How Long Provisional Applications Hurt You

How Your Own Prior Art Can Kill You

I had a client whose inventor would write long provisional patent applications.  He would think through all the options of his inventions, and he would include every option he could conceive.

The company made battery separators – the thin sponge that goes between the anode and cathode of lithium ion batteries.  The inventor was one of the world’s foremost experts on lithium ion batteries and had decades of experience.  But he wrote terrible patent applications.

I got involved with the company about ten years after the first patent application was filed.  The inventor’s original patent thought through all the different additives that could be put in the separator.

One such additive was fibers.

Because the inventor was such an expert, he understood the issues that would probably pop up when adding fibers to the separator, but those issues were pretty much straightforward.  He did not include much description of how to deal with fibers. 

By the time I got involved with the company, the first patent application was granted and there were no continuation applications pending.  The company was a startup and did not invest in paying their patent attorney year after year to keep up these continuations.

We Found the Solution!

Several years went by and Boeing was having trouble with the batteries on their new 787.  These batteries were overheating, the separators were melting, and the batteries discharged their energy immediately, causing a fire.  This was before Samsung had cell phones that spontaneously combusted because of the battery separators.

We knew how to solve that problem: add fibers to the separator!

It turns out that fibers were very difficult to process.  First, the length of the fibers mattered.  Too long, and the fibers turned into a mass of spaghetti.  Too short, and the fibers did not do anything.

The fibers did not mix well when making the separator.  We had to test endless ways to apply sizing to the fibers to make them mix well, test different mixing conditions and methods, and so on.

When the separators were cast, the fibers all sank to the bottom, so we had to reinvent the casting process to keep fibers in the middle of the separator.

It took a full year of testing, failure, and experimentation to figure out how to do fibers.

The product worked.  I saw it at the factory, where we drove a nail right through a fully charged battery.  It got hot but never exploded.  There was no fire.  The fibers made a huge difference and solved an enormous problem.

So, we filed a patent application.

Our Prior Art Killed Us – Because of the Inventor’s Provisional Application

The patent examiner came back, citing our own provisional patent application from nearly 10 years before as prior art.  Our own inventor, by putting a bunch of extra material into his provisional patent application, unintentionally killed the most valuable patent asset we had.

At this stage in the company’s life, the company was running on fumes.  It had a strategic investor, but that money was running low.  With little IP protection on their most valuable innovation, the company eventually folded.

Lessons Learned: The Difference Between Chapter 7 and Chapter 11 Bankruptcy.

The lesson learned here: be very careful about what you put in the patent application because every word will hurt you.