Coreshell Technologies, Inc. is developing a low-cost thin-film coating process that integrates seamlessly into existing lithium-ion battery (LIB) manufacturing in order to increase energy density, improve battery lifetime, and substantially reduce the cost per kWh of stored energy. The technology, when fully commercialized, will greatly improve the cost-competitiveness of LIB-based technologies with far-reaching impacts on applications such as electric vehicles (EVs) and stationary energy storage.

Coreshell’s technology is based on a proven concept with substantial literature precedent over the past decade. Thin-film coatings, when applied directly to electrode surfaces, are known to protect LIBs against degradation reactions that typically reduce capacity during charge-discharge cycling. As a result, LIBs that possess protective coatings can be cycled under typical operating conditions for greater numbers of cycles, or alternatively, can be charged and discharged more aggressively without sacrificing lifetime.

Protective coatings work by preventing the formation of an electrode surface-degradation product known as “solid-electrolyte-interphase” or “SEI”. Since SEI is composed primarily of lithium-containing compounds, its formation is the primary cause of lithium-loss (and therefore, capacity loss) during battery cycling.

However, until now, protective coatings have only been applied to lithium-ion electrodes using costly, time-consuming vacuum deposition techniques such as Atomic Layer Deposition (ALD). ALD, due to its high upfront cost of capital and slow throughput, is inherently not scalable to high-volume “roll-to-roll” (R2R) lithium-ion battery manufacturing.

Coreshell’s innovation, in contrast, is to apply coatings to lithium-ion electrode surfaces using low-cost, atmospheric, solution-phase coating techniques. Such techniques have been scaled to other high-volume R2R industries in the past (such as flexible thin-film solar and polymer membranes) and have provided high-quality, uniform thin-films of various materials across a variety of substrates.

In this Phase I project, Coreshell demonstrated a significant improvement in capacity retention of state-of-the-art LIBs, when cycled within an aggressive voltage window of 3-4.4V, through the application of solution-phase-deposited protective thin films on electrode surfaces. In fact, the result demonstrates an achievement of industry-standard cycle lifetimes for applications such as electric vehicles while simultaneously boosting LIB energy density by 20% through the enablement of an elevated upper voltage cutoff. This increase in energy density can then result in a commensurate reduction in LIB cost/kWh, thereby removing economic barriers to clean energy applications such as electric vehicles and stationary energy storage. Furthermore, the technique of using solution-phase deposition to grow high-quality conformal thin films of various materials on all surfaces throughout the porous microstructure of typical battery electrodes was confirmed via cross-sectional electron microscopy. Finally, the results of this Phase I project indicate that solution-phase deposition represents a viable alternative to the costly, slow methods of vapor-phase deposition utilized in the prior art for growth of protective thin films on LIB electrode surfaces in both state-of-the-art batteries as well as future electrode chemistries that have yet to be commercialized.

Last Modified: 04/01/2020
Modified by: Sourav R Basu