There is growing interest in developing sodium based energy storage devices as alternatives to Li for large-scale energy storage. We report a highly stable hybrid system comprising a sodium metal anode, a highly porous N/S co-doped mesoporous carbon cathode and the non-flammable ionic liquid electrolyte N-propyl-N-methyl pyrrolidinium bis(fluorosulfonyl) imide (C₃mpyrFSI). This hybrid device operates at 100% coulombic efficiency and shows almost complete capacity retention over 3000 cycles. Owing to the reversible cathode reactions between Na⁺ and N/S functionalities on the carbon surface, a very high capacity of 716 mA h g⁻¹ (at a rate of C/16) was achieved between 3.8 V and 0.005 V vs. Na⁺/Na. An optimised device could provide energy density as high as 263 W h kg⁻¹. At high rate, the devices achieved power density of 1463 W kg⁻¹. These metrics increase to 270 W h kg⁻¹ and 3822 W kg⁻¹ at 50 °C, highlighting the excellent combination of a supercapacitor-type cathode with a sodium metal anode and an ionic liquid electrolyte for large-scale energy storage.

中文翻译：

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离子液体型钠金属混合超级电容器电池†

开发钠基储能装置作为锂用于大规模储能的替代方案的兴趣日益浓厚。我们报告了一个高度稳定的混合系统，该系统包括钠金属阳极，高度多孔的N / S共掺杂中孔碳阴极和不易燃的离子液体电解质N-丙基-N-甲基吡咯烷鎓双（氟磺酰基）酰亚胺（C ₃ mpyrFSI ）。该混合设备以100％的库仑效率运行，并在3000个循环中显示出几乎完全的容量保持能力。由于碳表面上的Na ⁺和N / S官能团之间可逆的阴极反应，在3.8 V至0.005 V vs. 5 V之间实现了716 mA hg ^-1的极高容量（以C / 16的速率）。Na ⁺ / Na。优化的设备可以提供高达263 W h kg ^-1的能量密度。在高速率下，这些设备实现了1463 W kg ^-1的功率密度。这些指标在50°C时分别增加到270 W h kg ^-1和3822 W kg ^-1，突显了超级电容器型阴极与钠金属阳极和离子液体电解质的完美结合，可进行大规模的能量存储。