BMW i7 Trials Advanced Solid-State Battery Technology

Earlier this week, we saw a camper loaded with solid-state battery power, and now a luxury electric vehicle is showcasing its own advanced energy storage. BMW is currently testing solid-state batteries in its i7 electric sedan. These sulfide-based batteries offer greater energy density, enhanced safety, and a more compact, flexible design compared to conventional lithium-ion batteries.

This week, BMW revealed that it is testing prototype all-solid-state battery (ASSB) cells—developed by Colorado-based battery company Solid Power—in its i7 electric sedan around the Munich area.

According to BMW, the batteries under testing feature prismatic cells paired with innovative new module designs. The road tests aim to evaluate how the batteries handle cell expansion, pressure during operation, and varying temperature conditions.

Solid Power CEO Highlights Milestone as BMW Stresses “Truly” All-Solid-State Battery Tech

John Van Scoter, president and CEO of Solid Power, stated, “We’re incredibly proud that our collaboration with BMW has led to the first real-world demonstration of genuine all-solid-state battery cells in a vehicle.”

BMW and Solid Power are careful to repeatedly emphasize terms like “all-solid-state” and “truly” solid-state in their announcement—so much so that it’s easy to lose track of how often “ASSB” is mentioned. This emphasis is likely, at least in part, a response to a similar claim made earlier this year by BMW’s rival, Mercedes-Benz. In February, Mercedes announced it had begun testing solid-state battery cells in its electric flagship, the EQS.

However, there’s a key difference: the batteries Mercedes is testing, based on Factorial Electrolyte System Technology (FEST), use a quasi-solid or semi-solid electrolyte. That means they aren’t technically “all-solid-state” since they still contain some liquid. Factorial describes their electrolyte as a hybrid—a solid framework infused with a liquid or gel-like substance. This approach is said to offer better thermal stability and lower flammability than traditional liquid electrolytes, while also providing smoother ion flow and simpler manufacturing compared to fully solid-state designs.

Factorial is developing its own ‘Solstice’ all-solid-state battery that features a sulfide-based electrolyte, but they consider this a next-generation technology. It was only announced in September, several months after Factorial had already delivered FEST battery samples to Mercedes for advanced testing.

BMW and Solid Power Lead in Fully All-Solid-State Batteries, but Market Success Still Up for Grabs

The solid-state progress we’ve observed from Chinese automakers such as IM has mostly involved semi-solid-state batteries. Therefore, BMW and Solid Power appear accurate in claiming they are the first to integrate fully all-solid-state batteries into a production vehicle.

That said, the difference is mostly theoretical right now. Ultimately, the only “first” that will matter is which automaker successfully brings solid-state battery technology to market. China currently leads in this area, but being the first to launch semi-solid and all-solid-state battery vehicles in Western markets like the US will also be a significant achievement—especially if it’s in a compelling, affordable car platform.

BMW and Solid Power Expand Partnership to Advance Sulfide-Based Solid-State Battery Technology

Since 2016, BMW has been collaborating with Solid Power to develop solid-state batteries. Solid Power employs a sulfide-based solid electrolyte instead of the flammable liquid electrolytes found in conventional lithium-ion EV batteries. This thin solid sulfide layer functions both as a barrier preventing contact between the anode and cathode and as a conductive electrolyte that enables ions to transfer between them.

In December 2022, BMW and Solid Power strengthened their partnership by signing an expanded joint development agreement. Under this deal, Solid Power licensed BMW Group to use its all-solid-state cell design and manufacturing expertise for research and development purposes. This collaboration has enhanced joint efforts in advancing the research, development, and production of solid-state technology.

As part of the agreement, BMW will run a prototype production line for solid-state cells at its Cell Manufacturing Competence Center in Parsdorf, Germany. We will model this production line after Solid Power’s pilot lines located in Colorado.

Solid Power’s Promising Battery Specs

BMW hasn’t shared detailed information about the specific cells they are testing, but Solid Power claims their batteries offer energy densities ranging from 390 to 560 Wh/kg, depending on the materials they use for the anode and cathode. They estimate the volumetric energy density to be between 785 and 930 Wh/L. Solid Power also projects a cycle life exceeding 1,000 cycles for all battery chemistries and highlights the enhanced safety of their all-solid-state design.

Although road testing plays a crucial role in launching solid-state batteries, BMW acknowledged in this week’s announcement that they still need to take further development steps to implement ASSB technology in a competitive overall storage system. In other words, BMW doesn’t expect the solid-state i7 to hit dealerships anytime soon.

Read the original article on: New Atlas

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