New breakthrough in battery charging technology
    Scientist invents way to trigger artificial photosynthesis to clean air

    This is one of those stories that may not be market ready yet but opens many doors for other applications and development 

    (a) Schematic representation of the FTO/LFP NPs/DYE electrode; (b) open circuit voltage (OCV) under Neon light exposure (red line): the voltage after a plateau at 3.40 V increased to 3.75 V and in the dark using a black box (blue line), the voltage, as expected, slightly decreases from 3.44 to 3.41 V in 500 h. The inset shows the change in OCV upon illumination with a solar simulator (green line).

    This is how the press release read.

    Who hasn’t lived through the frustrating experience of being without a phone after forgetting to recharge it? This could one day be a thing of the past thanks to technology being developed by Hydro-Québec and McGill University.

    Lithium-ion batteries have allowed the rapid proliferation of all kinds of mobile devices such as phones, tablets and computers. These tools however require frequent re-charging because of the limited energy density of their batteries.

    “With smart phones now, you can basically carry your whole office in that device, they are loaded with all sorts of applications so you need a lot of power to use it everyday and sometimes, you don’t have access to a plug to recharge,” explains Professor George P. Demopoulos, chair of Mining and Materials Engineering at McGill University.

    This has led to the development of portable solar chargers but these hybrid devices are difficult to miniaturize due to their complex circuitry and packaging issues.

    To solve this problem, scientists at McGill University and the Hydro-Québec’s research institute are working on a single device capable of harvesting and storing energy using light. In other words, a self-charging battery.

    A first milestone

    A novel concept presented in a Nature Communications paper by Professor Demopoulos and researchers at Hydro-Québec paves the way to these so-called light-charged batteries.

    The study shows that a standard cathode from a lithium-ion battery can be “sensitized” to light by incorporating photo-harvesting dye molecules. “In other words,” says Dr. Andrea Paolella, the study’s lead author and researcher at Hydro-Québec, “our research team was able to simulate a charging process using light as a source of energy.”

    Scientists will now have to build an anode, the storage component, which will close the device’s circuit, allowing energy produced by the cathode described in Nature Communications to be transferred and stored. If they succeed, they will have built the world’s first 100% self-charging lithium-ion battery.

    Potential for mobile devices

    The research team is already working on phase two of this project, thanks to a $564,000 grant from the Natural Sciences and Engineering Research Council of Canada.

    “We have done half of the job,” says Professor Demopoulos, co-senior author of the paper with Hydro-Québec’s Dr. Karim Zaghib, a world leading expert on batteries. “We know that we can design the electrode that absorbs light. “This grant will give us the opportunity to bridge the gap and demonstrate that this new concept of a light-chargeable battery is possible.”

    “I’m an optimist and I think we can get a fully working device,” says Paolella, who is also a former post-doctoral student from McGill. “Theoretically speaking, our goal is to develop a new hybrid solar-battery system, but depending on the power it can generate when we miniaturize it, we can imagine applications for portable devices such as phones”.

    “Hydro-Québec has a strong global position with regard to the development of innovative, high-performance and safe battery materials,” says Karim Zaghib Director – Energy Storage and Conservation at IREQ, Hydro-Québec’s research institute.

    While it may take a few years to complete the second phase of the project, Professor Demopoulos believes this “passive form of charging” could play an important role in portable devices of the future…

    This is how the Published Paper Reads


    Recently, intensive efforts are dedicated to convert and store the solar energy in a single device. Herein, dye-synthesized solar cell technology is combined with lithium-ion materials to investigate light-assisted battery charging. In particular we report the direct photo-oxidation of lithium iron phosphate nanocrystals in the presence of a dye as a hybrid photo-cathode in a two-electrode system, with lithium metal as anode and lithium hexafluorophosphate in carbonate-based electrolyte; a configuration corresponding to lithium ion battery charging. Dye-sensitization generates electron–hole pairs with the holes aiding the delithiation of lithium iron phosphate at the cathode and electrons utilized in the formation of a solid electrolyte interface at the anode via oxygen reduction. Lithium iron phosphate acts effectively as a reversible redox agent for the regeneration of the dye. Our findings provide possibilities in advancing the design principles for photo-rechargeable lithium ion batteries.


