Dense 3D Nanoscale Electrode Batteries with a Conformal Solid Electrolyte
Using dense, 3-dimensional (3D) arrays of nanoscale cathodes and anodes offers the potential to increase the areal energy density of rechargeable batteries for electric vehicles by at least an order of magnitude. However, developing batteries with such fine-scale patterns requires the development of electrode processing methods and a conformal solid electrolyte material that pasivates the large amount of interfacial surface area in 3D electrode and that also serves as a very thin, but durable separator between the cathode and anode. 3D electrodes have a high surface area to volume ratio so stabilizing the solid surface is critical. Suitable conformal solid electrolytes are not yet available and need to be developed. To solve this limitation, TDA Research has developed a durable nano-porous polymer material that is easily applied as a conformal artificial SEI or solid electrolyte for 3D batteries. The material is based on an ionically conductive, nanoporous polymer that can be coated or inserted as a liquid into the small gaps between electrode features prior to in situ self-assembly and solidification. When it cures, the new material both bonds electrodes together and keep them physically separated by a thin, highly conductive conformal material. The material passivates the high voltage cathode solid interface and prevent poorly conductive SEI formation during long-term cycling. This Phase I project successfully developed this conformal solid electrolyte and demonstrated it on 3D LFP electrodes with high areal density. In spite of the increased electrode surface area, the new batteries had excellent SEI performance and long-term cycling. This is critical because the benefits of the higher areal energy density can only be realized if the 3D battery has a stable cycling behavior long-term. In order to test our conformal electrolyte we needed to produce 3D patterened cathodes. We developed a new laser ablation method to rapidly produce 3D micro-patterned lithium iron phosphate (LFP) cathodes that we used to demonstrate the improved properties of our conformal solid electrolyte. Our solid electrolyte may be used as a thin artificial SEI layer, or as the bulk solid electrolyte. It is based on a self-assembled, cure-in-place, nanoporous polymer with ion-conducting nanochannels. This artificial SEI has a remarkably low charge transfer resistance (~1 Ohm after 100 cycles) which is orders of magnitude lower than the charge transfer resistance of the native SEI that naturally forms between the LFP and typical carbonate or ionic liquid solvents. We proved that the new conformal solid electrolyte combined with the 3D micro-patterned LFP cathode improved the usable capacity of thick LFP cathodes (99.6% usage of the active material in a 150 micron thick LFP cathode after 100 cycles). The Phase I project proves that our material is capable of acting as the artificial SEI and conformal electrolyte that is needed for the next generation 3D, high areal energy density lithium batteries. Our commercialization strategy is to initially produce the monomers and use them to coat commercial LFP cathodes and Si/C anodes that we process by laser ablation to create the 3D micropatterning. We also plan to work with our partner, SAFT, to provide 3rd party validation of our prototype cathodes / anodes and to assist in scaling up battery production to include pouch cells. Ultimately, TDA will license the technology to a battery producer and continue to produce and supply the monomers needed to produce the new solid conformal electrolyte. TDA has licensed the composition of matter patent that covers the monomers from the University of Colorado.
- Research Organization:
- TDA Research, Inc.
- Sponsoring Organization:
- USDOE Office of Science (SC)
- DOE Contract Number:
- SC0022417
- OSTI ID:
- 1900035
- Type / Phase:
- SBIR (Phase I)
- Report Number(s):
- R-2101-037-F
- Country of Publication:
- United States
- Language:
- English
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