A practical approach to predict volume deformation of lithium‐ion batteries from crystal structure changes of electrode materials

Abstract

Volume deformation of lithium-ion batteries is inevitable during operation, affecting battery cycle life, and even safety performance. Accurate prediction of volume deformation of lithium-ion batteries is critical for cell development and battery pack design. In this paper, a practical approach is proposed to predict the volume deformation of lithium-ion batteries. In the proposed method, the deformation of a full cell is determined as the superposition of the thickness changes of cathodes and anodes, which are induced by the expansion/ contraction of crystal structure during lithiation/de-lithiation. The electrodes' crystal volume changes are calculated based on the evolution of lithium stoichiometry in cathode and anode, which can be identified through the reconstruction of the battery charging voltage profile. Finally, the thickness changes of cathode and anode as well as the deformation of the full cell are predicted. The proposed method can achieve accurate predictions of the deformations of lithium-ion batteries with various chemistries, with the predicted errors less than 10%. Moreover, the proposed method can help to interpret the differences in deformation profiles of batteries with different chemistries, and provide useful guidance for cell development.

Estimation of NCM111 /graphite acoustic properties under different lithium stoichiometry based on nondestructive acoustic in situ testing

“…There are two core elements for cathode and anode volume change during charging and discharging: state of Li stoichiometry and volume change variation of active materials under different Li stoichiometry. [42][43][44][45] Based on Equations ( 4) to ( 6), the variations in the Li stoichiometry of the cathode and anode can be identified through the reconstruction of the battery charging voltage profiles. U sim is the simulated full-cell voltage, which comprises a polarization voltage due to the impedance R, cathode voltage U ca , and anode voltage U an .…”

“…The minimum root mean squared errors (RMSE) of the simulated full-cell voltage and real full-cell voltage under all n sampling points are calculated using the genetic algorithm and Equation (7) to finally obtain the optimal solution of [y 0 , C ca , x 0 , C an , R] and [y 0 100 , C 0 ca ,x 0 100 , C 0 an , R]. 42,46…”

“…k vca and k van indicate the theoretical volume change rate of the cathode and anode materials under different Li stoichiometry vs 0% SOC, they can be obtained from related studies. [42][43][44][45] t ca and t an indicate the monolayer thickness of cathode and anode materials at 0% SOC, with N being the number of layers of active materials involved in the Li-ion migration. In general, the number of layers of the anode is one more than the cathode ones, but the external layer of the anode materials does not play a role in the reaction, thus, N is equal to the number of cathode material layers.…”

Preparation and electrochemical properties of Al‐F co‐doped spinel LiMn 2 O 4 single‐crystal material for lithium‐ion battery

“…[1][2][3][4][5] The cathode materials of lithium-ion batteries play a vital role in their charge-discharge specific capacity and voltage. [6][7][8][9] Nowadays, commercial cathode materials for lithium-ion batteries mainly include LiCoO 2 , LiNi x Co y Mn z O 2 , LiFePO 4 , and LiMn 2 O 4 . [10][11][12] Compared with other materials, spinel LiMn 2 O 4 has the advantages of high specific energy, environmental friendliness, high safety, and low price, so it is considered as one of the most promising cathode materials for lithium-ion batteries.…”

“…Lithium‐ion batteries have been widely used in portable electronic devices, electric vehicles, hybrid electric vehicles, and other fields because of their high energy density, good cycle stability, and long service life 1‐5 . The cathode materials of lithium‐ion batteries play a vital role in their charge‐discharge specific capacity and voltage 6‐9 . Nowadays, commercial cathode materials for lithium‐ion batteries mainly include LiCoO 2 , LiNi x Co y Mn z O 2 , LiFePO 4 , and LiMn 2 O 4 10‐12 .…”