Periodic Reporting for period 2 - HELENA (Halide solid state batteries for ELectric vEhicles aNd Aircrafts)
Reporting period: 2023-12-01 to 2025-05-31
The next generation in electric vehicle batteries will probably see the replacement of lithium-ion batteries with higher-performing alternatives. It is therefore crucial to develop different types of solid-state batteries to fulfil the growing energy density requirements. Generation 4b batteries have higher energy densities and longer ranges. The EU-funded HELENA project will respond to the need for a safe, high energy efficiency solid-state battery cell. Researchers are looking to produce a Generation 4b battery with a high-energy density lithium metal anode, a nickel-rich nickel–manganese–cobalt cathode and a superionic halide solid electrolyte. Project activities should enable low-cost, scalable and safe cell manufacturing and fast battery charging, thereby boosting the electric vehicles’ driving range.
At month 36, the HELENA project has made substantial progress across its work packages.
WP1 continued overseeing project monitoring, quality control, and risk management. WP2 advanced testing and validation of HELENA battery cells for automotive and aerospace applications, integrating new aircraft concepts. WP3 focused on improving halide solid electrolytes, developing In-doped Li₃Y₀.₉₇In₀.₀₃Cl₄Br2 and selecting compatible cathodes (NMC622, NMC811). Several strategies were tested to stabilize the lithium–halide interface, but none fully succeeded. WP4 fabricated cell components and optimized extrusion processes, concentrating on 40 mAh monolayer pouch cells. WP5 defined handling conditions for raw materials and assessed humidity effects on electrolyte conductivity. WP6 developed testing protocols for EV and aeronautic use cases, coordinated with WP2 and WP7, and supported experimental setups for WP4. WP7 finalized modeling at atomistic, particle, and microstructural levels, linking experimental data to simulations. A physics-based cell-level model was developed and calibrated, awaiting pouch cell data for validation. WP8 demonstrated environmental and economic sustainability of halide-based batteries, achieving high recovery rates for lithium and copper, and over 80% for yttrium. A robust LCA framework was established, with ongoing emissions modeling and plans for a Social LCA. WP9 intensified dissemination through publications and events, and advanced the IPR strategy, identifying 12 Key Exploitation Results, including innovations in halide electrolytes, solid-state cells, and protective layers.
The project has entered Phase II, targeting large-format cell prototype manufacturing. Phase I achievements in material optimization have enabled the development of composite cathodes and solid electrolyte films meeting energy density goals. A key challenge remains: identifying a stable anode–electrolyte interface to ensure reliable cycling performance.
WP1 continued overseeing project monitoring, quality control, and risk management. WP2 advanced testing and validation of HELENA battery cells for automotive and aerospace applications, integrating new aircraft concepts. WP3 focused on improving halide solid electrolytes, developing In-doped Li₃Y₀.₉₇In₀.₀₃Cl₄Br2 and selecting compatible cathodes (NMC622, NMC811). Several strategies were tested to stabilize the lithium–halide interface, but none fully succeeded. WP4 fabricated cell components and optimized extrusion processes, concentrating on 40 mAh monolayer pouch cells. WP5 defined handling conditions for raw materials and assessed humidity effects on electrolyte conductivity. WP6 developed testing protocols for EV and aeronautic use cases, coordinated with WP2 and WP7, and supported experimental setups for WP4. WP7 finalized modeling at atomistic, particle, and microstructural levels, linking experimental data to simulations. A physics-based cell-level model was developed and calibrated, awaiting pouch cell data for validation. WP8 demonstrated environmental and economic sustainability of halide-based batteries, achieving high recovery rates for lithium and copper, and over 80% for yttrium. A robust LCA framework was established, with ongoing emissions modeling and plans for a Social LCA. WP9 intensified dissemination through publications and events, and advanced the IPR strategy, identifying 12 Key Exploitation Results, including innovations in halide electrolytes, solid-state cells, and protective layers.
