Understanding Lithium Recovery Mechanisms through the Application of Electrochemical Pumping on Battery Leachates
The economical, environmental and geopolitical context recently pushed Europe to issue a regulation on battery recycling. By 2031, 80% of lithium in batteries should be recovered. In this context, CEA is interested in Electrochemical Lithium-Ion Pumping (ELIP): this process uses battery electrodes to selectively insert and disinsert lithium, allowing to extract it from a complex solution. Unlike more common lithium recovery processes, ELIP allies a high selectivity towards lithium, does not require the use of toxic chemicals during the process and offers the possibility to be used in a continuous flow mode, practical for industrial applications. A first PhD work on the subject, in our team, evidenced for the relevance of such a process for the separation of lithium from other alkali cations (sodium and potassium). Real battery leachates are however more complex and can include transition metal cations and organic species besides alkaline cations. The proposed PhD subject has the aim to precisely understand the effect of these solutions on the ELIP process in order to choose the best position in the recycling loop (upstream or downstream), and to adapt to adverse effects encountered in such conditions. The impact of the other species present in solution will be evaluated on selectivity, efficiency and durability at different scales: material, electrode and membrane. Chemical (ICP-AES, EDX), structural (XRD) and morphological (SEM, TEM) characterizations will be correlated with electrochemical results in order to identify side reactions and species which impact the most the performances. Based on these results, the PhD student will have to test different improvement protocols (additive incorporation, pH control, change of the electrochemical method, etc...) and to understand the physico-chemical reasons governing these improvements. The PhD work will allow to propose a thoughtful integration of the ELIP process in conventional battery recycling steps, as well as highlighting the relevance, or not, of such a process for lithium extraction from real leachates.
Advancing All-Solid-State Microbatteries: Interface Stabilization and Degradation Mitigation for Long-Term Reliability
This PhD project focuses on advancing all-solid-state microbatteries for miniaturized energy storage applications, such as wearable electronics, IoT systems, and implantable medical technologies. The research aims to stabilize and mitigate degradation at the electrode/electrolyte interfaces, which are critical bottlenecks in solid-state microbattery performance. The project involves two main research axes: (1) the study and optimization of ultrathin films (sub-nanometer to nanometer scale deposited by ALD) for engineering the interfaces in LiCoO2/LiPON/Li stacks, and (2) a fundamental investigation of the mechanisms responsible for interface degradation. The study will involve the fabrication and characterization of partial and complete stacks using techniques like cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), X-ray diffraction (XRD), and scanning electron microscopy (SEM). The incorporation of alloying metals (e.g., Ag, Au) between the buffer layer and lithium will also be explored to enhance lithium-metal interface stability. The expected outcomes include an optimized microbattery stack capable of exceeding 1,000 cycles with minimal increase in interfacial resistance and a comprehensive framework describing degradation mechanisms and buffer layer effects.
Exploring the Strategic Benefits of 0V Storage for Na-ion Batteries
Recently deployed on a commercial scale, the Na-ion battery technology demonstrates excellent behaviour during medium or long-term storage at zero voltage. This characteristic offers numerous safety advantages during the transport, assembly and storage of cells and modules, as well as during emergency shutdowns in the event of external issues. But are there no consequences for battery performance?
This research project aims to study and better understand the electrochemical mechanisms at play when the potential difference across the terminals is maintained at 0 V.
Initially, advanced dynamic characterisation techniques will be used to analyse and compare the electrochemical, thermal and mechanical properties of battery materials. The results will enrich calendar and cycling ageing models at the cell scale, thereby improving their accuracy and reliability. Subsequently, tests will be conducted on mini-battery modules assembled in various electrical architectures to study cell behaviour during cycling and ageing, particularly in response to the application of negative voltage. Specific battery management system (BMS) solutions could then be proposed to address these issues.
The scientific approach will involve implementing advanced characterisation and instrumentation techniques, conducting ageing and safety tests to identify mechanisms, and developing ageing models. This approach will draw on the expertise and testing facilities of CEA-Liten at the Bourget du Lac site in Savoie.
Influence of battery system disassemblability on their environmental impacts
With the rise of electric mobility and Energy storage, the demand for batteries is rapidely increasing. But this growth raises a crucial question: how can we design batteries that are both high-performing, durable, and more environmentaly friendly ?
