You are working on the most urgent and important topic that I know of. But it is also very hard to pull through. I wish you the best success.

Here are two recent startups in the field with multi-million funding. They were serious approaches. Many people involved with good planning, etc. They still fizzled out when it came to installing their first capacity.

https://www.power-technology.com/news/newsgaelectric-receive...

https://www.greentechmedia.com/articles/read/lightsail-energ...

I believe a reason for the funding problems is the high uncertainty for the economics of storage. Electrical energy is traded in a market. And your trading strategy in the market has a big impact on whether you earn money. Without solid numbers for energy storage and the expected trading outcome, investors will have a hard time.