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05:33
Solid-state Graft Copolymer Electrolytes for Lithium Battery Applications
Published on: August 12, 2013
Alkali metal crystalline polymer electrolytes
Chuhong Zhang1, Stephen Gamble, David Ainsworth
1EaStCHEM, School of Chemistry, The Purdie Building, University of St. Andrews, KY16 9ST, UK.
Nature Materials
|June 23, 2009
Summary
New crystalline polymer electrolytes demonstrate ionic conductivity, challenging previous assumptions. Researchers discovered novel materials with enhanced conductivity, expanding possibilities for solid-state devices.
Area of Science:
- Materials Science
- Electrochemistry
- Polymer Science
Background:
- Polymer electrolytes combine ionic conductivity with mechanical flexibility, crucial for solid-state devices.
- Historically, ionic conductivity in polymers was thought to occur only in amorphous states above the glass transition temperature (Tg).
- Crystalline polymers were generally considered insulators, with Li(+) conductivity in crystalline poly(ethylene oxide)(6):LiAsF(6) being a notable exception.
Purpose of the Study:
- To investigate if ionic conductivity in crystalline polymers is unique to the poly(ethylene oxide)(6):LiAsF(6) complex.
- To discover new crystalline polymer electrolytes beyond the established 6:1 complex.
- To explore the potential of different alkali metal salts in crystalline polymer electrolytes.
Main Methods:
- Synthesis and characterization of new crystalline polymer electrolytes.
- Incorporation of various alkali metal salts (Na(+), K(+), Rb(+)) into polymer matrices.
- Measurement and comparison of ionic conductivity in the novel crystalline systems.
Main Results:
- Demonstration that ionic conductivity is not exclusive to the 6:1 complex in crystalline polymers.
- Discovery of several new crystalline polymer electrolytes with different alkali metal salts.
- Identification of poly(ethylene oxide)(8):NaAsF(6) as the best-performing conductor, exhibiting conductivity 1.5 orders of magnitude higher than poly(ethylene oxide)(6):LiAsF(6).
Conclusions:
- Ionic conductivity can be achieved in crystalline polymers beyond the specific 6:1 lithium complex.
- The findings present the first crystalline polymer electrolytes with compositions and structures distinct from the 6:1 Li(+) complex.
- This opens new avenues for developing advanced solid-state devices utilizing novel crystalline polymer electrolytes.
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Group 1 elements are soft and shiny metallic solids. They are malleable, ductile, and good conductors of heat and electricity. The melting points of the alkali metals are unusually low for metals and decrease going down the group, while the density increases going down the group with the exception of potassium (Table 1).
Table 1: Properties of the alkali metals
Table 1: Properties of the alkali metals
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