DAISO is developing the all-solid-state lithium secondary battery for" ECO CUTE " in cooperation with Central Research Institute of Electric Power Industry( CRIEPI ). This is a new technology to support our life from the points of view of both energy and environment." ECO CUTE " is a hot-water supply system with CO2 heat pump which makes use of economical nighttime electric power. ECO CUTE needs large tank to store hot-water for one day. It is economic to heat minimum quantity of water at daytime using the secondary battery charged in nighttime. However, as a usual lithium ion secondary battery cannot be used at high temperature, it is necessary to separate from hot water tank and have larger space.
All-solid-state lithium secondary battery using solid polymer electrolyte can be used at high temperature (upper 60°C) and contribute to downsize of the space for the installation by integrating the battery and the water tank. This technology helps to support the electric power load leveling and to reduce the emission of greenhouse gas.
The solid polymer electrolyte is developed by the synthesis technique of a hydrin rubber ( Epichromer TM ) .The solid polymer electrolytes show high ionic conductivity and good electrochemical stability.The electrolytes can be used safely at high temperature. We propose the electrolyte as new electrolytes for lithium secondary battery.
- Ionic conductivity
- Polymer electrolyte exhibits high ionic conductivity (1×10-4 Scm-1 at 30°C)
- Electrochemical properties
- Polymer electrolyte exhibits 4V stable potential window versus Li+/Li and stable interface against lithium metal during the storage for a long time.
Polymer electrolyte film is crosslinked by heat or UV irradiation treatment. The crosslinked polymer electrolyte film has good mechanical properties and handling. The electrolyte film shows elastic behavior even at 150°C. The mechanical properties are stable during the storage in an inert gas even at 100°C.
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- <Film mechanical properties>
- Elongation at break : max. ca. 10 MPa
Elongation at break : ca. 100~900%
Modulus at 100% elongation:max. ca. 3 MPa
- <Film size>
- Thickness : 20~100µm
Width : 20cm (Roll seat)
- <Lithium salts>
- LiBF4, LiTFSI, LiBETI and so on.
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All-solid-state lithium secondary battery consists of the solid polymer electrolyte with no leaking fluid. It is safe with respect to ignition and explosion. The solid polymer electrolyte provides large freedom in designing the battery into different shapes.
Excellent cyclability with using Li Ni1/3Mn1/3Co1/3O2 *
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Test sample size : 2032 coin cell
Cathode material : LiNi1/3Mn1/3Co1/3O2
Anode material : Li metal
Test conditions : 60°C, C/8, 4.2-2.7 V
* Courtesy of CRIEPI |
Excellent reversibility at graphite electrode and solid polymer electrolyte interface*
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Test sample size : 2032 coin cell
Working electrode : Graphite
Control electrode : Li metal
Test conditions : 60°C, C/8, 0-2.5 V
* Courtesy of CRIEPI |
Good battery performance*
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Test sample size : 2032 coin cell
Cathode : LiNi1/3Mn1/3Co1/3O2
Anode : Graphite
Test conditions : 60°C, 12.3-7.5 V * Courtesy of CRIEPI |
Aluminum laminate battery of the size of 10×10cm (3stack)*
* Courtesy of CRIEPI
Gel electrolyte can be obtained by heat treatment (lead to chemical crosslinking) to fluid polymer electrolyte which is mixture of electrolyte and polymer. Gel electrolyte shows good elasticity and high ability of absorbance for liquid. The obtained electrolyte is expected to be useful materials for enlargement of lithium battery. Only 2% polymer is enough to obtain this gel electrolyte.
- Ionic conductivity
- It indicates high performance over wide range of polymer concentration.
Gel electrolyte at 3% polymer
