Functional Layer for Lithium-Ion Batteries

XPRIME is a refinement for current collectors in lithium-ion batteries to enhance their interfacial conductivity and passivate their surface.

Using our in-depth expertise in applying thin films, we have identified different approaches along the production chain of lithium-ion batteries to improve their performance and cost-efficiency by functionalizing cell component surfaces.

One of these technologies is XPRIME – a thin (<1µm) and dense coating on aluminum or copper current collectors. This coating increases both the power density and the lifetime of the latest lithium-ion batteries.

Enabling Passivation

combined with a dense XPRIME as protection against aluminum corrosion

Passivation of the Current Collector

  • Homogeneous, dense and non-particulate characteristics
  • Increased electrochemical stability
  • Supports innovative electrode processing approaches
  • Enables next generation cell concepts, such as high-voltage and all-solid state batteries

The use of alternative electrolyte systems is an important approach to circumvent existing challenges and to enable next-generation lithiumi-ion cells. While most commonly used LiPF6-based electrolytes show a high compatibility with the aluminum foil as a current collector, the use of other promising electrolyte systems lead to a corrosive decomposition of aluminum substrates.

To demonstrate the passivating properties of XPRIME, cyclic voltammetry measurements of refined aluminum foil as a cathode current collector vs. lithium have been performed using state-of-the-art and LiTFSI-based electrolyte systems. In these cells, the current density correlates with the electrochemical reactions of aluminum foil and the electrolyte. While the chemical properties of LiTFSI generally predestine it for the use in lithium-ion batteries, the oxidation of aluminum at upper voltages is still a problem. The results have been compared to measurements with blank aluminum and commercial primered foil.

LiPF6-based electrolyte system

The reactivity between XPRIME on aluminum foil and the electrolyte is minimized due to the passivating properties of the PVD functional layer compared to blank aluminum foil and a commercial, particle-based carbon primer. In detail, the in-situ formation of the fluoride containing passivation film on the aluminum is avoided by the XPRIME layer.

LiTFSI-based electrolyte system

The electrochemical stability of the aluminum-based current collector could drastically be increased by the XPRIME refinement. Thus, the surface corrosion of the aluminum foil in electrolytes with LiTFSI salt can be avoided by the XPRIME.

Increasing Conductivity

and reducing resistance between current collector and active material

Increased Power-Density and Lifetime of Lithium-Ion Batteries based on

  • Increased adhesion of active material
  • Reduced through-plane resistance of current collectors
  • Increased through-plane conductivity of the electrode