磷化铁复合材料的制备及其作为锂离子电池负极材料性能研究

Preparation and Properties of Iron Phosphide Composites as Anode Materials for Lithium Ion Batteries

摘要: 开发高比电容和良好的循环稳定性的新型锂离子电池负极材料是开发新能源材料重点之一。在本工作中，使用植酸作为磷和碳源，利用沉淀法简单合成含有植酸和钴的前驱体，进一步高温退火合成FeP_x/C。同时，在原材料中掺杂石墨烯合成FeP_x/C@C材料，用作高性能的LIB负极材料。采用XRD、SEM、TEM、Raman和XPS等表征了复合材料的形貌结构及化学组成。此外，还通过电化学方法，包括循环伏安法(CV)、恒电流充放电测试(GCD)对制备的复合材料进行电化学性能分析，结果分析显示，FeP_x/C和FeP_x/C@C复合材料在100 mA∙g⁻¹的电流密度下初始比容量可以达到637和818.3 mAh∙g⁻¹。在相同电流密度下循环40次后，比容量分别为192.2和253.8 mAh∙g⁻¹；随后进行200次循环后，剩余169.5和190.9 mAh∙g⁻¹的比容量，从40圈到200圈的衰减率分别为88.2%和75.3%，这表明了锂离子的快速嵌入和脱嵌的优良电化学性能。磷掺杂的碳材料改善了导电性并减轻了在充电–放电过程中FeP_x的体积变化，保持了结构完整性。基于这些优点，FeP_x/C@C和FeP_x/C复合材料作为LIB负极材料展现出高比电容和良好的循环性能，具有良好的商业应用前景。

Abstract: The development of new lithium-ion battery anode materials with high specific capacitance and remarkable cycle stability is one of the key points in exploration of new energy materials. In this work, phytic acid was used as the phosphorus and carbon source, and the precursor containing phytic acid and cobalt was simply synthesized by precipitation method, and FeP_x/C was further synthesized by high temperature annealing. At the same time, the raw material was doped with graphene to synthesize FeP_x/C@C material, which was used as a high performance LIB anode ma-terial. The morphology and chemical composition of the composites were characterized by XRD, SEM, TEM, Raman, and XPS. In addition, the electrochemical properties of the prepared composites were analyzed by electrochemical methods, including cyclic voltammetry (CV) and constant current charge and discharge tests (GCD). The results showed that FeP_x/C and FeP_x/C@C composites have an initial specific capacity of 637 and 818.3 mAh∙g⁻¹ at a current density of 100 mA∙g⁻¹. After 40 cycles at the same current density, the specific capacities were 192.2 and 253.8 mAh∙g⁻¹, respectively. After cycling 200 cycles at the same current density, the capacity of 169.5 and 190.9 mAh∙g⁻¹ remained, the decay rate from 40 to 200 cycles being 88.2% and 75.3%, indicating excellent electrochemical performance for rapid lithium ion insertion/extraction cycles. The phospho-rus-doped carbon material improves electrical conductivity and reduces the volume change of FeP_x during charge-discharge to maintain structural integrity. Based on these advantages, FeP_x/C and FeP_x/C@C composites exhibit high specific capacitance and remarkable cycle performance as LIB anode materials, and have promising commercial application prospects.