EP-4742323-A1 - CORE-SHELL SODIUM-CARBON METATITANATE PARTICLES, PREPARATION METHODS THEREFOR, AND USES THEREOF

Abstract

The present invention relates to sodium-carbon metatitanate core-shell particles, their preparation methods, and their uses as an active anode material for sodium-ion batteries.

Inventors

• ZOIZOU, Yassin
• SIMONIN, Loïc
• MATEI GHIMBEU, Camelia
• BEDA, Adrian

Assignees

• Commissariat à l'Energie Atomique et aux Energies Alternatives
• Centre National de la Recherche Scientifique
• Université de Haute Alsace

Dates

Publication Date

20260513

Application Date

20251107

Claims (12)

1. Particle consisting of or comprising a core (A) consisting of or comprising sodium metatitanate, and, in contact with it, a layer (B) consisting of or comprising carbon, said particle having a specific surface area of less than 20 m².g⁻¹ , the mass of carbon representing from 1 to 25% by mass, relative to the total mass of said particle
2. Particle according to claim 1, the largest dimension of which is less than 15µm, in particular less than 10µm, more particularly less than 9, 8, 7, 6, 5, 4, 3, 2 or 1µm.
3. Particle according to any one of the preceding claims, wherein: - the shell has a thickness between 1 and 100 nm, in particular between 5 and 20, 30 or 40 nm; and/or - the mass of carbon represents between 1 and 10, 11, 12, 13, 14 or 15%, by mass, relative to the total mass of said particle.
4. Particle according to any one of the preceding claims, having a specific surface area less than 15 m².g⁻¹ , in particular less than 10 m².g⁻¹ , in particular less than 9 , 8, 7, 6, 5, 4, 3 or 2 m².g⁻¹ .
5. A particle preparation process according to any one of claims 1 to 4, comprising a step (i) of chemical vapor deposition (CVD) of a layer made of or comprising carbon onto particles made of or comprising sodium metatitanate.
6. A method according to claim 5, wherein step (i) is carried out at a temperature of 500 to 800°C, and/or for 30 minutes to 12 hours, in particular for 1 to 6 hours.
7. A method according to any one of claims 5 to 6, wherein step (i) is carried out under an inert atmosphere, in particular under argon, nitrogen, ammonia, hydrogen sulfide or mixtures thereof, or under vacuum.
8. A method according to any one of claims 5 to 7, wherein step (i) is carried out in the presence of a carbon source, in particular a gaseous carbon source, for example selected from acetylene, ethylene, propylene, methane, and mixtures thereof.
9. A process according to any one of claims 5 to 8, wherein said particles or powder are obtained by hydrothermal synthesis or by solid-phase synthesis.
10. Use of particles according to any one of claims 1 to 4 for the preparation of an anode, in particular a sodium-ion accumulator anode.
11. Anode composition, in particular sodium-ion accumulator anode, comprising as active material particles according to any one of claims 1 to 4, and further comprising at least one conductive agent, in particular up to 5% by mass, and/or at least one binder.
12. Sodium-ion accumulator comprising an anode comprising as active material particles according to any one of claims 1 to 4.

Description

The present invention relates to sodium-carbon metatitanate core-shell particles, their preparation methods, and their uses as an active anode material for sodium-ion batteries. With growing concerns about climate change in recent years, the focus has shifted to transitioning from fossil fuel-based energy to renewable energy sources such as solar and wind power. The intermittency of these sources necessitates energy storage. In this new era of renewable resources, energy storage in the form of stationary batteries is as important as the solar/wind farms themselves, and their performance as an integrated system generally determines their market success. In this regard, the cost of these grid-tied batteries is, and will continue to be, the most critical factor. Lithium-ion batteries (LIBs), which represent the state of the art and easily outperform other traditional battery technologies, are not suitable for grid-tied applications due to the limited availability of lithium reserves. Furthermore, concerns about the future price of lithium, particularly as demand increases in the future due to the rapid escalation of demand for lithium-ion batteries for applications such as electric vehicles, necessitate, in order to limit them, an alternative battery technology that does not depend on lithium, while having performance comparable to that of lithium-ion batteries. In this regard, sodium-ion batteries (NIBs) are very well suited since they operate on the same principle as lithium-ion batteries (LIBs), and recent reports suggest they can rival or even surpass LIBs in performance. The shift to NIBs would make sense since sodium is very abundant, and a sodium-based battery technology would therefore be much cheaper than a lithium-based one. NIBs, like LIBs, require a cathode material capable of inserting/disinserting sodium ions at a high potential, and an anode material capable of doing the same at low potentials. In this context, sodium metatitanate ( Na2Ti3O7 ) is a promising anode material, as it has several significant advantages for the preparation of active anode materials in sodium-ion batteries. First, Na2Ti3O7 is the insertion electrode material with the lowest described sodium ion insertion potential, with a plateau region around 0.3 V, with an average discharge voltage in the range ( 0.01-2.5 V vs. Na+ / Na). Sodium metatitanate also offers excellent chemical and thermal stability. This stability is crucial for sodium-ion batteries, as it allows the anodes to operate efficiently over a wide range of temperatures and chemical conditions, thus increasing battery durability and reliability. Furthermore, this material possesses a good theoretical capacity for storing sodium ions. The crystalline structure of sodium metatitanate allows for efficient insertion and extraction of sodium ions, resulting in a high energy density. This is essential for improving the range of devices powered by these batteries, such as electric vehicles and renewable energy storage systems. Furthermore, sodium metatitanate is abundant and inexpensive. First, compared to lithium, and as mentioned above, sodium is much more readily available in the Earth's crust and less expensive to extract and process. This abundance and low cost can reduce the production costs of sodium-ion batteries, making this technology more accessible and sustainable. And sodium metatitanate itself can be synthesized easily and on a large scale using a solid-state method. Finally, sodium metatitanate has a high density (e.g. tapped) compared to carbon, thus allowing for an increase in volumetric capacity. Coating sodium metatitanate with carbon offers additional advantages. Carbon coatings improve the electrical conductivity of the anode, resulting in better overall battery performance. Furthermore, carbon can protect the sodium metatitanate from undesirable reactions with the electrolyte, thereby increasing the stability and lifespan of the anode. Carbon coatings can also improve the mechanical strength of the anode, reducing the risk of structural degradation during charge and discharge cycles. However, sodium metatitanate typically has low initial coulombic efficiency in the first cycle and the electrode requires a high amount of Super P, usually tested with 20% Super P, as a conductive additive. Besides this low coulombic efficiency, such a quantity of additive has the effect of increasing the proportion of inactive material in a detrimental way, both from an economic and industrial point of view. One objective of the invention is therefore the development of an active anode material for a sodium-ion battery that allows: improved initial capacity and coulombic efficiency, improved cycling performance, particularly with regard to the initial coulombic efficiency of the first cycle, and to improve battery life. Another objective of the invention is to design such a material using a robust, repeatable process, enabling in particular the outer layer of the inv