<p>Aqueous Zn | |I<sub>2</sub> batteries, involving I<sup>-</sup>/I<sup>0</sup>/I<sup>+</sup> redox, are promising yet usually facing low I<sub>2</sub> utilization dominated by I<sup>0</sup>/I<sup>+</sup> redox, especially under high loadings. Unlocking alternative pathway to I<sup>0</sup>/I<sup>+</sup> redox, preferably in noncorrosive dilute electrolytes, is a crucial solution. Here, we report a pathway towards more thermodynamically favorable I<sup>0</sup>/I<sup>+</sup> redox, via a unique carbon-halogen bond substitution. This pathway is realized with a low-concentrated (0.7 M), noncorrosive organohalide additive (2-bromoacetamide, BrAce), triggering a reversible Br-C···I<sup>(0)</sup> and C-I<sup>(+)</sup>-Br bond substitution. Compared with conventional interhalogen bonding (I-Br) pathway, this pathway synchronously lowers the barrier for I⁰/I⁺ redox and strengthens the anti-hydrolysis of I<sup>+</sup> species, by elaborately regulating axial δ hole activity of interhalogen bond (I<sup>(δ+)</sup>-Br). Notably, this pathway enables sustainable operation of four-electron Zn | |I<sub>2</sub> batteries with high I<sub>2</sub> loading (8.6 ~ 24.0 mg cm<sup>-2</sup>), featuring improved performances: (1) high I<sub>2</sub> utilizations (55% ~ 80%) at high rates (5.8 ~ 46.4 mA cm<sup>-2</sup>), (2) long lifespan (<InlineEquation ID="IEq1"> <EquationSource Format="TEX">\( &gt; \)</EquationSource> <EquationSource Format="MATHML"><math> <mo>&gt;</mo> </math></EquationSource> </InlineEquation>400 cycles) with practical areal capacity ( ~ 3.85 mA h cm<sup>-2</sup>) and 99.5% retention even at 47.5 mA cm<sup>-2</sup>. This pathway opens an exciting research direction to unlock unusual halogen chemistry for scalable, high-energy, sustainable aqueous batteries.</p>

错误:搜索内容不能为空,请输入英文关键词
错误:关键词超出字数限制,请精简
高级检索

Carbon-halogen bond substitution enables high-utilization four-electron iodine redox in noncorrosive dilute electrolytes

  • Zhiheng Shi,
  • Yongchao Tang,
  • Yue Wei,
  • Guigui Liu,
  • Haolong Huang,
  • Jintu Qi,
  • Zhenfeng Feng,
  • Minghui Ye,
  • Yufei Zhang,
  • Zhipeng Wen,
  • Xiaoqing Liu,
  • Qi Yang,
  • Chunyi Zhi,
  • Cheng Chao Li

摘要

Aqueous Zn | |I2 batteries, involving I-/I0/I+ redox, are promising yet usually facing low I2 utilization dominated by I0/I+ redox, especially under high loadings. Unlocking alternative pathway to I0/I+ redox, preferably in noncorrosive dilute electrolytes, is a crucial solution. Here, we report a pathway towards more thermodynamically favorable I0/I+ redox, via a unique carbon-halogen bond substitution. This pathway is realized with a low-concentrated (0.7 M), noncorrosive organohalide additive (2-bromoacetamide, BrAce), triggering a reversible Br-C···I(0) and C-I(+)-Br bond substitution. Compared with conventional interhalogen bonding (I-Br) pathway, this pathway synchronously lowers the barrier for I⁰/I⁺ redox and strengthens the anti-hydrolysis of I+ species, by elaborately regulating axial δ hole activity of interhalogen bond (I(δ+)-Br). Notably, this pathway enables sustainable operation of four-electron Zn | |I2 batteries with high I2 loading (8.6 ~ 24.0 mg cm-2), featuring improved performances: (1) high I2 utilizations (55% ~ 80%) at high rates (5.8 ~ 46.4 mA cm-2), (2) long lifespan ( \( > \) > 400 cycles) with practical areal capacity ( ~ 3.85 mA h cm-2) and 99.5% retention even at 47.5 mA cm-2. This pathway opens an exciting research direction to unlock unusual halogen chemistry for scalable, high-energy, sustainable aqueous batteries.