Researchers at Deakin University’s Battery Technology Research and Innovation Hub have achieved stable operation of solid-state batteries using lithium metal anodes, a combination that promises significantly higher energy density than current lithium-ion technology while eliminating fire risks.

The work addresses two persistent challenges in battery technology. Lithium metal anodes store more energy per unit weight than the graphite anodes used in conventional lithium-ion batteries, but they form dangerous dendrites that can short-circuit cells. Solid electrolytes avoid the flammability of liquid electrolytes but have struggled with poor contact at interfaces with lithium metal.

Deakin’s solution involves a composite solid electrolyte that maintains intimate contact with the lithium metal anode throughout charge-discharge cycles. The batteries demonstrated stable performance for more than 1,000 cycles at energy densities 60% higher than commercial lithium-ion cells.

Why Solid-State Matters

Battery technology limits electric vehicle range, grid-scale energy storage capacity, and portable electronics runtime. Incremental improvements to lithium-ion chemistry have delivered steady progress, but the technology is approaching theoretical limits. New approaches are needed for substantial further gains.

Solid-state batteries replace the liquid electrolyte in conventional lithium-ion cells with solid ionic conductors, typically ceramics or specialised polymers. This eliminates the primary fire hazard in battery failures, where damaged cells can release flammable electrolyte that ignites.

Several companies and research groups worldwide are pursuing solid-state batteries, including Toyota, QuantumScape, and Solid Power. Most approaches face similar challenges: achieving sufficient ionic conductivity in the solid electrolyte, maintaining good contact between solid components, and enabling practical manufacturing.

The Deakin team’s work doesn’t solve all those challenges, but it demonstrates that stable lithium metal anodes are achievable in solid-state configurations. That’s significant because lithium metal anodes are required to realise solid-state technology’s full energy density advantage.

Technical Details

The composite electrolyte combines a lithium-conducting ceramic with a polymer that provides some mechanical compliance. The ceramic delivers high ionic conductivity, while the polymer maintains contact with the lithium metal anode as it expands and contracts during operation.

Lithium metal expands when the battery charges and contracts during discharge. In solid-state cells, this volume change can create gaps at interfaces, increasing resistance and degrading performance. The Deakin electrolyte accommodates these volume changes without losing electrical contact.

The research team also developed a modified manufacturing process that creates stronger initial bonding between the electrolyte and electrodes. Conventional battery manufacturing assembles components and fills the cell with liquid electrolyte, which penetrates porous electrodes. Solid-state manufacturing requires different approaches to achieve good interfacial contact.

Test cells demonstrated energy densities of 410 watt-hours per kilogram, compared to about 260 Wh/kg for current Tesla vehicle batteries. The higher energy density would enable longer vehicle range or lighter battery packs for the same range.

Cycle life exceeded 1,000 full charge-discharge cycles with less than 20% capacity fade. That’s not yet competitive with commercial lithium-ion cells, which target 2,000-3,000 cycles, but it’s sufficient to demonstrate the approach’s viability. Further optimisation should improve cycle life.

Manufacturing Challenges

The Deakin cells are laboratory prototypes about the size of a coin. Scaling to pouch cells large enough for vehicles or grid storage requires solving numerous manufacturing challenges. The ceramic-polymer composite electrolyte needs to be produced as thin, defect-free sheets at scale.

Current production methods use batch processing that wouldn’t be economical for large-scale manufacturing. The team is working with materials processing equipment suppliers to adapt continuous manufacturing approaches from the ceramic and polymer industries.

There’s also the question of whether existing lithium-ion battery factories could be retrofitted for solid-state production or whether entirely new facilities are needed. Some equipment and processes transfer, but others require fundamental changes.

Manufacturing costs remain uncertain until production processes mature. Solid-state battery proponents argue that eliminating liquid electrolyte and associated safety systems will offset higher material costs. Skeptics note that manufacturing process yields for new technologies are typically low initially, driving costs up.

Commercial Timelines

Professor Maria Forsyth, who leads Deakin’s battery research, said commercial solid-state batteries remain at least five years away, probably longer for applications demanding highest performance like electric vehicles. Consumer electronics and stationary storage might see solid-state products sooner.

Several companies have announced aggressive commercialisation timelines for solid-state batteries, but most have subsequently delayed those targets. The technology consistently proves harder to manufacture at scale than laboratory demonstrations suggest.

Toyota, perhaps the most advanced in solid-state development, now targets 2027-28 for limited production vehicles using solid-state batteries. Other automakers have hedged their bets, investing in solid-state research while continuing to improve lithium-ion technology.

For grid-scale energy storage, cycle life requirements differ from vehicles. Stationary batteries might charge and discharge once daily, accumulating far fewer cycles than vehicle batteries over their lifetime. That could make earlier solid-state technology viable for grid applications before it’s suitable for vehicles.

Australian Battery Industry

Australia has significant lithium mining industry but limited battery manufacturing capability. Most lithium mined here is shipped to China for refining and battery production. Developing domestic battery industry has been a policy priority, with mixed results.

Several initiatives aim to build Australian battery supply chains. Queensland government has invested in battery material processing facilities. Victoria supports research collaboration between universities and international battery companies. But large-scale battery manufacturing remains absent.

The challenge is competing with established Asian battery manufacturers who benefit from economies of scale, developed supply chains, and substantial production expertise. Australian facilities need compelling advantages to justify investment.

Solid-state technology potentially offers a reset point where established manufacturing advantage matters less. If production processes differ substantially from lithium-ion manufacturing, early-mover advantages could accrue to whoever masters the processes first.

That’s speculative though. More likely, Asian manufacturers will deploy solid-state production first, building on their battery manufacturing expertise. Australian researchers can contribute intellectual property through licensing but manufacturing will likely happen offshore.

Research Collaboration

Deakin’s battery hub collaborates with international research groups and companies. Partnerships with Warwick University in the UK and Pacific Northwest National Laboratory in the US provide access to specialised characterisation equipment and expertise.

Industry partnerships include relationships with Toyota, which funded some of the solid electrolyte research, and Australian mining companies interested in battery supply chains. These partnerships provide research funding while giving companies early access to technology developments.

Government funding comes primarily from the ARC and ARENA, Australia’s renewable energy agency. The investment reflects recognition that battery technology is critical for renewable energy systems and electric transport.

For organisations planning future battery technology roadmaps, understanding the pace of solid-state development matters for product planning and infrastructure investment. Technology strategy specialists can help assess competing battery technologies and realistic commercialisation timelines.

What’s Next

The Deakin team is working on larger cells and longer cycle life testing. They’re also investigating different electrode materials that might work better with their solid electrolyte system. Current prototypes use standard cathode materials, but solid-state configurations might enable different chemistries.

Collaboration with manufacturing equipment specialists aims to develop scalable production processes. That work is less scientifically glamorous than breakthrough research but equally important for commercialisation.

Solid-state batteries may eventually displace lithium-ion technology in many applications, or they may remain niche products for specialised uses. The Deakin research demonstrates meaningful progress on key technical challenges, but substantial work remains before solid-state batteries power vehicles or grid storage systems at scale.