DS0205 - Stockage, gestion et intégration dans les réseaux des énergies

Catalytic Effect Engineering by Nanostructures: next-generation anode-Materials for lithium-ion batteries – CEENEMA

An original process, based on nanosecond-pulsed discharges in dielectric liquids coupled to laser post-treatment depending on the expected results, has been proposed to develop metastable particles under equilibrium conditions while meeting requirements for users’ safety and for environment respect. Nanoparticles well controlled both chemically and structurally with narrow size distributions were produced in liquid nitrogen under micrometric inter-electrode space conditions. The production rate is 100 to 1000 times faster than laser ablation in liquids. Above all, the chemical composition of nanoparticles is particularly interesting because it is possible to combine elements that do not form alloys at thermodynamic equilibrium. For example, it has been possible to create Cu-Ag nanoparticles containing up to 40% silver, which is totally impossible at equilibrium. Other systems (Cd-Ag, Co-Ni or Cu-Ag) have also been studied to better understand the mechanisms behind the formation of these non-equilibrium alloys.

We have been able to produce SnO2 and GeO2 nanoparticles with controlled size distributions and extremely high synthesis rates, of the order of 100 mg / h, by discharges into deionized water.
A whole series of other nanoparticles have also been produced among which PbO2, Bi2O3, Pt, ZnO, CuO, CdO, etc.
Cu-Ag alloy nanoparticles (NPs) have been synthesized from particles of pure Cu and Ag using consecutively two non-equilibrium processes based on plasma and lasers in liquids. The plasma process reduces the size of the initial particles down to nanometric size at which the laser fluence is sufficient to melt them, making alloying possible. Measurements at macroscopic (optical absorption of the solution), microscopic (luminescence of individual NPs) and nanoscopic (electron microscopy) scales confirm the alloying of NPs and their homogenization in size and composition. This has noticeable effect on the final colloidal solution that absorbs yellow-orange light (550 - 600 nm) after laser treatment. The possibility to quench the as-formed liquid alloy leads to phase compositions that are not compliant with the phase diagram. With a synthesis rate of 360 mg/h, this process opens up interesting perspectives for non-equilibrium nano-metallurgy of functional NPs.

The development of this study now makes it possible to generalize the concept of out of equilibrium nanoparticles to catalysis and optics.

6 articles all acknowledging the ANR for its support to the CEENEMA project have been accepted in peer-reviewed journals and two articles are in preparation. We note the production of a review article published in «Applied Physics Reviews - impact factor: 12.75 «

Submission summary

Due to the uneven production of renewable energy, it is impossible to use these energy sources for transportation. The proposed research in the CEENEMA project will bridge the gap between renewable energy and electrical devices. Light, high-capacity, high-powered and safe Lithium Ion Batteries (LIBs) can power the needs of electric vehicles. Nanostructure-based energy storage offers high opportunities. In that sense, the performance of anode material can increase by making nanocomposites. Furthermore, there is an urgency to replace graphite anodes which limit today the power density of LIB. Our goal is two-fold to reach industrial transfer within a short period of time:
1°) In a model SnO2 based anode material, the lithium storage mechanism can be described by a first irreversible reaction where Li+ ions are oxidized by SnO2 into Li2O, which forms metallic Sn, followed by an alloying-dealloying reaction between Sn and Li+. In this case, one of the most efficient ways to increase the initial Coulombic Efficiency (CE) is to convert the metal Sn into SnO2 and promote the decomposition of Li2O during the charge process (vs. Li metal). This reaction can greatly improve the reversible capacity by increasing the theoretical lithium storage capacity from 4.4 Li+ per SnO2 (782 mAh/g) to 8.4 Li+ (1493 mAh/g). One aim of this project is to investigate the mechanism and conditions for catalytic effect to promote the reverse reaction of the allegedly irreversible first reaction during the process.
Thanks to this model system, we plan to use SnO2/GeO2-graphene oxide nanocomposites as a platform for the catalytic mechanism study. Based on the SnO2/Ge or SnO2/GeO2system, we shall design and synthesize nanostructures that will enable high initial CE and ultra-stable high performance rate capability anode materials as well as further improve the battery efficiency, especially the stability at large current densities. In addition, the content proportion of SnO2, GeO2 and graphene will be optimized for accurate cost estimation of this process. Other possible catalysts including CuO, Co3O4, Fe2O3, MnO2, NiO, Au, Pt, etc. will be tested.
Our joint research also targets at an innovative approach of incorporating hybrid-nanostructures with catalytic effect engineering (i.e. promote irreversible reaction) and improve the performance of anode materials beyond theoretical capacity. The design of metal oxide hybrid nanostructures will provide better understanding for metal oxide catalytic engineering.
2°) This approach of a new type will be declined in an enlarged vision which is market-oriented since high-rate production of nanoparticles with perfectly-designed features is mandatory to produce LIBs at low cost. An original process, based on discharges in dielectric liquids, is foreseen as the best answer to this issue in terms of innocuousness, environmentally-friendly processing and energy-saving. Chemically and structurally well-controlled nanoparticles with narrow size-distribution between 2 and 20 nm will be produced by discharges in water or liquid nitrogen in micrometric interelectrode gap distance. The production rate will be about 100 to 1000 times faster than nanosecond laser ablation in liquids.
Surface functionalization of nanoparticles will be ensured by different means like adding acids (HCl or HNO3, e.g.) to water during discharges or microplasma jet at atmospheric pressure in contact with water, a new process discovered recently for surface engineering of nanomaterials. Coupled with plasma diagnostics like time-resolved optical emission spectroscopy and picosecond iCCD imaging, the most advanced materials characterizations will be used to optimize the nanoparticles design and properties.
Our approach is unique and promising for low-cost high-efficient LIB applications. The proposed topics should generate capability and manpower development for Singapore and France.

Project coordination

Thierry BELMONTE (Institut Jean Lamour)

The author of this summary is the project coordinator, who is responsible for the content of this summary. The ANR declines any responsibility as for its contents.

Partner

IJL Institut Jean Lamour
SUTD Singapore University of Technology and Design

Help of the ANR 233,792 euros
Beginning and duration of the scientific project: December 2015 - 36 Months

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