| 초록 |
The ionic transport properties of solid polymer electrolytes can limit the performance of lithium batteries and are difficult to characterize. We established a numerical macroscopic model to determine the open circuit voltage (OCV) of the solid polymer electrolyte (SPE) in lithium secondary battery by thermodynamic approach. Since SPEs are high concentrated electrolyte different from liquid electrolyte, the model must be the concentrated solution theory that has transport properties and thermodynamic activity factor allowing the use of concentration-dependent parameters. Previous model treats this concentration dependence expanding as simple polynomials, so there are parameters that have no meaning. To give physical meanings to these parameters, we approached the activity factor by MDL-NR model. Using this thermodynamic model enables us to describe the specific interactions and the nonrandomness effect in predicting the OCV of SPE. In this work, only thermodynamic part is considered, so transport parameter (cationic transport number) is treated as constant. Data of ethylene and propylene oxide copolymer with 0.11-2 M LiTFSI are used to compare the proposed model with the previous model. The study resulted by the proposed model well suits for the systems that can easily be used to simulate the electrolyte behavior for the OCV. |
