摘要
结合锂离子电池容量衰减主要机制,建立了基于动态参数响应的电化学热耦合模型,研究磷酸铁锂电池循环寿命及电池内部的电化学行为.模型采用恒流恒压充放电制度对电池进行循环充放电仿真计算.结果显示:800次循环后,电池容量衰减率约为6.35%,电池内部固体电解质界面膜阻抗增大了15.6 m?·m^(-2).分别探讨了充放电倍率、负极活性物质颗粒粒径、负极固相体积分数对电池循环寿命的影响.研究表明:400次循环后,相较于1C(C表示充放电倍率)倍率下的容量衰减率3.31%,2C,3C,4C容量衰减率分别达到3.93%,4.69%和5.04%;负极活性颗粒粒径为2和10μm时对应容量衰减率分别为2.89%,3.87%,差值接近1%;固相体积分数在[0.5,0.6]区间内能保持最好的电池循环稳定性和寿命发挥.
It is one of the important issues for electric vehicle to utilize power batteries which have long lifetime and excellent performance. For optimizing electrochemical performance and lifetime of the lithium ion battery, an electrochemical- thermal model based on dynamic response is developed by COMSOL MULTIPHYSICS. The modeling theory is the reaction mechanism of lithium iron phosphate battery which also includes a parasitic reaction occurring in the constant current and constant voltage charging process. The model consists of three parts： electro-chemical model, thermal model and capacity fade model. A series of temperature-dependent parameters and lithium ion concentration-dependent parameters relevant to the reaction rate and Li＋ transport are employed in this model. Comparing with the results of the experimental test, the model shows high accuracy and reliability. The capacity losses and electrochemical behaviors of the battery in cyclic processes with different rates are investigated. The results show that when the battery is cycled at a rate of 1C, the capacity fading rate is about 6.35%, meanwhile the solid electrolyte interface membrane impedance of the battery is increased by 15.6 m^t.m-2 after 800 time cycle. In the charge process, the side reaction rate within the anode shows a decreasing trend along the direction from the cooper current collector to separator, which is consistent with the lithium concentration in the anode. Besides, the effects of charge/discharge rate, negative active material particle radius and negative solid volume fraction on the battery cycle life are also discussed respectively. Compared with the fading rate of 3.31% after 400 time cycle with 1C rate, the capacity fading rates for 26＂, 3C, 4C reach to 3.93%, 4.69% and 5.04% respectively. When the average particle radii of the anode are 2 m and 10 m, corresponding capacity fading rates are 2.89% and 3.87%, showing a difference of nearly 1%. The study for solid volume fraction demonstrates that the battery with a solid volume
出处
《物理学报》
SCIE
EI
CAS
CSCD
北大核心
2017年第11期328-338,共11页
Acta Physica Sinica
基金
国家自然科学基金(批准号:51204211
51222403)
工信部工业转型升级强基工程专项(批准号:0714-EMTC02-5271/6)
湖南省战略性新兴产业与新型工业化专项资金(批准号:2015GK1045)资助的课题~~
关键词
容量衰减
充放电倍率
体积分数
颗粒半径
capacity fade, charge and discharge rate, volume fraction, particle radius