The project has entered Phase II, targeting large-format cell prototype manufacturing. Phase I achievements in material optimization have enabled the development of composite cathodes and solid electrolyte films meeting energy density goals. A key challenge remains: identifying a stable anode–electrolyte interface to ensure reliable cycling performance.
Outcome 1: Generation 4b Batteries with High Energy and Voltage Stability
HELENA advanced Generation 4b batteries by integrating halide solid electrolytes (2.5 mS/cm conductivity) and optimizing NMC811 B-grade cathodes. Solid electrolyte membranes and cathode laminates for pouch cells were fabricated, with 40 mAh cell designs underway. Multiscale modeling helped understand electrochemical and mechanical behavior. A validated recycling process achieved 92% lithium and nearly 100% copper recovery, promoting vehicle and aircraft electrification.
Outcome 2: Sustainable Li-ion Batteries for Electromobility
Requirements for the automotive and aeronautic sectors were consolidated and formalized in deliverables D2.3 and D6.1. Testing protocols for electrochemical performance, stability, and thermal resistance were defined. Protective layers were explored to stabilize the lithium-metal anode and halide electrolyte interface. Long-term aging tests are planned for future phases.
Outcome 3: Halide-Based Solid-State Cells for Large-Scale Manufacturing
HELENA optimized extrusion parameters for solid electrolyte membranes and cathodes, reducing process time and solvent usage. The development of a new Gen3 halide solid electrolyte improved conductivity and stability. NMC811 B-grade material outperformed NMC622, advancing HELENA’s goal to reduce cell costs below €75/kWh by 2030.
Outcome 4: Battery Recycling for a Lower CO2 Footprint
HELENA achieved a 92% lithium recovery rate and 80% recovery of halide electrolyte components, reducing the need for virgin material. A multi-step recycling process aligned with circular economy principles was developed. A Life Cycle Assessment (LCA) framework supports CO2 reduction efforts, while optimization of nickel and manganese recovery continues.
In conclusion, HELENA's work in RP2 advanced battery performance, sustainability, and manufacturing, supporting the transition to cost-effective, low-emission solutions for electromobility.
HELENA advanced Generation 4b batteries by integrating halide solid electrolytes (2.5 mS/cm conductivity) and optimizing NMC811 B-grade cathodes. Solid electrolyte membranes and cathode laminates for pouch cells were fabricated, with 40 mAh cell designs underway. Multiscale modeling helped understand electrochemical and mechanical behavior. A validated recycling process achieved 92% lithium and nearly 100% copper recovery, promoting vehicle and aircraft electrification.
Outcome 2: Sustainable Li-ion Batteries for Electromobility
Requirements for the automotive and aeronautic sectors were consolidated and formalized in deliverables D2.3 and D6.1. Testing protocols for electrochemical performance, stability, and thermal resistance were defined. Protective layers were explored to stabilize the lithium-metal anode and halide electrolyte interface. Long-term aging tests are planned for future phases.
Outcome 3: Halide-Based Solid-State Cells for Large-Scale Manufacturing
HELENA optimized extrusion parameters for solid electrolyte membranes and cathodes, reducing process time and solvent usage. The development of a new Gen3 halide solid electrolyte improved conductivity and stability. NMC811 B-grade material outperformed NMC622, advancing HELENA’s goal to reduce cell costs below €75/kWh by 2030.
Outcome 4: Battery Recycling for a Lower CO2 Footprint
HELENA achieved a 92% lithium recovery rate and 80% recovery of halide electrolyte components, reducing the need for virgin material. A multi-step recycling process aligned with circular economy principles was developed. A Life Cycle Assessment (LCA) framework supports CO2 reduction efforts, while optimization of nickel and manganese recovery continues.
In conclusion, HELENA's work in RP2 advanced battery performance, sustainability, and manufacturing, supporting the transition to cost-effective, low-emission solutions for electromobility.