Abstract:

Silicon, as one of the most promising anode materials for lithium-ion batteries, boasts a high theoretical capacity (4200mAh/g). However, silicon suffers from poor electrical conductivity and significant volume expansion during the charge-discharge process, leading to pulverization of the anode and a consequent sharp decline in battery performance. Secondary particle formation can enhance the isotropic characteristics of the material, thereby improving the initial Coulombic efficiency and enhancing rate capability. Among the factors, the size of secondary particles is critical. In this study, fulvic acid potassium (FAP) was used as a carbon source to fabricate Si/C anode secondary particles. The Si/C composite anode material was assembled into coin cells and characterized using scanning electron microscopy (SEM) and electrochemical techniques to analyze the impact of the air inlet during the spray drying process on the size of secondary particles. The results indicated that at a spray feed rate of 310mL/h and an air inlet rate of 29m³/h, the Si/C anode composite material achieved an initial Coulombic efficiency of 86.39%. After 100 cycles, the reversible capacity was significantly higher than that of pure silicon anode material, retaining a reversible capacity of 1134.1mAh/g at a 0.1A/g rate test.

Key words: electrochemistry, composites, particle size distribution, lithium-ion battery, fulvic acid potassium, secondary particle

摘要：

硅作为最有前景的锂离子电池负极材料，拥有较高的理论容量（4200mAh/g）。然而，硅的导电性较差并且在充放电过程中会发生巨大的体积膨胀，使得硅负极粉碎，导致电池性能急剧下降。二次造粒能使材料具有更好的各向同性特征，改善电池的首次库仑效率，进而提升倍率性能。其中，二次颗粒尺寸成为关键因素。本文以黄腐酸钾（FAP）为碳源制备硅/碳负极二次颗粒，将硅/碳负极复合材料组装为扣式电池，利用扫描电子显微镜（SEM）、电化学技术等表征手段对比分析了喷雾干燥过程中进风量对二次颗粒的尺寸影响。结果表明，喷雾进液速率为310mL/h、进风量为29m³/h时，制备的硅/碳负极复合材料的首次库仑效率达到86.39%，其循环100次后的可逆容量仍远高于纯硅负极材料，在0.1A/g倍率测试后仍具有1134.1mAh/g的可逆容量。

关键词: 电化学, 复合材料, 粒度分布, 锂离子电池, 黄腐酸钾, 二次颗粒