Sodium ions pre-intercalation stabilized tunnel structure of Na2Mn8O16 nanorods for supercapacitors with long cycle life
Sodium ions pre-intercalation stabilized tunnel structure of Na2Mn8O16 nanorods for supercapacitors with long cycle life
复制标题
用于长循环寿命超级电容器的钠离子预嵌入稳定Na2Mn8O16纳米棒隧道结构
DOI：
10.1016/j.cej.2018.08.033
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发表时间：
2018-12-15
影响因子：
15.1
通讯作者：
Hu, Chenguo
中科院分区：
文献类型：
--
作者：
Xu, Weina;Wan, Jing;Hu, Chenguo
具有离子预嵌入结构的晶体具有有利于电解质离子嵌入/脱嵌且结构变形较小的优点。然而，在长时间循环中的电容损失在一些离子预嵌入材料中仍然是一个问题。为了提高超级电容器的循环寿命，需要具有快速氧化还原反应和高稳定性的新型电极材料，并且需要了解充放电过程中晶体中的离子扩散行为。本文报道了一种新型的超级电容器电极材料--钠离子预插层隧道结构的纳米棒Na 2 Mn 8 O 16。在Li 2SO 4、Na 2SO 4和K2 SO 4水溶液电解质中，Na 2 Mn 8 O 16电极在1A/g的电流密度下分别达到744.8、738.2和667.5F/g的电容，并且在10，000次循环后，它们也显示出较长的循环寿命，电容保持率分别为93.5%、96.1%和91.1%。采用密度泛函理论计算方法研究了Na 2 Mn 8 O 16隧道结构中的原子尺度离子扩散行为。实验和理论研究共同揭示了氧化还原反应和隧道结构中的离子嵌入都有助于在各种中性硫酸盐电解质中的高电容和长循环寿命。此外，基于Na 2 Mn 8 O 16电极的对称全固态柔性超级电容器展示了在电化学能量存储中的实际应用。
A crystal with ion pre-intercalation structure has advantage that benefits electrolyte ion intercalation/deintercalation and less deformation in structure. However, the capacitance loss in long time cycles is still a problem in some ion pre-intercalation materials. To improve cycle lifetime of supercapacitor, new electrode materials with fast redox reactions and high stability are highly desired, and the ion diffusion behaviors in the crystal during the charge/discharge process should be understand. Herein, we report a new type electrode material, Na2Mn8O16 nanorods with Na ion pre-intercalation in tunnel structure, which exhibits excellent performance for supercapacitor. The Na2Mn8O16 electrode achieves capacitance 744.8, 738.2 and 667.5 F/g under the current density of 1 A/g in Li2SO4, Na2SO4 and K2SO4 aqueous electrolytes, respectively, which also show long cycle life with 93.5%, 96.1% and 91.1% capacitance retention after 10,000 cycles. Atomic-scale ion diffusion behaviors in the tunnel-structure of Na2Mn8O16 are studied by the density functional theory calculation. The experimental and theoretical investigations together unveil that both redox reaction and ion intercalation in tunnel structure contribute to the high capacitance and long cycle life in various neutral sulfate electrolytes. In addition, symmetric all-solid-state flexible supercapacitors based on the Na2Mn8O16 electrodes demonstrate practical applications in electrochemical energy storage.