Batteries based on Calcium: from electrolyte development to full cell proof-of-concept

Project Information

BATCA

Grant agreement ID: 743439

DOI

10.3030/743439

Project closed

EC signature date 17 March 2017

Start date 16 May 2017

End date 15 May 2019

Funded under

• EXCELLENT SCIENCE - Marie Skłodowska-Curie Actions

Total cost

€ 158 121,60

EU contribution

€ 158 121,60

Coordinated by

AGENCIA ESTATAL CONSEJO SUPERIOR DE INVESTIGACIONES CIENTIFICAS
Spain

Periodic Reporting for period 1 - BATCA (Batteries based on Calcium: from electrolyte development to full cell proof-of-concept)

Reporting period: 2017-05-16 to 2019-05-15

Summary of the context and overall objectives of the project

The development of rechargeable batteries based on multivalent cations as charge carriers holds promise of enhanced energy density when compared to single valent ions such as lithium or sodium. Proof-of-concept has been achieved for magnesium batteries with complex electrolyte compositions but an analogous technology based on calcium ion would hold promise for faster reaction kinetics due to its lower polarizing character and enhanced energy density due to its lower reduction potential.

The recently demonstrated feasibility of calcium electrodeposition at moderate temperatures using conventional organic electrolytes constitutes the first step towards proof of concept. The main goal of the present proposal is to achieve proof-ofconcept of a full Ca-ion battery with high energy density through i) optimizing the electrolyte formulation enabling operation at room temperature by minimizing ion pairing and ii) developing a suitable high capacity cathode material.

The proposed research contributed to the study of new classes of electrolyte for calcium cation based batteries with high resilience upon oxidation and low tendency to ion pair formation while at the same time attempting the design of suitable cathode materials enabling calcium ion diffusion and based on suitable redox couples operating at high potential.

The approach behind the scientific project relies on the synergy between the respective expertises of the applicant and the host institution in electrolytes and crystal chemistry of battery materials. This fellowship represents also an excellent opportunity to the researcher for personal and professional development providing him with novel and advanced skills to achieve a status of professional maturity and independent thinking.

Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far

In the project, the molecular interactions within the electrolytes were studied and gave a better understanding of the complexation and ionicity. It is clear that ion-pairing and solvation hinder the kinetic of charges and this effect is larger when going from Na to Ca. It affects a large number of properties of interest such as conductivity, charge transfer and desolvation energies.

Secondly, new cathode materials were synthesized via different routes and the most promising was found to be Ca3MO6. Indeed, it was possible to extract Ca from the structure at room temperature at high potential in laboratory cell prototypes, which will be further investigated.

Finally, a study carried with an energy-cost model developed buy Berg are even more encouraging as the parameters needed (voltage and electrode capacity) to supersede Li-ion are realistically achievable.

Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far)

The aim of the research program developed in BATCA was to go beyond the state-of-the-art of Li-ion technology by designing a Ca metal battery. Even if the final objective of optimizing efficient electrolytes and cathodes for full Ca battery cells, this work paved the way to further improvement.

First, a solid explanation of molecular interaction with electrolytes using sodium has been provided and will be publish in the current of the year. Secondly, now cathode materials have been synthesized using different route and have shown electrochemical activity as Ca2+ could be partially extracted from Ca3MO6 at room temperature. Until now it is the only cathode material which has shown an electrochemical activity at RT.

The electrolyte being the limiting factor, the development of a new stable electrolyte for Ca battery should allow improving performance. Moreover, both the low cost and toxicity of Ca together with an advantageous worldwide repartition makes this potential technology appealing on an industrial viewpoint.

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