中间相炭微球乳化-聚合法制备及电化学性能

doi:10.16085/j.issn.1000-6613.2021-1217

摘要/Abstract

摘要：

以石油基各向同性沥青为原料，采用乳化-聚合法制备出一种球形规整、粒径分布较窄的中间相沥青基微球（MPMB-et）。经过预氧化、炭化得到中间相炭微球熟球（MCMB-et），采用扫描电镜（SEM）、高分辨透射电镜（HRTEM）、X射线衍射（XRD）和Raman光谱等分析手段表征了MCMB-et的外部形貌和微观结构，并对微球的储锂性能进行测试，结果表明：MCMB-et具有较大的比表面积（13.35m²/g）、较宽的层间距（0.352nm）和一定的结构无序度（内部类石墨片层堆积结构排列无序），加快了锂离子在类石墨片层间及活性位点的嵌入和脱出。与直接热缩聚法（MCMB-t）和直接乳化法（MCMB-e）制备的微球相比，MCMB-et在循环性能和倍率性能方面均具有明显的优势，MCMB-et在500mA/g的电流密度下循环100圈仍能保持325.3mAh/g的比容量，并在2A/g的高电流密度下仍能保持240.0mAh/g的比容量。

关键词: 石油, 乳化-聚合法, 中间相炭微球, 显微结构, 电化学, 锂离子电池

Abstract:

A kind of mesophase pitch-based microspheres (MPMB-et) with perfect spherical shape and narrow particle size distribution were prepared by emulsion-polymerization method from petroleum-based isotropic pitch. After pre-oxidation and carbonization, the mesocarbon microbeads (MCMB-et) were obtained. The properties of MCMB-et were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), Raman spectroscopy and other analytical methods. Subsequently, the electrochemical performance of microspheres as the anode material for lithium-ion battery was tested. Results showed that MCMB-et had a large specific surface area (13.35m²/g), wide interlayer spacing (0.352nm) and moderate structural disorder degree (the orientation of carbon layers with the MCMB-et were distorted and irregular), which promoted the intercalation and extraction rate of lithium ions between the graphite-like flakes and active sites. Compared with the MCMBs prepared by the direct thermal polycondensation method (MCMB-t) and the direct emulsification method (MCMB-e), the MCMB-et prepared by the polymerization-emulsification method had obvious advantages in terms of cycle performance and rate performance. MCMB-et could still deliver a reversible capacity of 325.3mAh/g at a current density of 500mA/g for 100 cycles and maintain a specific capacity of 240.0mAh/g at a high current density of 2A/g.

Key words: petroleum, emulsion-polymerization method, mesocarbon microbeads, microstructure, electrochemistry, lithium-ion battery

中图分类号:

TQ127.1

龚鑫, 刘小冬, 温福山, 师楠, 刘东. 中间相炭微球乳化-聚合法制备及电化学性能[J]. 化工进展, 2022, 41(5): 2379-2388.

GONG Xin, LIU Xiaodong, WEN Fushan, SHI Nan, LIU Dong. Preparation and electrochemical performance of mesocarbon microbeads derived from emulsion-polymerization method[J]. Chemical Industry and Engineering Progress, 2022, 41(5): 2379-2388.

图/表 11

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元素分析（质量分数）/%				C/H	软化点/℃	残炭值（质量分数）/%	溶解性能（质量分数）/%
H	C	N	S	C/H	软化点/℃	残炭值（质量分数）/%	甲苯可溶物	甲苯不溶-吡啶可溶物	吡啶不溶物
6.14	91.3	0.22	1.53	1.24	110	45.5	80.0	9.10	10.9

元素分析（质量分数）/%				C/H	软化点/℃	残炭值（质量分数）/%	溶解性能（质量分数）/%
H	C	N	S	C/H	软化点/℃	残炭值（质量分数）/%	甲苯可溶物	甲苯不溶-吡啶可溶物	吡啶不溶物
6.14	91.3	0.22	1.53	1.24	110	45.5	80.0	9.10	10.9

样品	XRD 微晶参数				I_D/I_G	比表面积及孔容参数
样品	d₀₀₂/nm	L_c/nm	n	I_g/%	I_D/I_G	S_BET/m²·g^-1	V_t/cm³·g^-1	V_i/cm³·g^-1
MCMB-e	0.359	1.58	5.40	45.7	1.12	263.5	0.1484	0.1158
MCMB-et	0.352	1.61	5.57	50.0	1.02	13.35	0.1268	0.005670
MCMB-t	0.349	1.79	6.12	52.6	0.991	2.102	0.0253	0.0003624

样品	XRD 微晶参数				I_D/I_G	比表面积及孔容参数
样品	d₀₀₂/nm	L_c/nm	n	I_g/%	I_D/I_G	S_BET/m²·g^-1	V_t/cm³·g^-1	V_i/cm³·g^-1
MCMB-e	0.359	1.58	5.40	45.7	1.12	263.5	0.1484	0.1158
MCMB-et	0.352	1.61	5.57	50.0	1.02	13.35	0.1268	0.005670
MCMB-t	0.349	1.79	6.12	52.6	0.991	2.102	0.0253	0.0003624

样品	R_SEI/Ω	R_ct/Ω	σ/Ω·s^-1/2	D_Li / cm²·s^-1
MCMB-e	19.64	156	1378.3	9.87×10^-16
MCMB-et	11.1	91.0	988.2	1.92×10^-15
MCMB-t	26.21	274	1434.4	9.19×10^-16