Graphitic carbon balanced between high plateau capacity and high rate capability for lithium ion capacitors
Graphitic carbon balanced between high plateau capacity and high rate capability for lithium ion capacitors
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DOI：
10.1039/c7ta03862c
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发表时间：
2017-07
影响因子：
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通讯作者：
Yang Zhewei;Huajun Guo;Xinhai Li;Zhixing Wang;Jiexi Wang;Yansen Wang;Yan Zhiliang;Dongcai Zhang-Dongcai-Zh
中科院分区：
文献类型：
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作者：
Yang Zhewei;Huajun Guo;Xinhai Li;Zhixing Wang;Jiexi Wang;Yansen Wang;Yan Zhiliang;Dongcai Zhang-Dongcai-Zh
以剑麻纤维为原料，在低温（<1200℃）下经预碳化和催化石墨化制备石墨炭（GC）。高原容量受气相色谱有序度的调节。制备的GC1100在1100℃下具有高平台容量，在0.2 V以下为243 mA h g−1，占0.05 a g−1时总可逆容量354ma h g−1的68%，具有高倍率容量（1 a g−1时222ma h g−1）和良好的循环稳定性。石墨结构和非晶结构的共存是其优异的电化学性能的主要原因。石墨结构有助于提高平台容量和导电性，非晶结构为Li+离子提供了更方便的通道，并保护石墨结构免受电解质的腐蚀。另外，以剑麻纤维活性炭（sfac2）为正极，GC1100为负极组装锂离子电容器（LIC）。在143和6628 W kg - 1条件下，LIC的能量密度分别为104和32 W h kg - 1，并且具有良好的循环稳定性，在0.5 A g - 1条件下，循环3000次后能量密度保持率为94.7%，在1 A g - 1条件下保持率为96.5%。
Graphitic carbon (GC) derived from sisal fibers is prepared through pre-carbonization and catalytic graphitization at low temperature (<1200 °C). The plateau capacity is regulated by the ordered degree of GC. The as-prepared GC1100 at 1100 °C possesses a high plateau capacity of 243 mA h g−1 below 0.2 V representing 68% of the total reversible capacity of 354 mA h g−1 at 0.05 A g−1, high rate capability (222 mA h g−1 at 1 A g−1) and excellent cycling stability. The superior electrochemical performance is ascribed to the coexistence of graphitic structure and amorphous structure. The graphitic structure contributes to high plateau capacity and electrical conductivity, and the amorphous structure supplies a more convenient pathway for Li+ ions and protects the graphitic structure from the etching of the electrolyte. Additionally, a lithium ion capacitor (LIC) is assembled with sisal fiber activated carbon (SFAC-2) as the positive electrode and GC1100 as the negative electrode. The LIC displays high energy densities of 104 and 32 W h kg−1 obtained at 143 and 6628 W kg−1, respectively, and outstanding cycling stability with the energy density retention of 94.7% at 0.5 A g−1 and 96.5% at 1 A g−1 after 3000 cycles.