Modeling for Mixed Solvent of Li-ion rechargeable battery

INTRODUCTION
Li-ion rechargeable battery is the cutting edge technology for all industries, especially automobiles and airplanes. To develop higher efficient battery, it is keen issue to develop advanced solvent as well as electrodes. At the same time, water in the solvent makes the battery efficiency worse. The solvent is made from mixing few types of esters, therefore NIR was found applicable for measuring concentration of water and each ester.
EXPERIMENTAL
20 samples were prepared by mixing test reagents commonly used as Li-ion rechargeable battery solvent. They are ethylene carbonate (EC), propylene carbonate (PC), dimethyl carbonate (DMC), ethyl-methyl carbonate (EMC), diethyl carbonate (DEC) and vinylene carbonate (VC). All six reagents were mixed in 0-30wt%. Water content was measured by a Karl-Fischer moisture meter. Each sample was put in a transparent cuvette cell of 10mm path length and measured by InfraSpec NR800 (Yokogawa Electric Corp.). The Unscrambler (CAMO As.) was used for analysis and modeling.
RESULTS AND DISCUSSION
All components had absorbance in 9000-4800cm-1. There were two types of peak. One was C-H related bond which did not interfere each other and the other was O-H and -O- related bond which interfered and did not follow Beer’s law. Models for each component and water were made with both types of peaks after the pre-treatment of baseline correction. Their accuracy (RMSEC) were as followed, less the one fiftieth of each lenge.
Range(wt%) RMSEC(wt%)
EC 18.3-29.4 0.167
PC 19.8-30.8 0.142
DMC 17.9-29.7 0.082
EMC 1.3-20.1 0.179
DEC 10.8-21.8 0.124
VC 0.0-1.2 0.019
Water 128-364ppm 9.4ppm