기계공학부 구성원들의 많은 관심과 참여 부탁 드립니다.

▣ 주   제: Approach for fundamental understanding of mechanism of Lithium ion battery and its applications

▣ 연   사: 최종률 교수

▣ 소   속: Auburn University

▣ 일   시: 2022. 6. 8.(Wed) 14:30

▣ 장   소: 제4공학관 D602호  

▣ 초   청: 홍종섭 교수

▣ 초   록

  Efficiency of power generation and distribution can be substantially improved by employing

electrochemical storage devices that capture excessive energy and retrieve when needed. Particularly,

Lithium ion battery is the most preferred device because of high power and energy density. However,

advancement of materials and its complex structure of the battery becomes more challenging for R&D

engineers to understand the mechanism involved such as ion transport and intercalation/de-intercalation

processes in conjunction with heat generation and mechanical stress. In addition, degradation mechanism

is not well understood. Consequently, the battery systems are not overall optimally and safely designed and

operated.

  A group of researchers at Auburn University led by Dr. Choe has developed a high fidelity quasi three

dimensional and reduced one dimensional model for LiPB batteries based on multi-physics including

potentials, electrochemical, elastic and thermal theory, which allows for analysis of time dependent

transient behavior of ion concentrations, potential distributions, current density distributions and

temperature distributions and estimation of capacity and power fade. In addition, heat generation can be

accurately theoretically formulated and experimentally estimated. Newly developed multidimensional

calorimeter allows for not only estimation of heat generation rates, but also entropy coefficient accurately

and validating the theoretical behavior.

  In addition, the two major cause for degradation of the battery that lead to capacity and power fade are

side reactions and lithium plating that take place at anode particles. These phenomena are described using

electrochemical principles and integrated into the developed electrochemical-thermal model, so better

understanding of battery cell has been accomplished.

  In fact, the electrochemical thermal life models are very computational intensive and impractical for

real time applications because of partial differential and nonlinear equations. Therefore, the model is

simplified to a Reduced Order Model (ROM) by mathematical treatments that allows for embedding the

model in battery management systems (BMS). The major algorithms validated are such as estimation of

state-of-charge (SOC), state-of-health (SOH) and ultra fast charging methods, where advanced nonlinear

Kalman filters are applied to accurately estimate the internal states.

  Finally, the ROMs with the controls are experimentally validated in the Battery-In-The-Loop using

developed test stations and a large format Lithium ion polymer battery (Completed) and cylindrical cells

(On-going), where different characterization techniques have been developed and applied.

This presentation will provide an overview on approaches for the lithium ion battery cell and discuss

not only theoretical aspects, but also experimental methodologies to test and characterize cells.