Merc starts solid-state battery road tests, aims for 1,000km EV – techAU

Mercedes-Benz has announced the start of road tests for a solid-state battery in a modified EQS sedan marks a significant step in EV technology, but it also reignites debates about the long-promised potential of solid-state batteries.

Solid-state batteries, which replace the liquid electrolyte in traditional lithium-ion batteries with a solid one, have been heralded as a transformative technology for EVs.

They promise higher energy density, improved safety by eliminating flammable liquids, and potentially longer lifespans. Mercedes-Benz, in collaboration with U.S.-based Factorial Energy and its subsidiary Mercedes AMG High Performance Powertrains (HPP) based in Brixworth, UK, has developed and patented a new solid-state battery pack.

This partnership, initiated in 2021, led to the delivery of the first B-sample cells in June 2024, with road tests commencing in February 2025, as per the press release dated February 24, 2025.

The test vehicle, a slightly modified EQS, integrates cells from Factorial Energy, known for its Factorial Electrolyte System Technology (FEST) platform.

This prototype aims to achieve a driving range of over 1,000 km (620 miles), a 25% increase over the current EQS 450+’s 800 km range, with a battery capacity potentially around 118 kWh, enhanced by a gravimetric energy density of up to 450 Wh/kg at the cell level.

Mercedes-Benz starts road testing first solid-state-battery vehicle // Mercedes-Benz startet Straßentests des ersten Fahrzeugs mit Festkörperbatterie

Technical Details and Innovations

The solid-state battery features several innovative aspects. It uses a lithium-metal anode, which, combined with a solid electrolyte, significantly outperforms conventional lithium-ion cells in energy density and safety.

A key innovation is the patented floating cell carrier, designed to manage volume changes during charging and discharging, where materials expand and contract.

Pneumatic actuators interact with these changes, supported by passive cooling, to improve efficiency and lifespan. This design, developed with HPP’s motorsport expertise, aims to transfer Formula 1 technologies into high-performance automotive applications, potentially accelerating development.

Benefits Highlighted

The press release emphasizes several benefits:

Safety: Eliminating liquid electrolytes reduces fire risk, a critical concern in EVs.
Weight Reduction: Higher energy density (450 Wh/kg) means lighter batteries, improving vehicle efficiency.
Range Extension: Up to 25% longer range compared to equivalent lithium-ion batteries, potentially reaching 1,000 km.
Efficiency: Passive cooling and reduced weight enhance overall driving efficiency.

These advantages could significantly boost EV adoption, addressing range anxiety and safety concerns, but their realization depends on overcoming production challenges.

Mercedes-Benz starts road testing first solid-state-battery vehicle // Mercedes-Benz startet Straßentests des ersten Fahrzeugs mit Festkörperbatterie

Skepticism and Historical Context

Despite the excitement, solid-state batteries have been promised for years without widespread commercialization. Historical data shows companies like Toyota, BMW, and Volkswagen have been researching them since the 2010s, with early attempts like Bolloré’s BlueCar in 2011 using lithium metal polymer batteries, but none have reached mass production for EVs yet.

Recent developments, such as Samsung SDI targeting mass production by 2027 and Panasonic focusing on drones by 2029, suggest progress, but timelines often slip.

Pricing remains unknown, and industry analyses, such as a 2023 Tech Briefs article, suggest a low penetration rate (3-5%) by 2030 due to challenges in performance, manufacturability, supply chain, and cost.

A 2024 IEEE Spectrum article warns of “production hell,” highlighting scaling difficulties, while a ScienceDirect study projects best-case prices at 140 USD per kWh by 2028, potentially competitive but higher than future lithium-ion costs (projected at 50-70 USD per kWh).

Challenges and Uncertainties

Several hurdles remain:

Production Scaling: Solid-state batteries require new manufacturing processes, such as high-pressure assembly for some designs, which could increase costs and complexity.
Cost-Competitiveness: Without clear pricing, it’s uncertain if they’ll be affordable compared to improving lithium-ion batteries.
Reliability and Lifespan: Long-term stability, especially under real-world conditions, needs validation, as dendrite formation and interface issues can degrade performance.
Market Readiness: Even with prototypes, the transition to customer cars involves regulatory approvals, supply chain setup, and consumer acceptance, all of which take time.

Comparative Analysis

To illustrate the state of solid-state battery development, consider the following table comparing key players and their timelines:

This table highlights the diversity in approaches and timelines, underscoring the uncertainty around Mercedes-Benz’s specific path.

Implications for the Future

If successful, Mercedes-Benz’s solid-state battery could set new benchmarks for EV range, safety, and efficiency, potentially accelerating adoption. However, given the historical delays and current uncertainties, it’s crucial to temper expectations.

The collaboration with HPP, leveraging Formula 1 tech transfer, is an unexpected detail that might expedite development, but it doesn’t guarantee overcoming production hurdles.

Over the next few months, Mercedes plans extensive lab and road tests, which will be critical in determining feasibility.

In conclusion, while the road tests are a promising step, the journey to customer cars is long, with no confirmed release date and unknown pricing adding to the skepticism.

This development aligns with broader industry trends, but as with past announcements, the real test will be in delivery, not just promise.