Prof. Dr. Volker Presser

Lithium-ion batteries play a crucial role in powering electric vehicles and portable electronics, making them indispensable in modern technology and driving a significant increase in global lithium demand. With more and more batteries reaching their end of life and the challenges of lithium extraction, including rising prices, geopolitical constraints, and environmental concerns, the efficient recovery of lithium from spent battery cells is crucial for sustainable battery recycling. While state-of-the-art battery recycling focuses mainly on pyro- and hydrometallurgical methods, electrochemical recycling methods can be an environmentally friendly, energy-efficient, and cost-effective alternative. This study optimizes an energy-efficient electrochemical method for selective LiCl extraction from leaching solutions derived from cathode materials of a typical battery cell format (lithium cobalt oxide (LCO)). This places our electrochemical separation within the hydrometallurgical processing of spent battery materials (black mass) and prior to subsequent lithium refining steps. Applying carbon-coated lithium iron phosphate (LFP) electrodes for selective lithium recovery yielded an average uptake capacity of 11.4 mgLi gLFP/C-1 over 300 cycles, maintaining a significant discharge capacity (30 mAh g-1) after 500 cycles.

In technologies for PFAS removal, one of the biggest challenges is combining high adsorption capacity with excellent regeneration capabilities. In recent years, metallopolymer-based materials have shown promising potential in both aspects. In this work, we present two convenient ways to functionalize organic microparticles with charged, functional moieties (cobaltocenium), either through a one-pot reaction via siloxane-condensation or by straightforward ring-opening reaction of epoxides. After characterization of the novel adsorbent materials by state-of-the-art analytics to verify the successful functionalization, their performance for PFAS adsorption and regeneration was investigated. To gain insight into the adsorption mechanism, experiments were first conducted at low concentrations (20 μg L−1) and in equilibrium, showing adsorption for both materials of up to 97 % for PFOA and PFOS. Furthermore, an increase in adsorption within an ionic matrix of commercial drinking water and an adsorbent preference at different pH values was demonstrated. Analysis of the influence of the concentration indicates multilayer adsorption beyond simple ion-paring, best described by a Brunauer-Emmett-Teller mechanism. Moreover, utilizing a straightforward column setup, the total PFOA capacity is analyzed, revealing a 4–5-fold increase upon functionalization, leading to 215 mg g−1 and 296 mg g−1 PFOA adsorption. Overall, column-based adsorption experiments showed promising results at low (20 μg L−1) and medium (2.25 mg L−1) PFAS concentrations. Finally, reusability and regeneration studies further revealed an excellent desorption performance upon multiple cycles and PFAS elution of up to 88 ± 4 %. © 2025 The Author(s)

The energy transition and the intermittent characteristic of renewable energy sources highlight the importance of materials research for energy storage systems. Hexacyanometalates (HCM) are promising candidates in energy storage systems due to their structure, capability of intercalating/extracting ions during the redox process, and the variety of synthesis techniques available. Among HCMs, nickel hexacyanoferrate (NiHCF) gains attention due to its long-life cycle and promising application in aqueous systems. Combining the properties of NiHCF along with freestanding films based on reduced graphene oxide (rGO) and polyaniline (PAni) offers a promising application in aqueous batteries as it includes both the electroactive material and the current collector in a single electrode. Herein, freestanding electrodes based on rGO/PAni/NiHCF are synthesized through the electrodeposition of NiHCF over rGO/PAni films, enabling control of the amount of NiHCF nanoparticles and the freestanding film thickness. Thinner electrodes achieve specific capacity values of 83 mAh g−1 at the current density of 50 mA g−1 in a three-electrode system, a specific capacity close to 61 mAh g−1 at the current density of 10 mA g−1 in a coin-cell system, approaching the theoretical capacity of NiHCF.

