid Interface Enabling Ultrahigh Charging and Discharging Rate for Advanced Lithium-Ion Batteries.
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DOI：
10.1021/acs.nanolett.5b02379
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发表时间：
2015-08
期刊：
影响因子：
10.8
通讯作者：
Jiaxin Zheng;Yuyang Hou;Y. Duan;Xiaohe Song;Yi Wei;Tongchao Liu;Jiangtao Hu;H. Guo;Zengqing Zhuo-Z
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文献类型：
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作者：
Jiaxin Zheng;Yuyang Hou;Y. Duan;Xiaohe Song;Yi Wei;Tongchao Liu;Jiangtao Hu;H. Guo;Zengqing Zhuo-Z
磷酸铁锂因其高储能容量而被认为是最有前途的电池正极材料之一。同时，尽管已经对锂离子电池中的界面化学进行了广泛的研究，但1-3在原子水平上对LiFePO 4/电解质的固液界面知之甚少。在此，我们报道了在水性电解质中由纳米LiFePO 4颗粒组成的电池阴极，其具有600 C的高充电和放电速率（3600/600 = 6 s充电时间，1 C = 170 mAh g（-1）），达到72 mAh g（-1）能量存储（理论容量的42%）。相比之下，在有机电解液中，200 C时的可及容量急剧下降至20 mAh g（-1）.对LiFePO 4-H2O和LiFePO 4-EC进行了全面的电化学测试和从头算计算，（碳酸亚乙酯）系统中，我们确定了在LiFePO 4-H2O系统中Janus水合界面的瞬时形成，其中固体LiFePO 4表面的截断对称性由化学吸附的H2O分子补偿，形成半固体（LiFePO 4）和半液体（H2O）的两亲配位环境，其简化了表面附近的Li去溶剂化过程，这使得快速Li离子穿过固/液界面成为可能。
LiFePO4 has long been held as one of the most promising battery cathode for its high energy storage capacity. Meanwhile, although extensive studies have been conducted on the interfacial chemistries in Li-ion batteries,1-3 little is known on the atomic level about the solid-liquid interface of LiFePO4/electrolyte. Here, we report battery cathode consisted with nanosized LiFePO4 particles in aqueous electrolyte with an high charging and discharging rate of 600 C (3600/600 = 6 s charge time, 1 C = 170 mAh g(-1)) reaching 72 mAh g(-1) energy storage (42% of the theoretical capacity). By contrast, the accessible capacity sharply decreases to 20 mAh g(-1) at 200 C in organic electrolyte. After a comprehensive electrochemistry tests and ab initio calculations of the LiFePO4-H2O and LiFePO4-EC (ethylene carbonate) systems, we identified the transient formation of a Janus hydrated interface in the LiFePO4-H2O system, where the truncated symmetry of solid LiFePO4 surface is compensated by the chemisorbed H2O molecules, forming a half-solid (LiFePO4) and half-liquid (H2O) amphiphilic coordination environment that eases the Li desolvation process near the surface, which makes a fast Li-ion transport across the solid/liquid interfaces possible.