TOPIC #8
Exploring new layered oxides compounds as positive electrode materials for Li-ion battery applications
Research area: Advanced Methods, New Materials & Electrolytes
Keywords: Positive-electrode; Oxides; Li- and Na-ion; Metastability; Crystal chemistry
Supervising team: Marie GUIGNARD(UB) & Laurent CASTRO (Toyota)
Abstract
O3-type lithium layered transition-metal oxides with the formula Li₁₊ₓM₁₋ₓO₂ (0 ≤ x < 1/3, M is a mixture of transition metals and alkaline ions) are promising positive-electrode materials for lithium-ion batteries because of their fast lithium intercalation kinetics. However, during cycling, transition-metal ions can migrate into the lithium layers, especially near particle surfaces. This migration increases resistivity and decreases reversible capacity, limiting the practical performance of these materials. One strategy to mitigate these issues is to develop layered oxides with alternative oxygen-stacking sequences, such as O2- or O6-type structures. In these configurations, face-sharing between LiO₆ and MO₆ octahedra increases interlayer coulombic repulsion, making cation migration energetically unfavorable.
tPrevious work at ICMCB/TME has established robust synthesis of O2- and O6-type materials via ion exchange from sodium analogues, elucidated their atomic structures, quantified stacking faults, and demonstrated stable cycling over hundreds of cycles. Yet, the origin of stacking faults and their impact on long-term electrochemical behavior remain poorly understood. This PhD project aims to address these gaps through four complementary approaches: predicting stacking-fault energetics using DFT calculations; synthesizing Li₁₊ₓM₁₋ₓO₂ compositions with controlled fault densities; evaluating their electrochemical performance; and performing advanced structural characterization (XRD, PDF, HRTEM, including operando). The overall objective is to clarify how stacking faults arise and influence battery performance, ultimately guiding the design of improved layered oxide cathodes.
Interest for the student
Expected mobility:The Ph.D. student will have the opportunity to participate in at least two conferences, one in France and one abroad. He or she will have the opportunity to meet leading international scientists working in the field of battery research. The student may also join specific training programs proposed by DESTINY2, or other ones including theoretical training, such as crystallography schools, and practical training, such as electrode formulation training.
In addition to attending national and international conferences and schools, the PhD student will collaborate with an industrial partner for several periods of secondment. These periods (four months total) will take place at the Toyota Motor Europe (TME) Technical Center in Zaventem, Belgium. The R&D Material Engineering (ME) division conducts cutting-edge research for the Toyota group in Europe in the fields of batteries, fuel cells, catalysts, solar cells, materials modelling, and advanced analysis. For over 15 years, the ICMCB and TME have collaborated closely to design new electrode materials for batteries. Therefore, the PhD candidate will benefit from balanced co-supervision by academic and industrial partners.
Career opportunities: The student will benefit from the network of academic and industrial collaborations that the ICMCB has established over many years. They will have the opportunity to meet renowned scientists at the scientific conferences that the ICMCB plans to organise during their PhD. This will enable the PhD student to identify potential supervisors for a postdoctoral position. ICMCB alumni also form an important network within companies that work in the field of electrochemical energy storage. Therefore, the student will be able to benefit from the support of this community if they are interested in pursuing an industrial career.
