Center for Electrochemical Energy Storage , Skolkovo Institute of Science and Technology , 143026 Moscow , Russia.
ACS Appl Mater Interfaces. 2019 Feb 6;11(5):5084-5094. doi: 10.1021/acsami.8b19592. Epub 2019 Jan 28.
We have synthesized a library of perovskite oxides with the composition LaSr BO ( x = 0-1; B = Fe, Mn, Co) to systematically study anion-based pseudocapacitance. The electrochemical capacitance of these materials was evaluated by cyclic voltammetry and galvanostatic charging/discharging in 1 M KOH. We find that greater oxygen vacancy content (δ) upon systematic incorporation of Sr linearly increases the surface-normalized capacity with a slope controlled by the B-site element. LaSrMnO exhibited the highest specific capacitance of 492 F g at 5 mV s relative to the Fe and Co oxides. In addition, the first all-perovskite asymmetric pseudocapacitor has been successfully constructed and characterized in neutral and alkaline aqueous electrolytes. We demonstrate that the asymmetric pseudocapacitor cell voltage can be increased by widening the difference between the B-site transition metal redox potentials in each electrode resulting in a maximum voltage window of 2.0 V in 1 M KOH. Among the three pairs of asymmetric pseudocapacitors constructed from SrCoO, LaSrMnO, and brownmillerite (BM)-SrFeO, the BM-SrFeO//SrCoO combination performed the best with a high energy density of 31 Wh kg at 450 W kg and power density of 10 000 W kg at 28 Wh kg.
我们合成了一组钙钛矿氧化物，其组成式为 LaSrBO（x=0-1；B=Fe、Mn、Co），旨在系统地研究基于阴离子的赝电容。通过在 1 M KOH 中进行循环伏安法和恒电流充放电来评估这些材料的电化学电容。我们发现，随着 Sr 的系统掺入，氧空位含量（δ）的增加会使表面归一化容量呈线性增加，斜率由 B 位元素控制。LaSrMnO 在 5 mV s 下的比电容最高，为 492 F g，相对于 Fe 和 Co 氧化物。此外，我们成功地在中性和碱性水溶液电解质中构建并表征了首个全钙钛矿型不对称赝电容器。我们证明，通过扩大每个电极中 B 位过渡金属氧化还原电位之间的差异，可以增加不对称赝电容器的单元电压，从而在 1 M KOH 中实现最大 2.0 V 的电压窗口。在由 SrCoO、LaSrMnO 和 brownmillerite（BM）-SrFeO 构建的三个不对称赝电容器对中，BM-SrFeO//SrCoO 组合的性能最佳，在 450 W kg 的功率密度下能量密度为 31 Wh kg，在 28 Wh kg 的功率密度下为 10 000 W kg。
