IceBrick

images 1&2
Traditional Li-ion storage systems aren't safe neither for environment nor for humanity.

I didn't find a detailed explanation of their technology but I guess in a nutshell somehow their systems can store energy in the form of ice (charge phase) and then get that energy when needed by transforming the ice into the water (discharge phase).
They don't use rare/toxic materials.

it is 10 times more efficient in its energy density per square meter than any other available solution
source

They promise that their systems will have zero degradation for over 15 years of usage.
Also they will be

50% more cost effective
source

compared with traditional Li-ion systems

Important
They have already created a prototype and

Our first commercial demo system (400 kWh) will be up and running this coming September
source