Lithium conducting ionic liquids based on lithium borate salts

• Published in: Journal of power sources Vol. 195; no. 18; pp. 6055 - 6061
• Main Authors: Zygadło-Monikowska, E., Florjańczyk, Z., Służewska, K., Ostrowska, J., Langwald, N., Tomaszewska, A.
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Amsterdam Elsevier B.V 15-09-2010; Elsevier
• Subjects: Applied sciences; Direct energy conversion and energy accumulation; Electrical engineering. Electrical power engineering; Electrical power engineering; Electrochemical conversion: primary and secondary batteries, fuel cells; Electrolytes; Exact sciences and technology; Ionic liquids; Lithium; Lithium borate salt; Lithium borates; Lithium conducting ionic liquids; Lithium electrolyte; Mathematical analysis; Matrices; Matrix methods; Polymer electrolyte; Sulfites; Polymer electrolyte; Lithium conducting ionic liquids; Lithium borate salt; Lithium electrolyte; Organic carbonate; Polymer electrolytes; Polymer solid electrolyte; Ionic liquid; Lithium battery; Ethylene oxide polymer; Organic borate; Lithium Borates; Polycarbonate
• ISSN: 0378-7753; 1873-2755
• DOI: 10.1016/j.jpowsour.2009.12.097

The simple reaction of trialkoxyborates with butyllithium resulted in the obtaining of new lithium borate salts: Li{[CH
3(OCH
2CH
2)
n
O]
3BC
4H
9}, containing oxyethylene substituents (EO) of
n
=
1, 2, 3 and 7. Salts of
n
≥
2 show properties of room temperature ionic liquid (RTIL) of low glass transition temperature,
T
g of the order from −70 to −80
°C. The ionic conductivity of the salts depends on the number of EO units, the highest conductivity is shown by the salt with
n
=
3; in bulk its ambient temperature conductivity is 2
×
10
−5
S
cm
−1 and in solution in cyclic propylene sulfite or EC/PC mixture, conductivity increases by an order of magnitude. Solid polymer electrolytes with borate salts over a wide concentration range, from 10 to 90
mol.% were obtained and characterized. Three types of polymeric matrices: poly(ethylene oxide) (PEO), poly(trimethylene carbonate) (PTMC) and two copolymers of acrylonitrile and butyl acrylate p(AN–BuA) were used in them as polymer matrices. It has been found that for systems of low salt concentration (10
mol.%) the best conducting properties were shown by solid polymer electrolytes with PEO, whereas for systems of high salt concentration, of the polymer-in-salt type, good results were achieved for PTMC as polymer matrix.