摘要
以微晶石墨为原料,采用改进的Hummer’s法制备氧化石墨烯(MGO)。从氧化剂用量、粒径、中温反应温度和反应时间4个方面研究微晶石墨的氧化程度,并将MGO作为原料之一制备三元导电浆料,同时考量了MGO和天然鳞片石墨制备的氧化石墨烯(FGO)三元导电剂对磷酸铁锂(LFP)电池电化学性能的影响。结果表明:当球磨24h后粒径为6.76μm的微晶石墨与高锰酸钾的质量比为1∶3时,在35℃的水浴锅中中温反应20h,即可得到氧化程度良好的MGO;与FGO相比,MGO具有更小的片径,但团聚现象相对更明显。在LFP电池中分别添加MGO和FGO基三元导电剂,当电流密度为10C时LFP//MGO和LFP//FGO的平均放电比容量为72.2mAh·g^(-1)和111.9mAh·g^(-1);在电流密度为1C时,经过100次循环后放电比容量分别为146.7mAh·g^(-1)和161.7mAh·g^(-1);在5C倍率下循环200次后容量保持率分别为78.57%和96.22%。不同的石墨烯多元导电浆料都能有效地改善电池的性能,以微晶石墨为原料的导电浆料性能还需进一步提升。
Using microcrystalline graphite as raw material,the graphene oxide(MGO)was prepared by the improved Hummer’s method.The oxidation degree of microcrystalline graphite was studied from the four aspects of oxidant dosage,particle size,medium temperature reaction temperature and reaction time.The influence of MGO as one of the raw materials on the preparation of ternary conductive slurry was also investigated.The effects of MGO and graphene oxide(FGO)prepared from natural flake graphite on the electrochemical properties of lithium phosphate(LFP)battery were studied.The results show that,when the mass ratio of microcrystalline graphite to potassium permanganate is 1∶3 after the ball grinding 24 h,the temperature reaction is 20 h at 35℃,the MGO with good oxidation level is obtained.MGO has a smaller sheet diameter than FGO,but the phenomenon of reunion is more obvious.The LFP batteries added ternary conductive agents based on MGO and FGO have the average discharge ratio of 72.2 mAh·g^(-1) and 111.9 mAh·g^(-1) respectively at 10C.The discharge capacities of LFP batteries possess 146.7 mAh·g^(-1) and 161.7 m Ah·g^(-1),respectively at 1C after 100 cycles.After 200 cycles at 5C,the capacity retention rates are 78.57%and 96.22%,respectively.Different graphene multiple conductive slurry can effectively improve the performance of the battery,and the performance of the conductive slurry made with microcrystal graphite needs to be further improved.
作者
陈惠
廖亚林
王日雷
周洋
刘洪波
Chen Hui;Liao Ya-lin;Wang Ri-lei;Zhou Yang;Liu Hong-bo(School of Materials,Hunan University,Hunan Changsha 410082,China;Hunan Advanced Carbon Materials Research Institute,Hunan Changsha 410082,China)
出处
《炭素技术》
CAS
北大核心
2022年第2期27-35,共9页
Carbon Techniques
基金
湖南省重大科技专项计划项目(2018GK1030)。
关键词
微晶石墨
石墨烯
磷酸铁锂电池
导电浆料
电化学性能
Microcrystalline graphite
graphene
phosphate lithium battery
conductive slurry
electrochemical properties