With rising demand for lithium-ion batteries, efficient recycling is crucial. While conventional methods face cost and environmental challenges, electrochemical recovery offers a sustainable and energy-efficient alternative. In this study, we investigate the electrochemical recovery of lithium-ions from spent lithium iron phosphate batteries using carbon-coated lithium iron phosphate electrodes, with a focus on the influence of pH adjustment and competing ion effects. Our results demonstrate that NaOH-adjusted electrolytes provide the highest lithium-ion recovery efficiency, with an average removal capacity of 18 mgLi gLFP−1 over 50 cycles. However, prolonged cycling leads to capacity fading, particularly in the presence of competing cations such as Na+ and K+, which impact lithium selectivity and electrode stability. These findings underscore the importance of optimizing electrolyte conditions and electrode materials to enhance long-term performance. Future research should explore alternative pH control strategies and scalable process designs to facilitate industrial implementation. Advancing electrochemical lithium-ion recovery aligns with broader sustainability goals, offering a viable route toward circular battery recycling and reduced environmental impact.

Lithium–sulfur batteries (Li–S), controlled by the sulfur cathode’s conversion reaction, are a promising technology due to their high theoretical capacities and the sustainability of sulfur. In contrast to commercially available lithium-ion cathodes, the Li–S system still suffers from unstable cycling performance due to the diffusion of soluble polysulfides out of the cathode. This study explored sulfur cathodes with varying pore sizes, mainly in the micropore regime (<2 nm). We conducted the work using carbonate-based and ether-based electrolytes to investigate the impact of the cathode/solid electrolyte interphase on the cycling performance of the battery. By infiltrating the carbon with different C/S ratios, we found that the maximum sulfur infiltration attained was 61 mass % with a C/S ratio of 1:1.5. The best sulfur utilization and cycling performance were achieved with carbonate electrolyte and 50 mass % S in carbon with a specific surface area of 2210 m2/g and a total pore volume of 1.20 cm3/g. Our findings emphasize the importance of designing cathodes with optimized pore structures to balance sulfur accommodation, minimize sulfur dissolution, and mitigate capacity degradation.

We report the successful synthesis of nanocomposites between the MXene Ti3C2Tx and polyaniline (PAni), achieved via an innovative approach starting from the intercalation of anilinium ions into non-exfoliated Ti3C2Tx, and followed by a liquid/liquid interfacial polymerization. This approach produces transparent films with beneficial optical quality. The spectroscopic analysis confirmed the formation of PAni in its conductive form, emeraldine salt. The absence of TiO2 bands in the Raman spectra indicated that the organic polymer protected Ti3C2Tx from degradation, even in acidic media. Electrochemical characterization revealed that the nanocomposites exhibited promising performance as supercapacitors, with specific capacity dependent on the amount of polymer. The combination of the conductive Ti3C2Tx and the redox activity of PAni, as well as the specific nanoarchitecture in which the materials are organized, significantly improved the electrochemical response, facilitating ion diffusion. These transparent films demonstrated specific capacity values up to 89 mAh g-1 at 0.1 mAh g-1, with the potential for further enhancement through current collector optimization, positioning them as strong candidates for miniaturized energy storage applications and transparent devices.

The synthesis of an amphiphilic three-arm block copolymer (AB)3-BCP, which consists of poly(methyl methacrylate) (PMMA) and poly(butyl methacrylate) (PBMA) in the hydrophobic inner block, is reported. The hydrophilic block segment is based on poly(2-hydroxyethyl methacrylate) (PHEMA) originating from 2-(trimethylsiloxyl)ethyl methacrylate (HEMA-TMS). The preparation is carried out in two steps using a core-first approach. Using atom transfer radical polymerization (ATRP) as a controlled polymerization technique, three (AB)3-BPCs with HEMA contents of 15 to 38 mol−1 % are prepared, applying different reaction conditions. Porous structures are generated from these BCPs by applying a self-assembly and nonsolvent-induced phase separation (SNIPS) protocol. Complex surface structures are observed using scanning electron microscopy (SEM). Bulk morphologies are investigated for a better understanding of the underlying self-assembly. For PHEMA-rich (AB)3-BCPs, non-regular lamellar microphases are observed in transmission electron microscopy (TEM) and confirmed by small-angle X-ray scattering (SAXS). The porous structures and their expected swelling characteristics are analyzed using atomic force microscopy (AFM) in air and water. Time-resolved measurements in water indicate a rapid swelling after immersion into the water bath. The present study paves the way for exciting porous materials based on the herein synthesized amphiphilic three-arm block copolymers useful for applications as absorber materials and coatings.

