Periodic Reporting for period 1 - FlexBatteries (Flexible Li ion Batteries via Nanocrystal-Nanocarbon Scaffolded Structures)
Période du rapport: 2016-08-01 au 2018-07-31
Li ion batteries have fuelled a revolution in the development of electronic gadgets such as smart phones, laptops and miscellaneous devices which in turn have transformed human perception of the world in unprecedented ways. These electronic devices are mostly powered by Li ion batteries, and as these technologies evolve further, Li ion batteries also need to evolve to meet increasingly stringent standards and conditions for their sustained applications. Recently, one particular trend is the emergence of flexible electronics ranging from wearables and smart cards to body-worn health monitors and humanoids. To support the development of these further, Li ion batteries need to be physically flexible and highly performing and capable of delivering simultaneously the functionality, compatibility, reliability and longevity. This project has been focused on the development and characterisation of novel material platform (namely nanocarbon and nanocrystal) by demonstrating their use in the next-generation batteries and by enabling a new understanding of the complex battery electrochemistry to guide the design of energy materials and fabrication of battery electrodes. To this end, this project has provided timely opportunities to contribute to research programs that have achieved new design and fabrication method for flexible batteries with ultra-thick electrodes offering battery performance beyond the state-of-the-art. Further, applying rigorous methodologies for battery characterisation via the use of battery advanced diagnostics tools (e.g. operando neutron depth profile and operando x-ray) has shed new light on battery electrochemistry (including post Li ion chemistries such as lithium-oxygen and lithium-sulphur), thus developing new design principles for next-generation batteries with improved energy density, mechanical pliability, cost-efficiency, battery safety and longevity. These can also be extended to design electrode materials and batteries for electric vehicles and grid-scale storage, thus aiding adaptation of renewable energy.
1. Using iron oxide nanoparticles and carbon nanotubes, a new type of oxygen cathode for lithium-oxygen (Li-O2) batteries has been proposed. Besides this, iron oxide seeds on carbon nanotubes improve the crystallinity of lithium peroxide and its reversible formation and decomposition on charge-discharge cycles, leading to high columbic efficiency and high capacities. (Adv.Energy.Mat 2018).
2. We demonstrated that the current industrial methods for producing Li ion electrodes can be minimally altered to produce thick (more than 100 micron) and freestanding electrodes without compromising both the energy or power density. This is achieved by a technique called immersion precipitation, through which the electrodes after slurry coating are immersed in water to solidify the coating and the electrode layer delaminates spontaneously, instead of drying on the current collectors. The full battery can operate while fully bent (180) to full crease (Accepted in Journal of Power Sources 2019).
3. Perylene diimide dye polymer dyes via a polymer grafting method was shown to yield several grams in a scalable way which has remained as a challenge with regard to its scalability. When adopted as binder for lithium iron phosphate nanoparticle based electrodes, Perylene based electrodes offered high capacities as well as columbic efficiencies at very low carbon amount (2%). This work achieves a milestone in the development of binder for Li ion technology because it not only would enable design of advanced flexible Li ion batteries but the development of batteries with photo rechargeability since Perylene is a dye and has a light absorption in the visible spectral range of 500-600 nm (This work is under revision ACS Appl. Energy Mater.2019).
4. Detection of Li ions in battery electrode environment is extremely difficult owing to its small size and high reactivity. To enable selective detection and quantification of Li across battery electrodes, in this research line, neutron depth profiling has been used. Li (naturally occurring 6Li) absorb neutrons and decay into tritium and helium particles. By measuring the concentration of tritium particles and their energy loss as they travel through electrodes, the depth at which isotope originated can be determined, which in turn indicate the position and distribution of Li ions across battery electrodes with atomic precision. Using this, Li-S batteries were investigated and new insights into Li-S battery chemistry in terms of polysulphide dissolution, migration and their re-utilisation with regard to battery capacity and longevity have been developed. This study can guide the design of new battery materials and battery architectures for high energy dense and low-cost batteries. This work has been published in J. Am. Chem. Soc.(2019), 141, 3614280-14287.
2. We demonstrated that the current industrial methods for producing Li ion electrodes can be minimally altered to produce thick (more than 100 micron) and freestanding electrodes without compromising both the energy or power density. This is achieved by a technique called immersion precipitation, through which the electrodes after slurry coating are immersed in water to solidify the coating and the electrode layer delaminates spontaneously, instead of drying on the current collectors. The full battery can operate while fully bent (180) to full crease (Accepted in Journal of Power Sources 2019).
