共查询到19条相似文献,搜索用时 62 毫秒
1.
微晶石墨存在加工性能差、低首效的缺点,对此采用了高温石墨化、碳化包覆对微晶石墨进行改性,引入了超高分子羧甲基纤维素钠(CMC)作为分散剂。与改性前的微晶石墨对比,加工性能和电化学性能得到大幅度提升。利用激光粒度分布仪等表征了其物理性能,利用SEM等分析了微晶石墨的结构和表面形貌,利用浆料粘度的变化表征其加工性能,并通过扣电测试了其电化学性能。结果表明:高温处理后的微晶石墨扣电首效由64.2%提升至87.1%,克容量发挥275.2 mAh/g提升至343.3 mAh/g;包覆后的微晶石墨浆料稳定性更好,克容量发挥达到394 mAh/g;使用超高分子CMC保证浆料稳定性的同时,也改善电池的倍率性能。 相似文献
2.
3.
针对微晶石墨振实密度低和首次库仑效率低的缺点,采用真空浸渍-炭化工艺对微晶石墨进行沥青炭包覆改性,利用XRD、拉曼光谱和SEM等分析了炭包覆前后微晶石墨的结构和表面形貌,利用比表面测试仪测试了样品的BET比表面积,利用振实密度仪测定振实密度,并通过恒电流充放电和循环伏安等测试了样品的电化学性能。结果表明,炭包覆后微晶石墨的石墨化度略有降低,拉曼R值由0.63增大至0.85;颗粒表面更光滑平整,BET比表面积降低0.9m2/g,振实密度从0.95g/cm3提高至1.08g/cm3;不可逆容量损失从121mAh/g减小到44mAh/g,可逆容量从300mAh/g提高到320mAh/g,首次库仑效率从71.2%提高到87.4%,而且循环性能得到明显改善。 相似文献
4.
5.
6.
7.
针对微晶石墨振实密度低和首次库仑效率低的缺点,采用真空浸渍-炭化工艺对微晶石墨进行沥青炭包覆改性,利用XRD、Raman光谱和SEM等分析了炭包覆前后微晶石墨的结构和表面形貌,利用比表面测试仪测试了样品的BET比表面积,利用振实密度仪测定振实密度,并通过恒电流充放电和循环伏安等测试了样品的电化学性能。结果表明,炭包覆后微晶石墨的石墨化度略有降低,拉曼R 值由0.63增大至0.85;颗 粒 表 面 更 光 滑 平 整,BET比 表 面 积 降低0.9m2/g,振实密度从0.95g/cm3提高至1.08g/cm3;不可逆容量损失从121mAh/g减小到44mAh/g,可逆容量从300mAh/g提高到320mAh/g,首次库仑效率从71.2%提高到87.4%,而且循环性能得到明显改善。 相似文献
8.
为了提高隐晶质石墨的固定碳含量,扩大隐晶质石墨的应用范围,采用湖南郴州地区的隐晶质石墨为原料,用氟化铵-盐酸法对其进行纯化处理。研究了氟化铵的用量、反应温度、液固比以及反应次数对隐晶质石墨固定碳含量的影响,确定了氟化铵-盐酸法提纯隐晶质石墨的最佳工艺条件。结果表明:在氟化铵的含量为45%,液固比为3∶1,恒温70℃反应2h,重复5次的条件下能够将隐晶质石墨的固定碳含量从83.08%提高到99.47%。研究表明氟化铵-盐酸法可以有效提高隐晶质石墨的固定碳含量。 相似文献
9.
10.
多晶石墨材料非等温氧化动力学及其氧化机理的研究 总被引:1,自引:0,他引:1
通过热重分析技术用模式函数和无模式函数法研究了多晶石墨材料的非等温氧化动力学, 并利用扫描电镜观察了该材料同一表面不同氧化程度的微观结构. 研究表明, 石墨氧化过程中, 活化能(E)随着氧化程度(α)增加而变化. 氧化从石墨表面的颗粒界面开始, 在氧化初期阶段, 表面原始空隙的尺寸随氧化程度的增加几乎不变. 石墨的非等温氧化过程主要分三个阶段: 氧化前期(α<20%), 氧化主要由碳氧化学反应控制; 氧化中期(20%<α<60%), 氧化为化学反应和气体扩散共同控制; 氧化后期(α>60%), 氧化主要由气体扩散控制. 运用无模式函数法研究石墨非等温氧化更具有可信度. 相似文献
11.
1. Introduction High temperature oxidation resistanceof alloys depends on the formation of adense oxide scale with slow growing rateon its top surface. The α-Al_2O_3 films appearto be the oxide with the lowest growingrate. In the CoCrAl systems, the continuousα-Al_2O_3 can not be formed if the contentof aluminium in the alloy is less than severalhundredths. For the improvement ofoxidation resistance of MCrAl (M=Co,Ni and Fe), many studies have been conducted 相似文献
12.
13.
介绍了天然石墨资源及我国石墨资源的开采现状,着重综述了几种精细加工后的石墨产品及其在一些领域中的应用,并对其发展形势做出展望。 相似文献
14.
15.
The formation mechanism of chunky graphite has been reviewed and studied. The study consisted of a unidirectional solidification method, a small droplet method and a furnace cooling method. Four kinds of iron samples were prepared, namely, the pure Fe-C, Fe-C-S, Fe-C-Ce and Fe-C-Si-Ce alloys, and three kinds of nickel samples, namely the Ni-C, Ni-C-S and Ni-C-Mg alloys. The results of the unidirectional solidification of the Ni-C alloys showed that spheroidal graphite is not observed in the continuous solidified region, in which only flake-like graphite is observed, while spheroidal graphite is usually observed in the quenched liquid region. The existence of spheroidal graphite in the solidified phase is recognized only in the discontinuous growth mode of the Ni-C-Mg alloy solidified at 150 mm/h. This means that the spheroidal graphite is directly crystallized from the melt and entrapped by the flake-like chunky graphite that is formed by the continuous growth mode. In the small droplet method, a small piece of the Fe-C or Fe-C-Ce sample was melted on a pure graphite plate then cooled at a different cooling rate in a He-3%H2 atmosphere. The graphite in the Fe-C-Ce alloy is usually spherical. Nevertheless, the graphite morphology of the final solidified area changed from spherical to chunky and chunky to ledeburite with an increase in the cooling rate. This means that the chunky graphite is formed in the residual liquid region by the solidification into Fe-graphite system. The sample was cooled in a furnace, and the graphite morphology changes from spherical to chunky and chunky to ledeburite with the decrease in the Si content. These phenomena can be confirmed by the cooling curves of these samples. 相似文献
16.
17.
18.