Effect of electrolyte composition on the performance of sodium/polymer cells
- Lawrence Berkeley Lab., CA (United States)
- Umeaa Univ. (Sweden). Dept. of Experimental Physics
The dependence on Na/P(EO){sub n}NaX/Na{sub x}MnO{sub 2} (P(EO) = poly(ethylene oxide), X = CF{sub 3}SO{sub 3} or (CF{sub 3}SO{sub 2}){sub 2}N) cell cycle life and rate capability on polymer electrolyte composition is described. Transition time experiments and mathematical modeling indicate that failure due to salt precipitation occurs at it{sup 1/2} = 10.5 to 21.4 mA s{sup 0.5}/cm{sup 2}, when high initial concentrations of NaCF{sub 3}SO{sub 3} are used in operating cells. Evidence for large ionic clusters in concentrated PEO/NaCF{sub 3}SO{sub 3} solutions is also seen in the Raman spectroscopic data. Salt precipitation is a direct consequence of the concentration gradients that arise during operation, due to the negative cationic transference numbers (t{sub +}{sup 0}) of the binary salt/polymer electrolyte. By decreasing the initial salt concentration, t{sub +}{sup 0} is increased, cell rate capability is doubled, and the cycle life is enhanced nearly threefold. Similar improvements are obtained when PEO/NaN(CF{sub 3}SO{sub 2}){sub 2} electrolytes are used.
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- AC03-76SF00098
- OSTI ID:
- 465081
- Journal Information:
- Journal of the Electrochemical Society, Journal Name: Journal of the Electrochemical Society Journal Issue: 2 Vol. 144; ISSN JESOAN; ISSN 0013-4651
- Country of Publication:
- United States
- Language:
- English
Similar Records
Electrochemical insertion of sodium into carbon
Measurements of the thermal conductivity of poly(ethylene oxide)-lithium salt electrolytes