3. Perylene diimide dye polymer dyes via a polymer grafting method was shown to yield several grams in a scalable way which has remained as a challenge with regard to its scalability. When adopted as binder for lithium iron phosphate nanoparticle based electrodes, Perylene based electrodes offered high capacities as well as columbic efficiencies at very low carbon amount (2%). This work achieves a milestone in the development of binder for Li ion technology because it not only would enable design of advanced flexible Li ion batteries but the development of batteries with photo rechargeability since Perylene is a dye and has a light absorption in the visible spectral range of 500-600 nm (This work is under revision ACS Appl. Energy Mater.2019).
4. Detection of Li ions in battery electrode environment is extremely difficult owing to its small size and high reactivity. To enable selective detection and quantification of Li across battery electrodes, in this research line, neutron depth profiling has been used. Li (naturally occurring 6Li) absorb neutrons and decay into tritium and helium particles. By measuring the concentration of tritium particles and their energy loss as they travel through electrodes, the depth at which isotope originated can be determined, which in turn indicate the position and distribution of Li ions across battery electrodes with atomic precision. Using this, Li-S batteries were investigated and new insights into Li-S battery chemistry in terms of polysulphide dissolution, migration and their re-utilisation with regard to battery capacity and longevity have been developed. This study can guide the design of new battery materials and battery architectures for high energy dense and low-cost batteries. This work has been published in J. Am. Chem. Soc.(2019), 141, 3614280-14287.
1. One of the main contributions to the development of next-generation Li ion battery electrodes is the demonstration of a recipe that practically achieves thick electrodes (doubling the current thickness) and this amounts to circa 20% improvement in energy density of Li ion battery technology. This contribution represents a step change in flexible Li ion battery electrode design. If optimized, this would massively benefit the electrification of vehicles, where batteries need to deliver long-drive range.
2. Neutron depth profiling was successfully used to provide conclusive views on Li-S batteries that are currently bottlenecked by a number of technical problems such as the dissolution of battery active components in electrolytes and their shuttling between electrodes degrading battery round strip efficiency. Results obtained show that how such deleterious processes can be mitigated and provide new design principle for the development of high energy density and cost-effective Li-S batteries.
3. As opposed to the current battery binders (PVDF, fluorine containing), it is proposed that light active and electroactive binders (Perylene dye polymers-fluorine free) can be used to fabricate Li ion battery electrodes, which may also open up new possibilities to realise light rechargeable batteries, which are still in their infancy, but the preliminary results obtained show that Perylene dye polymers can be integrated into the state-of-the-art li ion battery electrodes to improve energy density.
4. Bifunctional nanocarbon and nanocrystal (iron oxide seeds on carbon nanotubes) has been demonstrated to significantly improve the crystallinity and morphology of charge-discharge products (lithium peroxide and its reversible formation and decomposition) on lithium-oxygen battery cycling, leading to high round-trip efficiency and high capacities, which circumvents a major limitation in lithium-oxygen batteries, thus enabling progress beyond the current Li ion batteries.
2. Neutron depth profiling was successfully used to provide conclusive views on Li-S batteries that are currently bottlenecked by a number of technical problems such as the dissolution of battery active components in electrolytes and their shuttling between electrodes degrading battery round strip efficiency. Results obtained show that how such deleterious processes can be mitigated and provide new design principle for the development of high energy density and cost-effective Li-S batteries.
3. As opposed to the current battery binders (PVDF, fluorine containing), it is proposed that light active and electroactive binders (Perylene dye polymers-fluorine free) can be used to fabricate Li ion battery electrodes, which may also open up new possibilities to realise light rechargeable batteries, which are still in their infancy, but the preliminary results obtained show that Perylene dye polymers can be integrated into the state-of-the-art li ion battery electrodes to improve energy density.
4. Bifunctional nanocarbon and nanocrystal (iron oxide seeds on carbon nanotubes) has been demonstrated to significantly improve the crystallinity and morphology of charge-discharge products (lithium peroxide and its reversible formation and decomposition) on lithium-oxygen battery cycling, leading to high round-trip efficiency and high capacities, which circumvents a major limitation in lithium-oxygen batteries, thus enabling progress beyond the current Li ion batteries.