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Jingchun Sun, Jindiao Guan, Suqing Zhou, Jiewei Ouyang, Nan Zhou, Chunxia Ding, and Mei’e Zhong, Improving the electrocatalytic activity of Fe, N co-doped biochar for polysulfide by regulation of N–C and Fe–N–C electronic configurations, Int. J. Miner. Metall. Mater., 30(2023), No. 12, pp.2421-2431. https://dx.doi.org/10.1007/s12613-023-2683-9
Jingchun Sun, Jindiao Guan, Suqing Zhou, Jiewei Ouyang, Nan Zhou, Chunxia Ding, and Mei’e Zhong, Improving the electrocatalytic activity of Fe, N co-doped biochar for polysulfide by regulation of N–C and Fe–N–C electronic configurations, Int. J. Miner. Metall. Mater., 30(2023), No. 12, pp.2421-2431. https://dx.doi.org/10.1007/s12613-023-2683-9
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调控N–C和Fe–N–C的电子结构增强Fe, N共掺杂生物炭对多硫化物的电催化活性

摘要: 将农业剩余生物质转化为生物炭作为锂硫电池的硫宿主材料,是缓解温室效应和实现废弃物资源化利用的一种很有前景的方法。在锂硫电池充放电过程中,如何抑制中间产物多硫化物的穿梭效应,加速活性物质硫与多硫化物的相互转化,是开发长寿命、高面积容量锂硫电池的关键问题。然而,原始生物炭的导电性低,电催化位点有限,难以实现大规模应用。本文通过芝麻壳和乙二胺四乙酸铁钠(NaFeEDTA)共热解制备铁氮共掺杂生物炭(Fe–NOPC)来解决这些问题。在合成过程中,利用NaFeEDTA作为额外的碳源来调节氮掺杂的化学环境,从而提高石墨氮、吡咯氮、吡啶氮和Fe–Nx键的含量。当将Fe–NOPC作为硫宿主时,其表面的吡啶氮和吡咯氮会调节生物炭的表面电子结构,加速电子/离子的传递,而正电性的石墨氮可以通过静电作用吸附固定硫相关物种。Fe–Nx键能够与中间产物多硫化锂形成较强的Li–N和S–Fe键,促进多硫化锂的氧化还原反应。利用这些优点,所制的Fe–NOPC /S复合阴极在面载量为3.8 mg·cm−2、电流密度为0.1C时,获得4.45 mAh·cm−2的高面积容量;1C时仍保持为3.45 mAh·cm−2。可见,本文所制Fe–NOPC材料在实现高能量锂硫电池方面具有巨大的潜力。

 

Improving the electrocatalytic activity of Fe, N co-doped biochar for polysulfide by regulation of N–C and Fe–N–C electronic configurations

Abstract: The conversion of agricultural residual biomass into biochar as a sulfur host material for Li–S batteries is a promising approach to alleviate the greenhouse effect and realize waste resource reutilization. However, the large-scale application of pristine biochar is hindered by its low electrical conductivity and limited electrocatalytic sites. This paper addressed these challenges via the construction of Fe–N co-doped biochar (Fe–NOPC) through the copyrolysis of sesame seeds shell and ferric sodium ethylenediaminetetraacetic acid (NaFeEDTA). During the synthesis process, NaFeEDTA was used as an extra carbon resource to regulate the chemical environment of N doping, which resulted in the production of high contents of graphitic, pyridinic, and pyrrolic N and Fe–Nx bonds. When the resulting Fe–NOPC was used as a sulfur host, the pyridinic and pyrrolic N would adjust the surface electron structure of biochar to accelerate the electron/ion transport, and the electropositive graphitic N could be combined with sulfur-related species via electrostatic attraction. Fe–Nx could also promote the redox reaction of lithium polysulfides due to the strong Li–N and S–Fe bonds. Benefiting from these advantages, the resultant Fe–NOPC/S cathode with a sulfur loading of 3.8 mg·cm−2 delivered an areal capacity of 4.45 mAh·cm−2 at 0.1C and retained a capacity of 3.45 mAh·cm−2 at 1C. Thus, this cathode material holds enormous potential for achieving energy-dense Li–S batteries.

 

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