【摘要】 随着电池循环充放电，电极颗粒膨胀收缩会导致电极颗粒表面出现裂纹甚至导致电极颗粒破裂，进一步引发电极活性材料损失和锂离子损失，加剧锂离子电池老化。为准确地表征和预测电极颗粒应变及裂纹生长过程，该文提出一种考虑电化学扩散和材料形变的锂离子电池电极颗粒裂纹生长模型。该模型根据锂离子在电极颗粒中的扩散过程计算电极颗粒固相扩散诱导应力，并根据电极颗粒所受应力预测电极颗粒裂纹生长速度。最终，所提模型实现了颗粒裂纹生长与锂离子扩散的双向耦合。实验和仿真结果表明，所提模型能准确地预测电极颗粒所受应力、颗粒裂纹生长趋势和电极活性材料损失。更多还原

【Abstract】 Loss of electrode active material in lithium-ion batteries is one of the main causes of lithium-ion battery degradation,and electrode particle rupture is in turn the main mechanism leading to electrode active material loss.However,it is difficult to directly observe the state of electrode particles during charge and discharge.Therefore,this paper proposes a fractional-order model with electrolyte considering stress （FOMeS） to observe the lithium-ion concentration and stress changes in electrode particles.Furthermore,the electrode particle cracking model is proposed based on FOMeS and the material properties of the electrode particles.The accuracy of the proposed model is indirectly verified through NCA (LiNi _0.8 Co ₀.₁₅ Al _0.05 O ₂) battery cycling aging experiments.Firstly,to achieve accurate internal state observation in lithium-ion batteries,a fractional-order model with electrolyte （FOMe） is proposed.FOMe is a simplified electrochemical lithium-ion batteries model based on single particle model,which simplifies solid-phase lithium-ion diffusion with fractional-order Padéapproximation,and simplifies electrolyte-phase lithium-ion diffusion with two state-space systems.FOMe achieves accurate lithiumion concentration prediction in solid phase and electrolyte phase with low computational complex.Secondly,the lithium-ion concentration distribution in electrode particles affects the solid-phase diffusioninduced stresses,and the strain of electrode particles affects the solid-phase lithium-ion concentration distribution.To establish the relationship between the stress,the strain and the lithium-ion concentration in electrode particles,a fractional-order model with electrolyte considering stress （FOMeS） is proposed.To verify the effectiveness of FOMeS,a NCA lithium-ion battery aging experiment is designed.The 1/30C constant current discharge voltage data is used to identify the thermodynamic parameters of NCA batteries in different aging stages with particle swarm optimization.The positive and negative electrodecapacitiesidentified from the experiment are highly consistent with the positive and negative electrode capacities predicted from FOMeS.The positive electrode capacity RMSE and MAPE of FOMeS are 0.073 9 A·h and 1.373 4%,respectively.The negative electrode capacity RMSE and MAPE of FOMeS are 0.260 2 A·h and 3.178 5%,respectively.The experiment result shows that FOMeSachieves accurate lithium-ion concentration and solid phase diffusion-induced stress prediction.Finally,to further investigate the effect of solid-phase diffusion-induced stress on the crack growth trend of electrode particles,the electrode particle cracking model is proposed.The proposed model combines the solid phase diffusion-induced stress based on FOMeS with the material properties of the electrode particles,the crack growth rate of the electrode particles can be calculated by the Paris equation.The stress and strain of electrode particles are simulated at 1C rate constant current charge and discharge.The simulation results show that the crack growth rate of electrode particles accelerates with the deepening of the crack length of electrode particles.For the NCA battery used in the experiment,the radius of negative electrode particles is larger than that of positive electrode particles,the solid-phase diffusion coefficient of negative electrode particles is smaller than that of positive electrode particles,and the Young’s modulus of negative electrode particles is smaller than that of positive electrode particles.Therefore,the growth rate of crack propagation in negative electrode particles is faster than that in positive electrode particles.There are some conclusions can be made:（1） Compared with FOMe,FOMeS provides a more realistic response to the effect of electrode particle strain on lithium-ion concentration in electrode particles.（2） The aging battery experiments show that FOMeS accurately describes the stress trend of electrode particles and the loss of electrode capacity.（3） The electrode cracking model achieves the electrode particle crack growth simulation and predict the electrode particle crack growth trend.更多还原