Lithium iron phosphate batteries — LFP — have become one of the most popular battery chemistries in the world. They are safer than many alternatives, last longer, and cost less to produce. EVs, home energy storage systems, and industrial equipment are increasingly built around them.
But LFP batteries have a problem that rarely makes headlines: they are particularly difficult to recycle.
As LFP batteries reach end of life in growing numbers, Europe needs better ways to recover the materials inside them. Researchers at the National Institute of Chemistry in Ljubljana — part of the CIRCUBATT consortium — are working on exactly that challenge.
Why LFP is hard to recycle
When a lithium-ion battery reaches end of life, recyclers process it into a material called black mass. This is a dark powder containing lithium, iron, phosphate, graphite, and other components. The goal is to separate and recover these materials so they can re-enter the battery supply chain.
For NMC batteries, which contain cobalt and nickel, this process is economically attractive. Those metals command high market prices. As we explored in our article on battery recycling profitability in Europe, the economics of recycling depend heavily on the value of recovered materials.
LFP contains no cobalt and no nickel. Its materials — lithium, iron, and phosphate — are less valuable on the market. And there is a deeper problem too. Conventional hydrometallurgical recycling uses strong inorganic acids to dissolve the black mass. This approach works, but it has significant drawbacks:
- High chemical consumption
- Significant waste generation
- Low selectivity — valuable components like graphite, iron, and phosphate are often lost
- Complex downstream processing, because everything dissolves together in one step
The result is a recycling process that is costly, chemically intensive, and poorly suited to LFP black mass.
A different approach: Deep Eutectic Solvents
Marko Gabrovšek and Blaž Likozar from the National Institute of Chemistry — both CIRCUBATT consortium members — presented a different approach at the Battery 2030+ Annual Conference in Turin in May 2026.
Their research investigates Deep Eutectic Solvents — DES — as an alternative leaching system for LFP black mass recovery.
What is a DES? In simple terms, it is a low-toxicity liquid formed by combining two solid components. One acts as a hydrogen bond donor and the other as a hydrogen bond acceptor. When mixed in the right ratio, these solids form a liquid without requiring harsh chemical conditions. DES are tunable — their properties can be adjusted by changing the components and their ratios — and designed to be reusable, reducing chemical waste across processing cycles.
The cascade leaching concept
The NIC team proposes using DES as part of a sequential cascade process. The goal is to recover each valuable component of LFP black mass separately and selectively.
The process works in two stages:
Stage 1 — Selective lithium extraction: A DES preferentially leaches lithium from the black mass. Iron, phosphate, and graphite are largely left behind, so lithium can be recovered in a relatively pure form. This is a significant improvement over conventional <a href=”https://circubatt-project.eu/battery-recycling-profitability-europe-circular-economy”>acid leaching methods</a>, where everything dissolves together.
Stage 2 — Iron and phosphate recovery: The remaining solid undergoes an oxidative pre-treatment step. This oxidation is critical — the research shows it substantially enhances iron leaching efficiency. After pre-treatment, the material dissolves in a second DES targeting iron and phosphate, leaving graphite as the final solid residue available for separate recovery.
This stepwise approach maximises selectivity, reduces reagent consumption, and enables recovery of multiple valuable fractions using reusable solvent systems.
What the preliminary results show
The research is at an early stage, but the results are promising.
Experiments confirm that DES can effectively dissolve lithium and iron from LFP black mass. Leaching efficiency depends on the DES formulation and on whether the LFP has been pre-treated. The team tested seven different DES formulations across both treated and untreated LFP samples.
Several DES formulations showed preferential lithium extraction over iron from untreated LFP, confirming that selective first-stage leaching is feasible. Complete dissolution of untreated LFP was not achieved. Following oxidative pre-treatment, however, iron leaching efficiency increased significantly. Critically, this oxidation step proved essential for enabling full dissolution of the LFP material.
Three key findings from the research:
- DES enable selective leaching of lithium from LFP black mass
- Oxidation significantly enhances iron leaching efficiency
- A cascade process can recover lithium, iron, phosphate, and graphite sequentially
Why this matters for circular battery value chains
These findings connect directly to one of the central challenges facing Europe’s battery sector: how to build a genuinely circular battery value chain for LFP batteries at scale.
The EU Batteries Regulation introduces minimum recycled content requirements for lithium, cobalt, nickel, and lead. The pressure to recover materials from end-of-life batteries will increase significantly. For LFP batteries — whose market share in Europe is growing rapidly — the absence of effective recycling processes is a gap that needs filling urgently.
A DES-based cascade process offers several advantages over conventional acid leaching. Lower-toxicity chemicals, less waste, more selective material recovery, and reusable solvents all make it a stronger candidate for Europe’s LFP recycling infrastructure. If these advantages can be demonstrated at scale, DES-based recycling could become a key part of a genuinely circular European battery sector.
This work also connects to CIRCUBATT’s broader goal of developing lifecycle-aware battery management strategies. Every stage of a battery’s life — including its end of life — is an opportunity to recover value rather than generate waste. It also reinforces the importance of designing batteries with end-of-life in mind from the very start.
What comes next
The NIC team identifies several priorities for future work:
- Optimising DES formulations for improved selectivity across each stage
- Increasing DES recyclability and fine-tuning process conditions
- Scaling toward an efficient, low-waste recycling strategy for closed-loop recovery of LFP battery materials
The long-term goal is a recycling process that is both greener than conventional acid leaching and commercially viable at industrial scale in Europe.
About CIRCUBATT
CIRCUBATT is a Horizon Europe project (grant no. 101192383) developing integrated solutions for circular battery value chain innovation. The project covers the full battery lifecycle — from sustainable battery design and AI-enhanced lifecycle management to second-life applications and advanced recycling — with the goal of reducing Europe’s reliance on critical raw materials and advancing its circular economy transition.