BMW Group is continuing its advancement of research and testing in the field of next-generation battery technology, using a BMW i7 M70 as its rolling test bed.

In collaboration with American battery manufacturing company, Solid Power, the Group has announced that it has brought pure all solid-state battery (ASSB) cells to a special unit of its flagship sedan, which is now being operated around the Munich area.

The special unit of the i7 M70 is integrated with concept ASSB cells combining construction principles from BMW's current EV batteries and new module concepts from Solid Power

ASSBs have been widely regarded as the next frontier in battery technology, offering higher energy density in more compact storage systems compared to batteries currently used in modern EVs. For drivers, this is expected translate to lighter electric cars, more driving range, as well as faster charging speeds.

The concept ASSB cells integrated into the BMW i7 test vehicle were developed and manufactured by Solid Power in collaboration with experts from the BMW Group.

They are said to combine construction principles from BMW's own Gen5 batteries (which comprise prismatic cells in modules), and new module concepts for ASSB cell-integration from Solid Power. 

The two firms are hoping that the test programme will glean valuable insights into the use of sulfide-based electrolytes over the coming months

Both BMW Group and Solid Power have stated that the current real-world test aims to investigate the management of cell expansion, how the battery's operating pressure is controlled, and how to adjust the temperature conditions.

BMW Group also hopes that the test programme will reap valuable insights into the use of solid power cells with sulfide-based electrolytes - and their complete integration into a battery pack - over the coming months.

The latest announcement builds on BMW Group's technology transfer partnership with Solid Power, which was inked in 2022. The two companies have been cooperating since 2016 through a 'Joint Development Agreement'. BMW has committed to operating a solid cell prototype line at Solid power's Cell Manufacturing Competence Centre for research and development purposes, using Solid Power's experience and expertise. 

Speaking on the news, Martin Schuster, Vice President Battery Cell and Cell Module at the BMW Group, said: "Our BMW i7 ASSB test vehicle on the road is a perfect example of the BMW Group's technology-open mindset. We are continuously advancing the development of new battery cell technologies and are constantly expanding our know-how with valuable partners such as Solid Power."