The demand for lithium production has seen a significant rise, with the growing electric vehicle and stationary battery markets requiring further development of sustainable and scalable extraction methods. Direct lithium extraction technologies have been developed to address potential shortages, with adsorption emerging as a key method due to its efficiency and low environmental impact. Given that Al(OH)3 is already utilized as an adsorbent in various industrial applications, the practical importance of Al-based alternative systems for lithium ion extraction is increasing, yet lithium ion recovery requires harsh chemicals. In this study, we report a novel lithium extraction method combining chemical adsorption and electrochemical release using a synthesized aluminum layered double hydroxide (Al-LDH) material, developed under mild reaction conditions. The performance of the Al-LDH electrode was evaluated against a commercial Al(OH)3 adsorbent. Comprehensive characterization using techniques such as X-ray diffraction, Fourier-transform infrared spectroscopy, and scanning electron microscopy revealed detailed insights into the crystalline structure, particle size distribution, and surface morphology of the materials. The Al-LDH electrode exhibited a lithium ion adsorption capacity, achieving an average chemical uptake of lithium ions of 57.6 mg/g. In contrast, lithium-ion uptake capacity for Al(OH)3 was 1.0 mg/g over 15 cycles. Notably, this method operates under pH-neutral conditions, eliminating the need for harsh acidic or basic eluents. As a result, it prevents structural degradation and minimizes secondary pollution for potential future applications of lithium-ion recovery. The material’s layered structure selectively allowed lithium ion intake while blocking sodium ions, demonstrating its high selectivity and utility in lithium ion recovery processes. The integration of pH-neutral regeneration and high selectivity shows that Al-LDH electrodes as viable candidates for next-generation, green lithium extraction technologies.

This work presents a novel approach to enhance the specific energy of supercapacitors by developing Bi2O3/Mn3O4/Mn2AlO4(OV)/rGO multiphase oxygen vacancy heterostructures via dealloying and hydrothermal self-growth strategy. The synergy between reduced graphene oxide (rGO) heterostructures and oxygen vacancy defects generates an internal polarized electric field that accelerates ion transport and enhances electrochemical response through an interconnected conductive network. This innovation extends the operating voltage from 0.6 to 0.8 V, significantly improving material energy storage. An asymmetric supercapacitor assembled with Bi2O3/Mn3O4/Mn2AlO4(OV)/rGO//rGO delivers a specific energy of 333 Wh kg−1 and a specific power of 6.3 kW kg−1 at a cell voltage of 4.9 V. At the highest specific power (31 kW kg−1), the specific energy remains at 204 Wh kg−1. Density functional theory (DFT) simulations further validate that the synergy of oxygen vacancies and heterostructures enhances conductivity, narrows the bandgap, and improves surface properties, unveiling novel theoretical perspectives on ion transport dynamics within oxygen vacancy heterostructures.

This study presents a novel approach to developing high-performance lithium-ion battery electrodes by loading titania-carbon hybrid spherogels with sulfur. The resulting hybrid materials combine high charge storage capacity, electrical conductivity, and core-shell morphology, enabling the development of next-generation battery electrodes. We obtained homogeneous carbon spheres caging crystalline titania particles and sulfur using a template-assisted sol-gel route and carefully treated the titania-loaded carbon spherogels with hydrogen sulfide. The carbon shells maintain their microporous hollow sphere morphology, allowing for efficient sulfur deposition while protecting the titania crystals. By adjusting the sulfur impregnation of the carbon sphere and varying the titania loading, we achieved excellent lithium storage properties by successfully cycling encapsulated sulfur in the sphere while benefiting from the lithiation of titania particles. Without adding a conductive component, the optimized material provided after 150 cycles at a specific current of 250 mA g–1 a specific capacity of 825 mAh g–1 with a Coulombic efficiency of 98%.