Project description
Novel cathode materials for high-voltage, high-energy-density sodium–ion batteries
Sodium–ion batteries (SIBs) are a promising candidate for potential electric storage in grid applications. However, their commercialisation is prevented due to the lack of cathodes with high-output voltage that deliver high-energy density. To deal with these drawbacks, the EU-funded Mixed Anion Cathodes project aims to design a new class of mixed anion compounds called vanadium oxyfluorides that will deliver high specific capacities at higher operating voltage (≥ 3 V). The novel cathode materials will be synthesised through partial fluorination using non-hazardous organic reagents and one-pot microwave-assisted methods. The project’s cathodes will be used to fabricate high-energy-density SIBs for efficient grid storage.
Objective
Sodium-ion batteries (SIBs) are being developed and explored as potential electric storage for the grid applications due to infinite resources for sodium at cheaper price. The major impediment for its commercialization is unavailability of cathodes that possesses high output voltage and delivers high energy density. The state-of-art SIB positive electrodes consist of cathodes with the highest output potential (≤ 3.5 V) exhibiting lower specific capacities (150 mAh/g) while V2O5 cathodes delivered high specific capacity (225 mA/g) at low potential (2.5 V). Therefore, it will beneficial to design cathodes with high output voltage and capacity to build high energy density SIBs.
In this project, the above drawbacks are mitigated by designing a new class of mixed anion compounds, vanadium oxyfluorides as novel cathode materials which are expected to deliver high specific capacities at higher operating voltage (≥ 3 V). These compounds are synthesized by partial fluorination using a non-hazardous organic reagents and novel one-pot microwave assisted methods. The as-prepared materials are characterized to identify their chemical compositions and crystallography using TEM, neutron and synchrotron diffraction techniques. These cathodes are subjected to electrochemical testing in a typical CR2032 coin cells. The solid state NMR is used to study the local structure and Na+ mobility inside cathode host while in-situ XPS provides insight into change in electrode composition at various stages of cycling. The electrochemical pulsed technique and impedance spectroscopy are used to determine diffusion coefficient of Na+ and electrochemical mechanism. The optimized materials will be further tested in a pouch cells resembling a real device. Therefore, this project elucidates the designing of a new class of mixed anions cathodes with high output voltage (≥ 3 V) and deliver high specific capacity (225 mAh/g) for fabricating high energy density SIBs (675 Wh/kg) for efficient grid storage.
Fields of science
- natural scienceschemical scienceselectrochemistry
- natural scienceschemical sciencesinorganic chemistryalkali metals
- natural sciencesearth and related environmental sciencesgeologymineralogycrystallography
- natural scienceschemical sciencesinorganic chemistrytransition metals
- natural sciencesphysical sciencesopticsspectroscopy
Keywords
Programme(s)
Funding Scheme
MSCA-IF - Marie Skłodowska-Curie Individual Fellowships (IF)Coordinator
28040 Madrid
Spain