Professor Jürgen Janek, a leading figure in solid-state electrochemistry at Justus-Liebig University Giessen, discusses the past, present, and future of energy storage beyond lithium. His work, supported by the prestigious Post-Lithium Storage (POLiS) Cluster of Excellence, is at the forefront of developing next-generation battery technologies.
From History to High Conductivity: The Path to Solid-State Batteries
Janek’s journey into the field was almost accidental. Initially considering history, he ultimately chose chemistry, driven by fundamental gaps in existing knowledge. He credits early mentors with a strong physics and materials science background, as well as collaborations with Alan B. Lidiard, for shaping his perspective on ion transport in solids—a topic historically underrepresented in standard chemistry curricula. This realization that solid-state electrochemistry bridged physics, chemistry, and engineering propelled him toward a field he believed would become crucial for future energy technologies.
The Breakthrough That Accelerated Solid-State Research
One key turning point was Ryuichi Kanno’s 2011 report on high lithium-ion conductivity in the sulfide compound Li10GeP2S12 (LGPS). This discovery—conductivity exceeding that of liquid electrolytes—ignited rapid progress in solid-state battery concepts. Janek notes that this breakthrough sparked intense global competition for novel solid electrolytes, a race that continues today. Emerging research suggests even higher conductivity levels are achievable with sodium-based solid electrolytes, potentially enabling more sustainable, high-power batteries.
POLiS: Funding the Future of Energy Storage
The POLiS cluster, jointly run by the University of Ulm, Karlsruhe Institute of Technology, and Justus-Liebig University Giessen, is a major driver of this research. With a renewed seven-year funding period beginning in 2026, the program’s goal is to explore energy storage options beyond lithium, including sodium, potassium, magnesium, calcium, aluminum, and even anion-based systems. While lithium batteries will remain relevant, POLiS aims to diversify storage technologies to reduce reliance on a single element and increase resilience against geopolitical disruptions.
Recent Achievements: Imaging Metal Anodes and High-Conductivity Magnesium Electrolytes
Janek’s group contributes significantly to POLiS through in-depth studies of solid-state concepts, interface reactions, and charge transport. Recent work, led by PhD students Till Ortmann and Till Fuchs, has advanced microscopic imaging of sodium and lithium metal anodes using electron backscatter diffraction, opening new avenues for anode design. Clarissa Glaser’s research has also yielded promising results, synthesizing magnesium-ion solid electrolytes with conductivity reaching 0.1 mS/cm—a step toward viable magnesium-ion batteries.
The Crucial Role of Recycling
The program acknowledges that sustainability is non-negotiable. Janek emphasizes that recycling must be integrated into the design of new materials and cell concepts from the outset, ensuring a circular economy for these technologies.
Beyond Lithium: Predicting the Next Gigawatt-Scale Battery Technology
While predicting the future is uncertain, Janek suggests that sodium-ion batteries are poised to become the next widely adopted technology after lead, lithium, and sodium. Whether other “beyond lithium” chemistries—such as potassium, magnesium, or aluminum—will reach gigawatt scale depends on their performance and economic viability. POLiS is actively exploring these options, with the hope that one will emerge as a practical large-scale solution.
Improving Scientific Communication
Janek believes that scientific communication needs to evolve with the times. He advocates for open-access publishing with rigorous quality control and calls for more active discussion of published research, even suggesting the possibility of modifying or improving papers after publication—a concept that reflects the dynamic nature of modern science.
In conclusion, Professor Janek’s work and POLiS’s ongoing research represent a critical effort to diversify and enhance energy storage technologies. By focusing on materials beyond lithium and prioritizing sustainability, this research has the potential to reshape the future of power generation and consumption.
