Abstract
The decomposition of LiPF$_6$ electrolytes with water was studied by measuring the water content after storage. The solvents used are ethylene carbonate (EC) + diethyl carbonate (DEC), EC + dimethyl carbonate (DMC), propylene carbonate (PC) + DEC and PC + DMC. The experimental results were in good agreement with $-d[{\rm H}_2{\rm O}]/dt = k [{\rm H}_2{\rm O}]^2 [{\rm LiPF}_6]$. We obtained rate constant (k) from this empirical equation and rate constant (k) increased in the order of EC+DMC < EC+DEC < PC+DMC < PC+DEC. This order is inverse proportion to order of dielectric constant of these solvents. Non-ionized LiPF$_6$ dissociates to PF$_5$ and LiF in organic solvents and PF$_5$ reacts with water. High dielectric constant solvent increases the ionization of LiPF$_6$. Therefore, the reaction with water is suppressed in high dielectric constant solvent.
| Translated title of the contribution | Decomposition reaction of LiPF_6 based electrolytes for lithium ion cells |
|---|---|
| Original language | Japanese |
| Pages (from-to) | 281-288 |
| Number of pages | 8 |
| Journal | 九州大学大学院総合理工学報告 |
| Volume | 24 |
| Issue number | 3 |
| DOIs | |
| Publication status | Published - Dec 2002 |