Hard carbon is synthesized by heat-treating macroporous phenolic resin at different temperatures. We study influences of temperature on the structures and electrode properties of the hard carbon in Na and K cells. X-ray diffraction and scattering data of the samples confirm the decreased interlayer distance between sp²-carbon sheets and the expanded internal pores at the raised temperatures from 1100 to 1500 °C. Reversible capacities in Na cells increase with an increase in the heat-treatment temperature. Hard carbon carbonized at 1500 °C delivers the largest capacities of 386 and 336 mAh g^–1 at 10 mA g^–1 in Na and K cells, respectively.

中文翻译：

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用大孔酚醛树脂合成的高容量硬碳钠离子和钾离子电池

硬碳是通过在不同温度下对大孔酚醛树脂进行热处理而合成的。我们研究温度对Na和K细胞中硬碳的结构和电极性能的影响。样品的X射线衍射和散射数据证实，在1100至1500°C的升高温度下，sp ^2-碳片与膨胀的内部孔之间的层间距离减小。Na电池中的可逆容量随着热处理温度的升高而增加。在1500°C下碳化的硬碳在Na和K电池中的最大电流分别为10 mA g ^–1时，最大容量为386和336 mAh g ^–1。