摘要
综合利用碳-硫测试、XRD、SEM、BET、拉曼光谱、EIS及扣式电池测试等分析技术手段,对LiFePO4/C制备过程中原位包碳与非原位包碳(分别记为LFP-1、LFP-2)的研究结果表明,在碳含量、相结构一致的前提下,LFP-1为10μm左右带孔的大颗粒,LFP-2为由100nm左右小颗粒组成的类球状颗粒,前者的电荷转移电阻(Rct)、倍率性能、循环性能优于后者,这归结于不同的包碳方式导致的LiFePO4/C微观结构的不同,从而使拉曼光谱结果中LFP-1的ID/IG和Asp3/Asp2低于LFP-2,即前者石墨化程度高于后者。从而表明,碳的包裹情况对改善LiFePO4/C的电化学性能有重要的影响。该结果对提高橄榄石类锂离子电池正极材料的综合性能有重要意义。
Through comparative studying on LiFePO4/C preparation process of adding carbon source in precursor and pre-sintered material, marked as LFP-1 (in-situ carbon coating) and LFP-2 respectively, by means of C-S test, XRD, SEM, BET, Raman, the effects of carbon content, morphology, particle size and surface carbon structure on the electrochemical performance of LiFePO4/C cathodes were investigated. SEM images showed that particle sizes of LFP-I and LFP-2 are about 10μm and 100nm respectively. The EIS and galvnostatic charge- discharge tests indicated that LFP-1 has lower charge transfer resistance (R,) , better rate and cycle performance than that of LFP-2, which can be attributed to the different microstructure and the higher degree of graphitized carbon of LiFePQ/C. Raman spectroscopic analysis showed that the ratio of the I D/IG; and A ,3/A,2 of LFP-1 is lower that of LFP-2, which means the degree of graphitized carbon of LFP-1 is higher than that of LEP-2. These results have important significance for improving the overall performance of olivine cathode materials for lithium ion batteries.
出处
《化学通报》
CAS
CSCD
北大核心
2014年第6期527-533,共7页
Chemistry
基金
国家高技术研究发展计划(863计划)项目(2013AA032002)
安泰科技股份有限公司技创项目(2011JA02GYF和2013JA02PYF)资助
关键词
原位包碳
石墨化程度
电化学性能
锂离子电池
LiFePO4/C, In-situ carbon coating, Graphitization degree, Electrochemical performance, Lithiumion batteries