【作者】 梅文昕； 王青松； 孙金华；

【Author】 MEI Wen-xin;WANG Qing-song;SUN Jin-hua;State Key Laboratory of Fire Science,University of Science and Technology of China;

【机构】 中国科学技术大学火灾科学国家重点实验室；

【摘要】 在锂离子电池的充放电过程中,随着电极颗粒中锂的嵌入和脱出,颗粒会发生膨胀和收缩而导致应力的产生,应力过大时会发生电极材料的脱落,破裂,致使电池内阻增加,循环性能下降,容量衰减,最终导致电池失效。本文对正负极椭球颗粒建立三维电化学-力耦合模型,计算了充电过程中电极颗粒的锂浓度分布以及负极石墨颗粒的应力分布,结果表明两个颗粒接触的部位应力较大,且过大的应力会削弱锂离子的脱嵌能力,导致两个负极颗粒接触的部位锂浓度较低而两个正极颗粒接触的部位锂浓度较高。此外,颗粒表面径向应力为零,径向应力最大值出现在颗粒中心;最大切向应力出现在两个颗粒接触的表面。更多还原

【Abstract】 During the charge-discharge process of the lithium ion battery,the electrode particles will expand or contract with the intercalation/deintercalation of the lithium,which will correspondingly generate the stress.Exceed stress will lead to the rupture and broken of the electrode materials,resulting in an increase in the battery internal resistance,causing the cycle performance and capacity degradation,and finally leading to the failure of the battery.In this paper,a three dimensional electrochemical-mechanical model is modeled for the positive and negative ellipsoid particles to obtain the lithium concentration and stress distribution of the particles.The results show that the stress is large at the connection area between the two particles,and the excessive stress will impair the intercalation/deintercalation ability of lithium ions,which cause the lower lithium concentration between the negative particles and the higher lithium concentration between the positive particles.Additionally,the radial stress is zero at the surface of the particles,while the maximum of the radial stress is located at the center of the particle,the maximum of the tangential stress occurs at the surface between the two particles.更多还原