    The design of a device that is simultaneously a solar energy convertor and a battery represents a paradigm-shifting energy storage concept that allows to charge a battery without any external power supply1,2. The first photo-rechargeable battery was proposed in 1976 by Hodes et al.3 using a three-electrode system composed of cadmium selenide/sulfur/silver sulfide (CdSe/S/Ag2S), followed in 1977 (ref. 4) by the ternary system n-cadmium selenide telluride/caesium sulfide/tin sulfide (CdSe0.65Te0.35/Cs2Sx/SnS). In 1990, Kanbara et al.5 investigated a photo-reaction on a semiconductor silicon/silicon oxide (P-I aSi/SiOx) electrode using silver iodide tungstanate (Ag6I4WO4) and observed a photo-sensitizing effect on the surface of SiOx. More recently, a solar rechargeable battery consisting of a hybrid titania (TiO2)/poly(3,4-ethylenedioxythiophene, PEDOT) photo-anode and a perchlorate (ClO4)-doped polypyrrole counter electrode was proposed by Liu et al. in 2012 (ref. 6). In 2014, Yu et al.7 reported charging of a lithium–oxygen (Li–O2) battery with the assistance of a redox-coupled dye photo-electrode. In the meantime, in 2015 Li et al.8 integrated a TiO2-based electrode in a three-electrode system comprising a lithium iron phosphate (LiFePO4; LFP)/lithium metal cell using triodide/iodide (I3/I) as a redox agent in a separate electrolyte compartment. All these devices are basically three-electrode systems that have two linked sections, namely: one dedicated to solar energy conversion and the other dedicated to energy storage as discussed recently by Li et al.9. Along the same lines, Xu et al.10 connected a perovskite methylammonium lead iodide (CH3NH3PbI3)-based solar cell in series with a Li-based cell (LFP cathode and a Li4Ti5O12 anode) and observed good cycling stability. Also in 2015, Thimmappa et al.11 proposed a chemically rechargeable photo-battery device utilizing potassium iron hexacyanoferrate prussian blue analogue (KFe[Fe(CN)6] and titanium nitride (TiN) in which: the photo-electrons generated on the TiN electrode assist in battery discharging while sodium disulphate Na2S2O8participate in charging as is consumed and continuously regenerated. In another development, Li et al.12 proposed a very innovative device, integrating a CdSe@Pt photocatalyst into Li–S batteries via which direct solar energy storage takes place in the form of H2 production. In 2015, Yu et al.13 designed a photo-rechargeable Li-iodide flow battery, using a TiO2-dye photoelectrode via linkage of an I3/I based catholyte for the conversion and storage of solar energy. Compared to the previous concepts, the devices described by Li and Wu are single systems. In Li’s device, the electrons are consumed by the reduction of hydrogen (2H++2e→H2) while in Wu’s device, a constant flow of a reversible I3/I redox agent is required. For the two-electrode system, Liu et al.14suggested in 2015 the use of a graphitic carbon nitride (C3N4) photocatalyst to reduce the charging voltage in a Li–O2 battery.

    In this paper, we report a two-electrode system involving direct photo-oxidation of LFP nanocrystals by light irradiation in the presence of the N719 dye as hybrid photo-cathode, Li metal as anode, and LiPF6 organic carbonate solvent (EC/DEC/VC) as electrolyte that corresponds to Li-ion battery charging. We utilize LFP as the cathode material because of its stability and safety as well as its favourable redox potential. The latter, 3.4 V versus Li+/Li (refs 15, 16), is very close to that of the classic I3/I redox couple (3.1 V versus Li+/Li) used in the dye-sensitized solar cell invented by O’Regan and Grätzel in 1991 (ref. 17). Dye-sensitization generates electron–hole pairs with the holes aiding the chemical conversion of LFP (triphylite) nanoplatelets to FePO4(heterosite) at the cathode and the electrons utilized via oxygen reduction in the formation of solid electrolyte interface (SEI) at the anode made-up of lithium-carbonate-based species. The photo-assisted delithiation of LFP is reversible upon galvanostatic discharge. Our findings open possibilities in designing photo-rechargeable Li-ion batteries based on a two-electrode device configuration.

    Journal Reference

    New breakthrough in battery charging technology
    Scientist invents way to trigger artificial photosynthesis to clean air
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