Multi‐objective optimization of lithium‐ion battery pack casing for electric vehicles: Key role of materials design and their influence

• Published in: International journal of energy research Vol. 44; no. 12; pp. 9414 - 9437
• Main Authors: Zhang, Yihui, Chen, Siqi, Shahin, M.E., Niu, Xiaodong, Gao, Liang, Chin, C.M.M., Bao, Nengsheng, Wang, Chin‐Tsan, Garg, Akhil, Goyal, Ankit
• Format: Journal Article
• Language: English
• Published: Bognor Regis Hindawi Limited 10.10.2020
• Subjects: Aluminium; Aluminum; Aluminum base alloys; battery pack casing; Braking; Carbon nanotubes; Design; Design optimization; electric vehicle; Electric vehicles; Equivalence; Lithium; Lithium-ion batteries; mechanical performance; Mechanical properties; multi‐objective optimization; Performance standards; Resonance; Response surface methodology; Stress; Vibration; Weight reduction
• ISSN: 0363-907X; 1099-114X
• DOI: 10.1002/er.4965

Summary The battery box is the structure that comprises the battery cells and its casing. It is designed to fix and protect the battery module. During the actual driving, there exists stress and resonance on a battery pack and its outer casing due to external vibration and shock. The safety of an electric vehicle largely depends on the mechanical characteristics of its battery pack. Besides, a lighter weight electric vehicle has a longer driving range, which makes it much more popular in vehicle market. In this paper, a comprehensive design procedure based on multi‐objective optimization and experiments is applied to compare the maximum equivalent stress and resonance frequency on a battery pack casing with different materials (DC01 steel, aluminum 6061, copper C22000, and carbon nanotube [CNT]) under bumpy road, sharp turns, and sudden braking conditions to obtain the best material. Moreover, CNT is proved to be the best material considering all the performance standards. Response surface optimization design method is adopted to get an optimal design of the battery pack casing. Optimization results conclude that the maximum equivalent stress can be reduced from 3.9243 to 3.2363 MPa, and the six‐order resonance frequency can be increased from 722.65 to 788.71 Hz. Experiments are carried to validate the mechanical performance of the optimal design; the deviation between the simulation and experimental results is within the tolerance. By 2025, the demand of lithium for chargeable and nonchargeable batteries is expected to reach 212 000. Therefore, the safety of an electric vehicle largely depends on the mechanical characteristics of its battery pack. In addition, a lighter weight electric vehicle has longer driving range, which makes it much more popular in vehicle market. In this paper, a comprehensive procedure based on finite element analysis is applied to compare the maximum equivalent stress, total deformation, and resonance frequency on a battery pack casing with different materials under parking, bumpy road, sharp turns, and sudden braking conditions to obtain the best material. Although aluminum 6061 is tested to have lower maximum equivalent stress, carbon nanotubes (CNT) is proved to be the best material considering all of these three performance standards. Then, response surface optimization design method is adopted to get an optimal design of the battery pack casing. Optimization results concluded that the maximum equivalent stress can be reduced from 3.9243 to 3.2363 MPa, and the six‐order resonance frequency can be increased from 722.65 to 1040.751 Hz.