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Nanoencapsulation for Energy Storage and Controlled Release

Periodic Reporting for period 4 - ENERCAPSULE (Nanoencapsulation for Energy Storage and Controlled Release)

Reporting period: 2020-03-01 to 2022-02-28

New technologies for energy generation, storage and delivery, which are started to be developed in Europe during the last decade, require also the considerable effort in the investigation of new materials for energy systems able to store considerable amount of energy in a small volume for a long period of time avoiding its unexpectable losses. This becomes more important when one speaks about energy polygeneration approach, where separate materials for storage and delivery of the electric and thermal energies have to be integrated in one system, and for targeted delivery of bioenergy for bio-inspired synthetic technology platforms (biofactories). There is also a major problem of storage over times between hours and months with the possibility to release or additionally uptake entrapped energy on demand. Corresponding materials have to provide high safety, control, be cheap and reusable. Despite several successful examples of commercialisation of the energy storage materials, in particular for storage of electric energy, the continues research work exists both inside EU as well as in USA and Japan in order to improve energy storage, to miniaturise the materials achieving high energy and controlled release and uptake capacities, to eliminate wasting energy and, finally, to make new materials flexible in terms of delivery of different amounts and types of energies and use of complex energy storage systems.

ENERCAPSULE project contributes to the development of a novel generation of energy storage materials by applying nanoencapsulation approach to the energy-enriched materials for control over the energy uptake and release on demand, to decrease the size of the energy storage unit to nanometre range. In order to demonstrate high versatility and applicability of the proposed scientific goals, two target groups of energy storage materials are chosen, in each of them the nanoencapsulation will foresee application advances and added scientific value from energy-enriched materials in nanoconfined environment and complex storage systems: i) Heat storage materials ii) Materials for delivery of bioenergy (ATP and polyphosphoric acids).
The project consists of four Work packages involving (i) dispersion of the targeted energy materials; (ii) encapsulation into the capsules with controlled energy and materials' delivery properties across the shell, (iii) characterisation of nanoencapsulated energy materials and (iv) application potential of developed multistorage energy systems. Main project achievements are:
1. The successful dispersion and encapsulation of the energy materials have been achieved for both thermal and bioenergy storage. The best method for dispersion nanosized chemical heat capacitors is the application of high intensity ultrasound.
2. Energy capsules showed much higher stability during energy uptake/release cycles (>1000 times) comparing to the bulk materials (up to 5 cycles) without protective capsule shell. Controlled release of the energy has been provided by multifunctionality (barrier, thermal conductivity, sensitivity to the environmental changes) of the shells of nanocapsules. Capsules with reduced graphene oxide-carbon nanotube shell and shell made from SiO2 Pickering emulsion demonstrated high efficiency of encapsulation of phase change materials with the encapsulation yield 70-90% depending on the encapsulation methodology. Thermal conductivity of carbon or inorganic shells is 2-5 times higher than for polymer shells. Capsules with TiO2 and polymer shell and SiO2 shell have been developed and their thermal energy uptake/release properties demonstrated >1000 cycle stability for heat uptake and release.
3. ATP has been incorporated into mesoporous carbon nanoparticles (200 nm size) with pH controlled release properties. Up-scaling methods for 10kg/h fabrication of ATP loaded nanoparticles have been developed.
4. Nanoassemblies of energy nanocapsules with two crystallohydrates demonstrated synergy effect for heat storage and release at different temperatures in one energy storage system.
We have developed a new and facile technology for the nanodispersion of materials for thermal and bioenergy storage in a kg-scale volume. The permeability of the capsule shell can be controlled by external stimuli from the shell completely non-permeable in solutions (e.g. for water or ion molecules) to the shell permeable to the biomacromolecules.
We also demonstrated the application of mesoporous nanoparticles and halloysite clay nanotubes for encapsulation of energy materials and their targeted delivery.
We found unique phenomenon for controlled thermal and electric conductivity of the reduced graphene oxide/CNT capsule shell depending on the capsule size and shell curvature.
We developed energy nanocapsules with shell made of silica nanoparticles (Pickering emulsions).
We demonstrated high cycling stability of the encapsulated phase change materials during heat uptake and release.

General project results:
- Knowledge about behaviour of energy-enriched materials in encapsulated state.
- Knowledge about energy and material exchange between nanocapsules and environment.
- Technology of dispersion of energy materials and encapsulation into multifunctional nanocapsules.
- Development of encapsulated heat capacitors with wide variation of operating temperatures and high corrosion protection stability.
- Precise delivery of bioenergy in synthetic bioreactors.
- High cycle and storage stability of energy storage and delivery systems.
Heat uptake and release by energy capsule