CAJ | 학술논문

使用草酸盐共沉淀法合成了LiNi_(0.5)Mn_(0.5)O_2,并研究了共沉淀时的pH条件对终产物的结构、形貌及电化学性能的影响.采用X射线衍射(XRD)和扫描电镜(SEM)表征了在pH值为4.0、5.5、7.0和8.5时得到的共沉淀和终产物LiNi_(0.5)Mn_(0.5)O_2的结构和形貌.使用充放电实验研究了不同pH条件下得到的LiNi_(0.5)Mn_(0.5)O_2的电化学性能.结果表明,pH为7.0时,合成的材料颗粒更小、分布最均匀,材料具有良好的层状特征,且材料中锂镍的混排程度最小.电化学测试结果印证了pH为7.0时合成的材料具有更好的电化学性能,在0.1C的倍率下,材料的首次放电比容最达到了185 mAh·g~(-1),在循环20周后,放电比容量仍然保持在160 mAh·g~(-1).X射线光电子能谱(XPS)测试结果表明,pH为7.0时合成的LiNi_(0.5)Mn_(0.5)O_2中Ni为+2价,Mn为+4价.
사용초산염공침정법합성료LiNi_(0.5)Mn_(0.5)O_2,병연구료공침정시적pH조건대종산물적결구、형모급전화학성능적영향.채용X사선연사(XRD)화소묘전경(SEM)표정료재pH치위4.0、5.5、7.0화8.5시득도적공침정화종산물LiNi_(0.5)Mn_(0.5)O_2적결구화형모.사용충방전실험연구료불동pH조건하득도적LiNi_(0.5)Mn_(0.5)O_2적전화학성능.결과표명,pH위7.0시,합성적재료과립경소、분포최균균,재료구유량호적층상특정,차재료중리얼적혼배정도최소.전화학측시결과인증료pH위7.0시합성적재료구유경호적전화학성능,재0.1C적배솔하,재료적수차방전비용최체도료185 mAh·g~(-1),재순배20주후,방전비용량잉연보지재160 mAh·g~(-1).X사선광전자능보(XPS)측시결과표명,pH위7.0시합성적LiNi_(0.5)Mn_(0.5)O_2중Ni위+2개,Mn위+4개.
The oxalate co-precipitation method was used to synthesize LiNi_(0.5)Mn_(0.5)O_2.The effects of pH on the structure,morphology,and electrochemical performance of LiNi_(0.5)Mn_(0.5)O_2 were investigated.The crystal structures and surface morphologies of the oxalate precursor and LiNi_(0.5)Mn_(0.5)O_2 obtained at pH=4.0,5.5,7.0,8.5 were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM) methods.The electrochemical performance of LiNi_(0.5)Mn_(0.5)O_2 was evaluated by galvanostatic charge/discharge tests.Results show that the LiNi_(0.5)Mn_(0.5)O_2 obtained at pH=7.0 has a smaller particle size,more uniform distribution,better layered characteristics and a smaller degree of carlon mixing.Electrochemical tests confirmed that the sample obtained at pH=7.0 had the best electrochemical performance.At 0.1 C rate.itsdischarge capacity reached 185 mAh·g~(-1) at the first cycle and remained over 160 mAh·g~(-1) after the 20th cycle.X-ray photoelectron spectroscopy (XPS) results indicated that the oxidation states of Ni and Mn in the LiNi_(0.5)Mn_(0.5)O_2 obtained at pH=7.0 were +2 and +4.respectively.