Blended positive electrodes in solid-state batteries: Effect of the electrode fabrication process on electrochemistry
The development of cost-effective, high-energy-density solid-state batteries (SSBs) is essential for the large-scale adoption of next-generation energy storage technologies. Among various cathode candidates, LiFePO4 (LFP) and LiFe1??Mn?PO4 (LFMP) offer safety and cost advantages but suffer from low working voltages and limited kinetics compared to Ni-rich layered oxides such as LiNi0.85Mn0.05Co0.1O2 (NMC85). To balance energy density, rate capability, and stability, this PhD project aims to develop blended cathodes combining LFMP and NMC85 in optimized ratios for solid-state configurations employing sulfide electrolytes (Li6PS5Cl). We will investigate how fabrication methods- including slurry-based electrode processing and binder-solvent optimization- affect the electrochemical and structural performance. In-depth operando and in situ characterizations (XRD, Raman, and NMR) will be conducted to elucidate lithium diffusion, phase transition mechanisms, and redox behavior within the blended systems. Electrochemical impedance spectroscopy (EIS) and titration methods will quantify lithium kinetics across various states of charge. By correlating processing conditions, microstructure, and electrochemical behavior, this research seeks to identify optimal cathode compositions and manufacturing strategies for scalable, high-performance SSBs. Ultimately, the project aims to deliver a comprehensive understanding of structure–property relationships in blended cathodes, paving the way for practical solid-state battery technologies with enhanced safety, stability, and cost efficiency.
Synthesis of organic aerogels from polydicyclopentadiene derivatives
The study of inertial confinement fusion of the deuterium + tritium (DT) mixture has long been a research focus at the CEA. Experiments related to this topic, carried out within the Laser Mégajoule (LMJ) facility, require the use of materials with specific properties. This includes, among others, polymer foams (organic aerogels) used as pre-ignition targets. Such materials must combine very low density with sufficient mechanical strength to be compatible with the preparation process employed.
In this context, the objective is to develop CHx polymeric aerogels based on polydicyclopentadiene (pDCPD) and other polymers derived from ring-opening metathesis polymerization (ROMP), in order to produce materials that are (i) of low apparent density (target value in the project: below 50 mg/cc), (ii) homogeneous, (iii) exhibiting fine (open) nano-porosity, and (iv) machinable.
The proposed PhD work would focus on three main areas:
1. The synthesis of new (co-)monomers
2. The preparation of organic aerogels
3. The exploitation of data using AI (opportunity)
Rheology and Conduction of Functional Polymers for Embedded Electronics in 3D/4D Additive Manufacturing
This PhD project, conducted on the MAPP platform (CEA-Metz), focuses on the development of additive manufacturing (3D/4D) processes for the integration of smart materials. The aim is to overcome the limitations of traditional planar electronic architectures (PCBs, wafers) integration by enabling the direct-to-shape printing of electronic functions within 3D parts performed by Fused Deposition Modeling and Paste Extrusion Modeling. The research will address functional conductive polymers, composed of an organic matrix and metallic particles, whose conduction mechanisms (direct contact, tunneling effect, ionic conduction) are governed by the percolation threshold. The study will investigate the processing of these materials, their rheological and electrical behavior, and the exploitation of their resistive, piezoresistive and piezoelectric properties to design novel sensor (3D) and actuator (4D) functions. The doctoral candidate will benefit from advanced characterization facilities and the guidance of a multidisciplinary team with expertise in additive manufacturing, materials science, and microelectronics.