Azo compounds as a family of organic electrode materials for alkali-ion batteries
Azo compounds as a family of organic electrode materials for alkali-ion batteries
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DOI：
10.1073/pnas.1717892115
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发表时间：
2018-02-27
影响因子：
11.1
通讯作者：
Wang, Chunsheng
中科院分区：
文献类型：
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作者：
Luo, Chao;Borodin, Oleg;Wang, Chunsheng
有机化合物是可持续发展的锂离子电池的理想材料，但循环稳定性差、功率密度低限制了其规模化应用。本文报道了一类含有偶氮基(N=N)的有机化合物，用于可逆的锂/脱硫化反应。以共轭结构中心含偶氮基团的偶氮苯-4，4‘-二羧酸锂盐(ADALS)为模型偶氮化合物，研究了偶氮化合物的电化学性质和反应机理。在LiBS中，ADALS在0.5C(相当于95 mAg(-1)的电流密度)下可以提供190mAhg(-1)的容量，当电流密度增加到2C、10C和20C时，ADALS仍然保持90%、71%和56%的容量。此外，ADALS在20℃下5,000次循环后仍保持初始容量的%，容量衰减率为0.0023%/次，是所有有机化合物中性能最好的化合物之一。在钠离子电池中也观察到了ADALS优越的电化学行为，表明偶氮化合物是碱性离子电池的通用电极材料。用密度泛函理论(DFT)计算证实了偶氮化合物对碱性离子的高度可逆氧化还原反应。它为发展可持续电池提供了机会。
Organic compounds are desirable for sustainable Li-ion batteries (LIBs), but the poor cycle stability and low power density limit their large-scale application. Here we report a family of organic compounds containing azo group (N=N) for reversible lithiation/delithiation. Azobenzene-4,4'-dicarboxylic acid lithium salt (ADALS) with an azo group in the center of the conjugated structure is used as a model azo compound to investigate the electrochemical behaviors and reaction mechanism of azo compounds. In LIBs, ADALS can provide a capacity of 190 mAh g(-1) at 0.5 C (corresponding to current density of 95 mA g(-1)) and still retain 90%, 71%, and 56% of the capacity when the current density is increased to 2 C, 10 C, and 20 C, respectively. Moreover, ADALS retains 89% of initial capacity after 5,000 cycles at 20 C with a slow capacity decay rate of 0.0023% per cycle, representing one of the best performances in all organic compounds. Superior electrochemical behavior of ADALS is also observed in Na-ion batteries, demonstrating that azo compounds are universal electrode materials for alkali-ion batteries. The highly reversible redox chemistry of azo compounds to alkali ions was confirmed by density-functional theory (DFT) calculations. It provides opportunities for developing sustainable batteries.