Engineering semicoherent interface with O–Fe–Se coordination for boosting the capacity and rate capability of a battery-type supercapacitor anode

Abstract

The low capacity and rate capability of the battery-type supercapacitor anode prevent its widespread application. In this paper, we construct a semicoherent heterojunction of Fe₂O₃/FeSe₂ as an advanced battery-type supercapacitor anode to overcome the bottleneck. A series of characterization and first-principles calculations confirm that the special heterointerface manipulation automatically generates a stronger inherent electric field, thereby enhancing the electron transport rate and the OH⁻ adsorption capacity. In addition, it facilitates additional redox reactions between the active materials and OH⁻ and makes the reaction system easier to execute. Taking advantage of these benefits, the prepared anode has a high specific capacity of 199.2 mA h g⁻¹ (1 A g⁻¹) and retains 90.2% of its initial capacity after 5000 cycles at 105.8 mA h g⁻¹ (10 A g⁻¹). In addition, an asymmetric supercapacitor device is fabricated with the prepared Fe₂O₃/FeSe₂ as the anode, which provides a maximum energy density of 52.55 W h kg⁻¹ at 0.8 kW kg⁻¹ and a capacity retention of 91.2% even after 15,000 cycles. In our work, a novel strategy for the optimal design of a battery-type supercapacitor anode with a large capacity and superior rate capability is conceived, significantly advancing the widespread application of transition metal compounds in energy storage systems.

摘要

低容量和低倍率限制了电池型超级电容阳极材料的大规模应用.本文通过构建一种具有半共格异质界面特性的Fe₂O₃/FeSe 2 纳米结构作为先进的阳极材料来解决这一瓶颈. 系列表征和第一性原理计算表明,这种特殊的异质界面不仅能自发产生较强的内建电场, 从而提高电子传递速率和OH⁻离子的吸附能力; 还可使得活性物质与OH⁻之间发生更多的氧化还原反应, 并且使该反应体系更容易进行. 基于上述优势,所制备出的阳极材料的最大比容量为199.2 mA h g⁻¹(1 A g⁻¹), 并且在10 A g⁻¹下仍能保持105.8 mA h g⁻¹, 同时, 经历5000次循环后, 其比容量可维持初始值的90.2%. 此外, 以Fe₂O₃/FeSe₂作为阳极组装的非对称超级电容器在0.8 kW kg⁻¹时的能量密度为52.55 W h kg⁻¹, 即使经历15,000次循环, 该器件还能维持初始容量的91.2%. 我们的工作为设计大容量和高倍率性能的电池型超级电容器阳极材料提供了一种创新性的策略, 有望推动过渡金属化合物在储能系统中的大规模应用.