Energy storage is an integral part of the modern world. One of the newest and most interesting concepts is the internal hybridization achieved in metal-ion capacitors. In this study, for the first time we used sodium borohydride (NaBH 4 ) as a sacrificial material for the preparation of next-generation sodium-ion capacitors (NICs). NaBH 4 is a material with large irreversible capacity of ca. 700 mA h g −1 at very low extraction potential close to 2.4 vs Na + /Na 0 . An assembled NIC cell with the composite-positive electrode (activated carbon/NaBH 4 ) and hard carbon as the negative one operates in the voltage range from 2.2 to 3.8 V for 5,000 cycles and retains 92% of its initial capacitance. The presented NIC has good efficiency >98% and energy density of ca. 18 W h kg −1 at power 2 kW kg −1 which is more than the energy (7 W h kg −1 at 2 kW kg −1 ) of an electrical double-layer capacitor (EDLC) operating at voltage 2.7 V with the equivalent components as in NIC. Tin phosphide (Sn 4 P 3 ) as a negative electrode allowed the reaching of higher values of the specific energy density 33 W h kg −1 (ca. four times higher than EDLC) at the power density of 2 kW kg −1 , with only 1% of capacity loss upon 5,000 cycles and efficiency >99%.

中文翻译：

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硼氢化钠（NaBH4）作为下一代钠离子电容器的高容量材料

储能是现代世界不可或缺的一部分。最新和最有趣的概念之一是在金属离子电容器中实现的内部杂交。在这项研究中，我们首次使用硼氢化钠（NaBH 4）作为牺牲材料，用于制备下一代钠离子电容器（NIC）。NaBH 4是一种具有约ca的不可逆容量的材料。700 mA h g -1在极低的萃取电位下，相对于Na + / Na 0接近2.4。具有复合正极（活性碳/ NaBH 4）和作为负极的硬碳的组装NIC电池在2.2至3.8 V的电压范围内运行5,000个循环，并保留其初始电容的92％。所提供的NIC的效率> 98％，能量密度约为ca。功率为2 kW kg -1时为18 W h kg -1，大于以2.7 V电压工作的双电层电容器（EDLC）的能量（在2 kW kg -1时为7 W h kg -1）。 NIC中的等效组件。磷化锡（Sn 4 P 3）作为负极可在2 kW kg -1的功率密度下达到更高的比能密度33 W h kg -1（约为EDLC的四倍）。 5,000次循环时只有1％的容量损失，效率> 99％。