Journal Article

Azo compounds as a family of organic electrode materials for alkali-ion batteries

Jiang, Jianjun, Wang, Chunsheng, Chen, Ji, Hou, Singyuk, Deng, Tao, Ji, Xiao, Gaskell, Karen J., Luo, Chao, Fan, Xiulin, Borodin, Oleg, Wang, Ruixing

2018

Overview

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.

• Publisher: National Academy of Sciences
• Subject: Azo compounds / Batteries / Chemistry / Current density / Decay rate / Density functional theory / Electrochemical analysis / Electrochemistry / Electrode materials / Electrodes / Lithium / Lithium-ion batteries / Metal ions / Organic chemicals / Organic compounds / Physical Sciences / Reaction mechanisms / Rechargeable batteries