摘要
采用表面掺杂包覆改性的方法对LiMn2O4尖晶石型锂离子电池正极材料进行改性.以Al为表面掺杂元素,Al(NO3)3为原料,研究了Al3+掺杂量为7.1%(原子分数)时不同温度(300、400、500、600、700、750、800℃)下的改性效果.研究发现,随着热处理温度的升高,改性样品的最大比容量先升高后降低,在700℃达到最大值;循环衰减先增大后降低再增大;这是由于随着热处理温度的升高,包覆层逐渐分解并与LiMn2O4颗粒反应固溶,在750℃完全固溶,衰减达到极小值,而后固溶层向颗粒内部扩散,导致包覆层对颗粒免受电解液溶解的保护能力变弱,因而容量衰减增大.其中700℃热处理5h的样品最大比容量为133.6mAh·g-1,循环50周衰减3.4%.研究表明Al3+表面掺杂包覆改性有利于促进LiMn2O4尖晶石型锂离子电池正极材料的商业化生产,具有大规模应用的前景.
A doping-coating surface modification method was used to improve the cycle performance of the lithium-ion battery cathode material spinel LiMn 2 O 4.Al was chosen as the doping element and Al（NO 3） 3 as the raw material.We investigated Al 3＋ doping of 7.1%（atomic fraction）at the temperatures of 300,400,500,600,700,750,and 800℃.It was found that at increasing temperatures,the maximum specific capacity of the modified samples first increased and then decreased,with a maximum at 700℃.The fading rate increased initially with temperature as well,and then decreased,followed by a small rise with temperature.This is because the coated layer gradually reacted with the LiMn 2 O 4 granule at elevated temperatures and became a completely solid solution layer by 750℃.The fading rate reached the minimum at the same time.Subsequently,the solid solution layer diffused into the LiMn 2 O 4 granule,weakening the granule protection so that the fading rate slightly increased.Among these samples,the maximum specific capacity（133.6 mAh·g-1）was for the sample treated at 700℃ for 5 h,and the fading rate was 3.4%after 50 cycles.It is shown that doping-coating surface modification with Al 3＋ may enable the commercial application of spinel LiMn 2 O 4 cathode material for lithium-ion batteries.
出处
《物理化学学报》
SCIE
CAS
CSCD
北大核心
2012年第5期1177-1182,共6页
Acta Physico-Chimica Sinica
