ALD Coating for Li-ion Battery Materials

ALD Coating for Enhanced LiB Performance

Targray’s ALD coating solution is a proven thin-film deposition technology that enhances the electrochemical performance of cathode powders (NMC, NCA, LCO, LMO, LMNO) and anode powders (Graphite, Graphene, LTO, Si, Si-C composites) in lithium-ion battery cells and battery packs. Applied via a patented sequential chemical surface modification process, our pinhole-free anode and cathode coating has been shown to:

• Enhance the rate capability, safety & longevity of li-ion battery cells, packs.
• Deliver increased voltages without negatively impacting cycle life.
• Increase energy by 20% and battery cycle life by as much as 300%
• Yield better overall battery performance at a lower manufacturing cost.

Increasing the Safety of Lithium-ion Batteries

Targray ALD coated cathodes and anodes demonstrate exceptional safety benefits in lab settings. The figure to the left illustrates the increased thermal runaway onset temperature demonstrated by an ALD coated material (40Ah NMC-graphite cell). The safety benefits of ALD coating, outlined below, can protect batteries against a number of processes that lead to catastrophic failure events. Moreover, they can be realized even for relatively stable chemistries when used in large format pouch cells.

• Reduction of gas and heat generation during cycling.
  
• Suppression of autocatalytic reactions that cause heat generation at increased temperatures.
• Reduction of heat generation in nail penetration events.
• Increase of thermal runaway onset temperature.
• Resistance of dendrite growth.
  

ALD Coated Cathode Materials

 Coated NMC Cathodes

Targray ALD coating can be applied to cathode active materials to produce long cycle life core-shell cathodes. The cycle life benefits of ALD coating are clearly demonstrated in NMC 811 cathodes. When paired with a conventional graphite anode in a 2.4 Ah pouch cell, cycled to 4.35V at room temperature and at C/3-C/3 charge-discharge rates, the ALD coated NMC 811 enabled: 

• Prolongation of the cell’s lifetime by 30-40%.
• Leveraging of increased charge voltage to use > 200 mAh/g cathode materials.
• Suppression of the capacity fade found in the Lithium- and Manganese-rich NMC.

Coated NCA Cathodes

The figure to the right directly compares the similarity in cycle life of an ALD coated NCA cathode charged to 4.4V, relative to their pristine NCA charged to 4.3V (in half cells). A further increase in capacity due to elevated temperature operation is realized when using ALD-enabled NCA. By leveraging the additional value that our ALD coating solution provides, device manufacturers can achieve their desired energy density cell at a lower overall cost.

ALD Coated Anode Materials

Targray’s ALD coating solution can be applied to our natural and artificial graphite powders to create drop-in ready solutions for current lithium-ion anode chemistries. As the degradation mechanisms for anodes and cathodes are different (albeit intertwined), cells comprising both ALD coated anodes and cathodes can deliver compounding benefits.

Left: Targray ALD coatings allow Nickel-rich NMC and graphite dual ALD cells to be safely cycled to 4.4V, achieving the same degree of robustness as pristine cathodes cycled at 4.2V with 100% DOD.

This added stability delivers an increase in energy density of approximately 15-25%, while still delivering a room temperature equivalent cycle life exceeding 2,200 cycles.

Contact the Battery Division