物理化学学报2022，Vol.38Issue(2)：95-103,9.DOI:10.3866/PKU.WHXB202012062
石墨烯包覆天然球形石墨作为锂离子电池的负极材料,是否需要乙炔黑导电剂?
Is there a Demand of Conducting Agent of Acetylene Black for Graphene-Wrapped Natural Spherical Graphite as Anode Material for Lithium-Ion Batteries?
摘要
Abstract
Graphene-wrapped natural spherical graphite (G/SG)composites were prepared using the encapsulation-carbonization approach.The morphology and structure of the composites were characterized by scanning electron microscopy and X-ray diffraction analysis.The electrochemical performance of the composites with different graphene contents as anode materials for lithium-ion batteries was investigated by various electrochemical techniques.In the absence of acetylene black (AB),the G/SG composites were found to exhibit high specific capacity with high first-cycle coulombic efficiency,good cycling stability,and high rate performance.Compared with the natural spherical graphite (SG) electrode,the G/SG composite electrode with 1％ graphene exhibited higher reversible capacity after 50 cycles;this capacity performance was equal to that of the SG + 10％AB electrode.Moreover,when the addition of 2.5％ graphene,the composite electrode exhibited higher initial charge capacity and reversible capacity during 50 cycles than the SG+10％AB electrode.The significant improvement of the electrochemical performance of the G/SG composite electrodes could be attributed to graphene wrapping.The graphene shell enhances the structural integrity of the natural SG particles during the lithiation and delithiation processes,further improving the cycling stability of the composites.Moreover,the bridging of adjacent SG particles allows the formation of a highly conductive network for electron transfer among SG particles.Graphene in the composites serves as not only an active material but also a conductive agent and promotes the improvement of electrochemical performance.When 5％AB was added,the reversible capacity of the 5％G/SG electrodes significantly increased from 381.1 to 404.5 mAh·g-1 after 50 cycles at a rate of 50 mA·g-1 and from 82.5 to 101.9 mAh·g-1 at 1 A·g-1,suggesting that AB addition improves the performance of the G/SG composite electrodes.AB particles connect to G/SG particles through point contact type and fill the gaps between G/SG.A more effective conductive network is synergistically formed via graphene-AB connection.Although graphene wrapping and AB addition improve the performance of natural graphite electrodes,such as through increase in electrical conductivity and enhancement of Li-storage performance,including improvement of reversible capacity,rate performance,and cycling stability,electrode density typically decreases with graphene or AB addition,which should consider the balance between the gravimetric and volumetric capacities of graphite anode materials in practical applications.These results have great significance for expanding the commercial application scope of natural graphite.Our work provides new understanding and insight into the electrochemical behavior of natural SG electrodes in lithium-ion batteries and is helpful for the fabrication of high-performance anode materials.关键词
石墨烯/石墨烯包覆/天然球形石墨/锂离子电池/负极材料/导电剂/乙炔黑Key words
Graphene/Graphene-wrapped/Natural spherical graphite/Lithium-ion battery/Anode material/Conductive agent/Acetylene black分类
化学化工引用本文复制引用
刘学伟,牛莹,曹瑞雄,陈晓红,商红岩,宋怀河..石墨烯包覆天然球形石墨作为锂离子电池的负极材料,是否需要乙炔黑导电剂?[J].物理化学学报,2022,38(2):95-103,9.基金项目
The project was supported by the National Natural Science Foundation of China (U1610252,51911530126).国家自然科学基金(U1610252,51911530126)资助项目 （U1610252,51911530126）
