New Polymer and Liquid Electrolytes for Lithium Batteries
All non-aqueous lithium battery electrolytes are Lewis bases that interact with cations. Unlike water, they don't interact with anions. The result is a high degree of ion pairing and the formation of triplets and higher aggregates. This decreases the conductivity and the lithium ion transference and results in polarization losses in batteries. Approaches that have been used to increase ion dissociation in PEO based electrolytes are the use of salts with low lattice energy, the addition of polar plasticizers to the polymer, and the addition of cation completing agents such as crown ethers or cryptands. Complexing of the anions is a more promising approach since it should increase both ion dissociation and the lithium transference. At Brookhaven National Laboratory (BNL) we have synthesized two new families of neutral anion completing agents, each based on Lewis acid centers. One is based on electron deficient nitrogen sites on substituted aza-ethers, wherein the hydrogen on the nitrogen is replaced by electron withdrawing groups such as CF{sub 3}SO{sub 3{sup -}}. The other is based on electron deficient boron sites on borane or borate compounds with various fluorinated aryl or alkyl groups. Some of the borane based anion receptors can promote the dissolution of LiF in several solvents. Several of these compounds, when added in equivalent amounts, produce 1.2M LiF solutions in DME, an increase in volubility of LiF by six orders of magnitude. Some of these LiF electrolytes have conductivities as high as 6 x 10{sup -3} Scm{sup -1}. The LiF electrolytes with borane anion acceptors in PC:EC:DEC solvents have excellent electrochemical stability. This has been demonstrated in small Li/LiMn{sub 2}O{sub 4} cells.
- Research Organization:
- Brookhaven National Lab. (BNL), Upton, NY (United States)
- Sponsoring Organization:
- USDOE Office of Energy Research (ER) (US)
- DOE Contract Number:
- AC02-98CH10886
- OSTI ID:
- 770781
- Report Number(s):
- BNL-67021; R&D Project: AS-114-MSD; KC-02-03-010; TRN: US0406929
- Resource Relation:
- Conference: 196. Meeting of the Electrochemical Society and 1999 Fall Meeting of the Electrochemical Society of Japan, Honolulu, HI (US), 10/17/1999--10/22/1999; Other Information: PBD: 29 Mar 1999
- Country of Publication:
- United States
- Language:
- English
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