Making Safer Battery Separators with Ceramic Coatings

This patent describes how to make a special ceramic coating for battery separators using specific lithium-containing materials and a precise drying process to improve the safety and performance of lithium-ion batteries.

What it covers

The patent details a method to create a ceramic-coated separator for lithium-containing electrochemical cells, like those found in electric vehicles. It involves mixing a powder of specific lithiated oxides, such as Li2SiO3 or LiAlO2, with a binder to form a slurry with a controlled viscosity (Claim 1). This slurry is then applied onto a porous substrate, which acts as the base for the separator (Claim 1). Finally, the liquid is removed by drying the coated substrate at a temperature between 50°C and 100°C for 6 to 24 hours, forming a ceramic coating (Claim 1). This process aims to produce a separator that allows batteries to cycle at higher temperatures with reduced charge capacity loss (Claim 12). For instance, a manufacturer might use a doctor-blade coating method to apply a slurry containing LiNbO3 and carboxymethyl cellulose (CMC) onto a polymer film, then dry it in a controlled oven.

What it doesn't cover

• —Does not cover ceramic coatings made from non-lithiated oxides or other ceramic materials not specifically listed in Claim 1.
• —Does not cover manufacturing processes where the slurry viscosity falls outside the 300-1400 cps range at 25°C (Claim 1).
• —Does not cover drying processes that use temperatures outside the 50-100°C range or drying times outside the 6-24 hour range (Claim 1).
• —Does not cover separators where the ceramic coating is thicker than 10 μm (Claim 11).
• —Does not cover ceramic coatings applied to non-porous substrates (Claim 1).

The clever bit

The novelty lies in the specific selection of lithiated oxide materials for the ceramic coating and the precisely controlled manufacturing parameters. Using these specific lithiated oxides can improve ion conductivity and overall stability, while tight controls over slurry viscosity, drying temperature, and time ensure a thin, uniform, and effective protective layer on the separator.

Why it matters

Lithium-ion batteries are vital for electric vehicles and portable electronics, but safety issues like overheating and short circuits remain challenges. This patent offers a method to create a more stable ceramic coating for battery separators. Such coatings enhance thermal stability and mechanical strength, which can reduce the risk of internal short circuits and improve battery lifespan, especially under demanding conditions like high operating temperatures.

Real-world examples

• 1.Electric vehicle battery packs (e.g., General Motors Ultium batteries)
• 2.High-performance lithium-ion batteries for power tools
• 3.Batteries for consumer electronics (laptops, smartphones)
• 4.Grid-scale energy storage systems