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26 Oct 2024

The Solid-state EV Battery Journey Has Only Just Begun

26 Oct 2024  by clean technica   
The pace of electric vehicle sales continues to dismay some auto industry observers, but let’s get real. Compared to the evolution of the internal combustion engine, electric vehicles are rocketing up the automotive food chain. The latest example is a new anode-free, solid state EV battery from the US startup QuantumScape, which has just passed a key development milestone.

To put the EV sales picture into perspective, consider that the first ICE [internal combustion engine] vehicle to hit the streets under commercial production is credited to Germany’s Carl Benz, back in 1886, and nothing foundational has changed since then.

“By the 1890s, motor cars reached their modern stage of development. In fact, the models of that decade were so successful that there has been no fundamental change in the principles of the ordinary automobile engine since that time,” explains Distinguished University Professor of History and Director of the Institute for Public History at the University of Houston Martin Melosi.

Of course, the ICE field has seen plenty of modifications since the 1890s, but another important angle is affordability, and that hasn’t changed much over the past 100+ years either. The key step was switching from individual ground-up builds to assembly line production.

Although Henry Ford is commonly known for introducing assembly line affordability to ICE vehicles, the Automotive Hall of Fame ascribes the first use of a stationary assembly line to the Olds Motor Vehicle Company, which began mass producing its “Curved Dash” runabout all the way back in 1901.

To sum up, the modern ICE vehicle plying the roads today is supported by more than 120 years of engineering and manufacturing R&D. In contrast, the modern EV battery is based on lithium-ion technology invented in 1972.

To shorten the EV battery timeline even further, Li-ion batteries went through a series of flops and successes in the early 1970s. The first use of a Li-ion battery in an electric vehicle didn’t happen until 1998, when Nissan introduced the Altra EV.

Doing the math, the mass-producible lithium-ion EV battery of today only has about 26 years of R&D under its belt. Even less if you subtract from 2002, which was the year Nissan shut down production of the Altra EV. Tesla did not introduce the Roadster until 2008, but halted production in 2012 with less than 2,500 sales under its belt. The Model S finally launched in 2012 on a scale suitable for mass adoption. However, price parity with ICE vehicles was still a long way off, partly due to the high cost of the EV battery.

With that in mind, let’s take a quick look at the introduction of new solid state battery technology. All this time, lithium-ion EV batteries have relied on a liquid electrolyte based on a flammable solution. Energy storage innovators have engineered safety systems into the electrolyte, but concerns over fire hazards and performance limitations have motivated an investigation into glass, high tech ceramics, and other solid alternatives.

Solid-state batteries began surfacing on the CleanTechnica radar only about 10 years ago, one major hurdle being the stress that occurs when a solid material contracts and expands during charge-discharge cycles. One solution is to combine solid and non-solid layers, yielding a semi, quasi, or partially-solid architecture that some stakeholders prefer to describe simply as solid. This type of battery is already poised for mass production within the next few years. Many auto industry observers anticipate that an all-solid EV battery will soon follow.

By 2022, leading automakers were hammering out agreements with solid-state EV battery stakeholders before the ink even dried on the labwork. That brings us to QuantumScape, which entered into a strategic agreement with Volkswagen’s PowerCo electrification branch just a few months ago (see more QuantumScape background here).

In a public letter to shareholders posted on October 23, QuantumScape announced that it has begun producing B Samples of its new QSE-5 solid state EV battery cells, and shipping them to customers for testing. The company cites an energy density of more than 800 Wh/L (Watts per liter) for the QSE-5, along with fast-charging capability of less than 15 minutes, from 10% to 80%.

“QSE-5 represents an important milestone for our company and the battery industry as a whole. These cells are, to the best of our knowledge, the first anode-free solid-state lithium-metal cell design ever produced for automotive applications,” QuantumScape enthused, referring to a production process in which the battery cell is fabricated in a state of discharge. The anode then assembles itself during the first charging cycle.

“This cell is capable of simultaneously delivering exceptional performance with respect to energy density, discharge power, charging speed, low-temperature performance, and safety,” the company added.

Though QuantumScape also advised that B Sample testing involves a many months-long process of customer feedback and response, the company also affirmed that it has established the foundational design and performance profile of the new battery.

“We have to substantially improve on metrics such as cell reliability, yield and equipment productivity, among others,” QuantumScape noted, emphasizing that further tweaks are anticipated.

The final cost of the battery has yet to be determined, but QuantumScape’s proprietary production process should help contribute to the ongoing industry-wide trend of cutting costs.

QuantumScape notes that in order to improve its EV battery metrics during the B Sample phase, it is calling its Cobra separator process into production starting next year. Cobra is the successor to the company’s Raptor rapidfire, energy efficient heat treatment process.

Raptor has been deployed during the company’s lower-volume production schedule. The Cobra process will accommodate even higher production volumes and performance improvements, enabling QuantumScape to ship more samples out more quickly, thereby accelerating the customer feedback loop during the B Sample phase of QSE-5 testing.

It remains to be seen to what extent the new solid-state EV battery helps Volkswagen surge past Tesla in terms of US sales, but the company is already working as many levers as it can. In addition to its own own branded EVs, last summer Volkswagen inked a $5 billion deal with Rivian, and its new Scout Motors branch is readying mass production of an electric SUV and a pickup truck in 2027.

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