Development and Verification of a Diagnostic Technology for Waste Battery Deterioration Factors.

ABSTRACT

We defined four major deterioration factors (electrolyte loss (EL), lithium loss (LL), lithium precipitation (LP), and compound deterioration (CD)). Then, we derived eleven key performance indicators (KPIs) for comparative analysis. After that, we fabricated three deteriorated cells for each of three deterioration factors (EL, LL, and LP) and one cell with CD (for verification) with four individual (dis)charging experiment manuals. The two major contributions of this study are the performance of 1) trend analysis to determine a suitable diagnostic metric by inspecting the eleven KPIs and 2) comparison analysis of V o c v , t ' ' ${{V}_{ocv,t}^{{ {^\prime} {^\prime}}}}$ and V o c v , t , s i m ' ' ${{V}_{ocv,t,sim}^{{ {^\prime} {^\prime}}}}$ to verify the effectiveness of utilizing V o c v , t ' ' ${{V}_{ocv,t}^{{ {^\prime} {^\prime}}}}$ as a real-time deterioration diagnostic factor using a concept of model-in-the-loop simulation. The results show that 1) V o c v , t ' ' ${{V}_{ocv,t}^{{ {^\prime} {^\prime}}}}$ has the most conspicuous trendline tendency among the eleven comparison targets for all four major deterioration factors, and 2) the angle difference between the two trends of V o c v , t ' ' ${{V}_{ocv,t}^{{ {^\prime} {^\prime}}}}$ and V o c v , t , s i m ' ' ${{V}_{ocv,t,sim}^{{ {^\prime} {^\prime}}}}$ lies within a minimum of 9° and a maximum of 43° (with a 10 4 ${{10}^{4}}$ sscale on the x-axis and a 10 - 7 ${{10}^{-7}}$ scale on the y-axis for a clear trend line analysis). From this, we can conclude that the trendline-based real-time deterioration analysis employing V o c v , t ' ' ${{V}_{ocv,t}^{{ {^\prime} {^\prime}}}}$ may be practically applicable to a limited extent.