Department of Materials Science and Engineering, South University of Science and Technology of China, Shenzhen 518055, China.
Nat Commun. 2016 Nov 7;7:13318. doi: 10.1038/ncomms13318.
It is a challenge to prepare organic electrodes for sodium-ion batteries with long cycle life and high capacity. The highly reactive radical intermediates generated during the sodiation/desodiation process could be a critical issue because of undesired side reactions. Here we present durable electrodes with a stabilized α-C radical intermediate. Through the resonance effect as well as steric effects, the excessive reactivity of the unpaired electron is successfully suppressed, thus developing an electrode with stable cycling for over 2,000 cycles with 96.8% capacity retention. In addition, the α-radical demonstrates reversible transformation between three states: C=C; α-C·radical; and α-C anion. Such transformation provides additional Na storage equal to more than 0.83 Na insertion per α-C radical for the electrodes. The strategy of intermediate radical stabilization could be enlightening in the design of organic electrodes with enhanced cycling life and energy storage capability.
制备具有长循环寿命和高容量的钠离子电池有机电极是一项挑战。由于不希望的副反应，在钠化/脱钠过程中产生的高反应性自由基中间体可能是一个关键问题。在这里，我们提出了具有稳定的 α-C 自由基中间体的耐用电极。通过共振效应和空间位阻效应，成功抑制了未成对电子的过度反应性，从而开发出一种具有稳定循环的电极，可在 2000 次循环以上保持 96.8%的容量保持率。此外，α-自由基在三种状态之间表现出可逆转化：C=C；α-C·自由基；和α-C 阴离子。这种转化为电极提供了额外的钠储存，相当于每个α-C 自由基超过 0.83 个 Na 插入。中间自由基稳定化策略在设计具有增强循环寿命和储能能力的有机电极方面具有启发性。
