Wednesday, 31 May 2017: 17:20
Grand Salon D - Section 21 (Hilton New Orleans Riverside)
Solid state lithium-ion batteries are one of the promising candidates to power future electric and
hybrid electric vehicles. They offer outstanding safety and power density. The ability to exchange the
liquid electrolyte/separator system by a single component and use a metal lithium anode provides
encouraging advantages for the use of solid state batteries. In general a solid state electrode is
produced by dissolving the polymeric binder in a solvent and disperse the active material and
conductive additives in the solution. Commonly toxic solvents like n-methyl-2-pyrrolidion (NMP),
acetonitrile, methanol etc. are used in this process. Some of these are known to be carcinogenic and
often they have to be removed from the electrode, which results in energy consumption and further
process steps. The challenge is to develop a process which does not require any kind of such a solvent.
The present work investigates a solvent-free mixing and hot pressing technique to prepare both the
solid state lithiumironphosphate (LFP) cathodes and polyethylenoxide (PEO) based electrolytes. The
powder treatment is essential to produce mechanically stable and electrochemically active electrolytes
and electrodes. For the preparation, all ingredients were premixed in a dual asymmetric centrifugal
mixer and filled into a heated pressing die. Ideal process parameters such as pressure and heating time
were investigated. By way of example, figure 1 illustrates a flexible electrolyte film containing
PEO/LiTFSI with a molar ratio of 10:1. It can also be shown that the ionic conductivity of the solid
state electrolytes is in the same range (10-3 S/cm at 80°C) compared to their solvent based coated
counterparts. Additional determination of the electrolyte and electrode performance vs. Li anode is
made with respect to the discharge rate capability.
The lab-scale processing shown below demonstrates a first proof of function of all solid state cathode
and separator and may offer a much simpler method for such cathode and separator manufacturing
overall, with less process steps and potential cost saving and functional advantages. In conclusion, it
seems to be a promising process for further development to demonstrate scalability for future cell
production.
hybrid electric vehicles. They offer outstanding safety and power density. The ability to exchange the
liquid electrolyte/separator system by a single component and use a metal lithium anode provides
encouraging advantages for the use of solid state batteries. In general a solid state electrode is
produced by dissolving the polymeric binder in a solvent and disperse the active material and
conductive additives in the solution. Commonly toxic solvents like n-methyl-2-pyrrolidion (NMP),
acetonitrile, methanol etc. are used in this process. Some of these are known to be carcinogenic and
often they have to be removed from the electrode, which results in energy consumption and further
process steps. The challenge is to develop a process which does not require any kind of such a solvent.
The present work investigates a solvent-free mixing and hot pressing technique to prepare both the
solid state lithiumironphosphate (LFP) cathodes and polyethylenoxide (PEO) based electrolytes. The
powder treatment is essential to produce mechanically stable and electrochemically active electrolytes
and electrodes. For the preparation, all ingredients were premixed in a dual asymmetric centrifugal
mixer and filled into a heated pressing die. Ideal process parameters such as pressure and heating time
were investigated. By way of example, figure 1 illustrates a flexible electrolyte film containing
PEO/LiTFSI with a molar ratio of 10:1. It can also be shown that the ionic conductivity of the solid
state electrolytes is in the same range (10-3 S/cm at 80°C) compared to their solvent based coated
counterparts. Additional determination of the electrolyte and electrode performance vs. Li anode is
made with respect to the discharge rate capability.
The lab-scale processing shown below demonstrates a first proof of function of all solid state cathode
and separator and may offer a much simpler method for such cathode and separator manufacturing
overall, with less process steps and potential cost saving and functional advantages. In conclusion, it
seems to be a promising process for further development to demonstrate scalability for future cell
production.