Without focusing on cell Chemistry, one promising approach lies in disassembly-oriented designs: making battery packs easier to disassemble could facilitate their repair, reuse, or recycling. However, a more easily dismantled design may also increase its mass or reduce the system's reliability, potentially affecting its overall lifetime.
This PhD aims to tackle this challenge by developing an analytical method to link the design of dismountable battery systems with their actual environmental impacts, while explicitly accounting for reliability aspects.
The PhD candidate will assess the ease of disassembly of different battery systems, quantify the environmental gains and losses compared to conventional designs, and help develop a decision-support tool to guide design choices. The proposed research will involve, among other tasks, Life Cycle Assessment (LCA) modelling coupled with battery performance and ageing models, as well as failure probabilities analysis.
This project takes place in a technological context driven by the growing need for resource circularity, the automation of disassembly processes, and the implementation of new European regulations on batteries. If offers a unique opportunity to contribute to the design of the next generation of sustainable battery systems.
Innovative techniques for evaluating critical steps and limiting factors for batteries formation
The battery manufacturing sector in Europe is currently experiencing strong growth. The electrical formation step that follows battery assembly and precedes delivery has received little academic attention, despite being crucial for battery performance (lifespan, internal resistance, defects, etc.). It is an essential time-consuming and costly step in the process (>30% of the cell manufacturing cost, and 25% of the equipment cost in a Gigafactory) that would greatly benefit from optimization.
In this thesis, we propose studying battery formation using innovative, complementary, operando non-intrusive techniques. The goal is to identify the limiting mechanisms of the electrolyte impregnation step (filling electrode pores) and of the initial charge. The candidate will implement experimental methods to monitor and analyze these mechanisms. He will also establish a methodology and protocols for studying these steps, combining electrochemical measurements with non-intrusive physical characterizations under operating conditions. The research will focus on optimizing formation time and quality control during this stage.
Fast charging of lithium-ion batteries : Study of the lithium plating phenomenon using operando NMR
The focus of the thesis is the fast-charging process of lithium-ion batteries and, more specifically, the phenomenon of lithium plating, which will be studied using operando NMR. The target application is electric mobility. The objective of the thesis is to study the dynamics of lithium insertion and lithium metal deposition at the graphite or graphite/silicon-based negative electrode in order to understand the mechanisms leading to plating formation.
Operando NMR is an ideal technique for this study because it offers the unique possibility of simultaneously tracking the signals of the lithiated graphite phases and of deposited lithium during the electrochemical processes. The coupling of electrochemistry and operando NMR will allow us to determine the onset of plating, i.e. the potential of the negative electrode at which deposition begins, and the kinetics of lithium metal deposition and reinsertion at different temperatures and different charging current regimes. We will study Li-ion batteries with a pure graphite negative electrode, but also with graphite-silicon electrodes, in order to investigate the impact of silicon on this phenomenon. The data obtained on the onset mechanisms and the kinetics of lithium metal deposition and reinsertion will be used in a multiphysics model that has already been developed in the laboratory to improve the prediction of plating onset. We will then be able to evaluate the chargeability gains on an NMC 811 // Gr+Si system incorporating optimized electrodes and propose innovative charging protocols.
Exploration of VACNTs in Anode-less Batteries: Mechanism and Cell Optimization
Anode-less or anode-free batteries are getting increasing attention owing to their excellent energy density, cost efficiency, and ease of process upscaling. Exploring anode-less battery will offer a breakthrough in energy storage devices by using the lithium reserve already present in the NMC cathode to reversibly cycle after an initial formation process, which will reduce the overall thickness, processing steps, and cost of materials, and provide excellent energy density. Vertically aligned CNTs (VACNTs) on metal substrates can be an interesting choice for this application due to their low thickness, reproducible synthesis process, and uniform surface properties, which have already proven their applicability in supercapacitors. In this PhD project, we will investigate their newer avenue of applications- anode-less batteries, where VACNTs act as the lithium or sodium plating substrate. We will study the electrochemistry of VACNT in lithium anode-less batteries (in liquid and solid electrolytes) and in sodium anode-less batteries in a liquid electrolyte. The PhD student will work on the synthesis optimizations of VACNT to tune the thickness and density to match their electrochemistry. Post-cycling studies (Raman and SEM) will be carried out to study the effect of cycling and the electrolytes on the VACNT layers. The project aims to explore the possibility of the application of VACNTs in various energy storage systems, which can open up new application possibilities and valorization