高含量磷/硫共掺杂碳网络的制备及储钾性能的研究

The Preparation of High Content Phosphorus/Sulfur Co-Doped Carbon Network and Its Application in Potassium Ion Battery

摘要:

为了解决掺杂碳材料中磷含量低的问题，以红磷为模板和磷源，采用等离子体增强化学气相沉积法一步合成高含量磷/硫（P/S）共掺杂碳网络材料（PSCN），并将其应用于钾离子电池。实验结果表明，P/S高含量（质量分数为31.11%）PSCN为碗状的碳网络结构，其具有碳间距大、缺陷程度高、比表面积大、微孔丰富和热稳定性好等特点。将PSCN作为钾离子电池负极时，在电流密度100 mA?g^-1下可逆容量达到557.1 mAh?g^-1，在电流密度5 A?g^-1下可逆放电容量为140.3 mAh?g^-1，经1 000圈循环后容量仍有137.4 mAh?g^-1，容量保持率为69.5%，表现出优异的倍率和循环性能。而磷掺杂碳材料（PC），在电流密度100 mA?g^-1下的可逆容量为457.3 mAh?g^-1，在5 A?g^-1下经1 000圈循环后容量仅有62.8 mAh?g^-1，容量保持率较差为43.4%。PSCN的碗状结构有利于电解液的浸润，而其中的细小纤维可以很大程度地抑制K⁺在嵌入/脱嵌过程中所引起的体积膨胀，从而有效地提升了钾离子电池的倍率和循环性能。此外，高含量P/S共掺杂还可以增加PSCN的活性位点，促进储钾动力学和提高离子传输能力，进而有效提升倍率性能、赝电容占比和K⁺的扩散系数，降低反应电阻。本研究为发展钾离子电池负极材料的制备工艺提供了参考，起到理论支持作用。

Abstract:

To address the issue of low phosphorus content in doped carbon materials， red phosphorus was utilized as both a template and a phosphorus source. Through a one-step synthesis using plasma-enhanced chemical vapor deposition， a high-content phosphorus/sulfur co-doped carbon network （PSCN） was synthesized and applied to potassium-ion batteries. Experimental results indicated that the carbon/phosphorus/sulfur mixed plasma co-deposition process enabled the preparation of a carbon material with a high content of phosphorus/sulfur doping （31.11 wt%）. The obtained material exhibited a bowl-shaped carbon network structure. Due to the co-doping of phosphorus and sulfur， PSCN demonstrated characteristics such as large carbon spacing， high defect levels， large specific surface area， abundant micropores， and good thermal stability. When PSCN was utilized as the anode material for potassium-ion batteries， at a current density of 100 mA?g^-1， the reversible capacity reached 557.1 mAh?g^-1. Even at a current density of 5 A?g^-1， the reversible discharge capacity was 140.3 mAh?g^-1， and after 1 000 cycles， the capacity remained at 137.4 mAh?g^-1， representing a capacity retention rate of 69.5%. This exhibited excellent rate and cycling performance. In contrast， the reversible capacity of phosphorus-doped carbon material （PC） at a current density of 100 mA?g^-1 was 457.3 mAh?g^-1， and after 1 000 cycles at 5 A?g^-1， the capacity was only 62.8 mAh?g^-1 with a poor capacity retention rate （43.4%）. The bowl-shaped structure of this material facilitated electrolyte infiltration， while the fine fibers within the carbon network significantly suppressed the volume expansion caused by the K⁺ insertion/deinsertion process， thereby effectively enhancing the rate and cycling performance of potassium-ion batteries. Additionally， the high content of phosphorus/sulfur co-doping increased the active sites of the carbon material， promoting potassium storage kinetics and ion transport capabilities， thereby effectively enhancing rate performance， pseudo-capacitance ratio， and K⁺ diffusion coefficient， reducing reaction resistance. The high-content phosphorus/sulfur co-doped carbon network can provide a reference for the development of preparation processes for anode materials for potassium-ion batteries， offering theoretical support.