Activation Mechanism Of Ga-based Liquid Alloys On Al Anodes And Its Application Research

Al-air battery is a highly efficient energy storage and conversion device with the advantages of high theoretical energy density,low cost,long endurance,environmental friendliness,and high safety.Several modification strategies of Al anodes have been developed including alloying,melting,processing deformation,and heat treatment.These modification strategies have only partially addressed practical issues of Al anode passivation,low power density and poor discharge performance in neutral electrolytes,which enhanced the discharge performance of Al-air batteries.With the upgrading of energy consumption,there has been a growing demand for wearable,portable,and flexible batteries in recent years.As an indispensable component of flexible Al-air batteries,Al metal anodes have not been exhaustively researched as compared to catalytic cathodes until now.In most cases,commercial Al foils or Al wires with no modification are directly used as flexible metal anodes.However,traditional modification strategies of Al anodes are not suitable to develop flexible foil or wire-shaped Al anode materials,which limits the application of flexible Al-air batteries.To address these challenges,the activation effect of Ga-based liquid alloy on Al anodes is proposed and validated based on the high wettability,fluidity,electrical conductivity and self-healing capability of Ga-based liquid alloys.A series of miniaturized,wearable and high-performance metal-air batteries modified with Ga-based liquid alloy have been developed via a loading and activation process of liquid metal which is suitable for large-scale production.The electrochemical performance and discharge behavior of as-prepared Al-air batteries with Ga-based liquid alloy-modified anodes are studied,and Ga-based liquid alloy activation mechanism in different batteries are explored in this thesis.This work expands the modification strategies of anode materials in metal-air batteries,and provides a design foundation for the development and application of novel high-performance metal-air batteries.The main content of this thesis are as follows:1.Based on the activating effect of Ga-based liquid alloys on aluminum,a segregated phase of Ga-based liquid alloy has been designed and constructed within the Al anodes.Al anode materials with high discharge activity in neutral electrolyte have been successfully developed and applied in Al-air batteries.It has been demonstrated that the content of the liquid segregation phase inside the Al anodes can be controlled by adjusting the amount of Ga and In added to the Al anode,thereby influencing the electrochemical performance of the Al anodes.The optimized Al-Ga-In（-Sn）anode in neutral electrolyte exhibits an open circuit potential of-1.626 V and a peak power density of 77.8 m W cm^-2.By studying the phase composition,microstructure,element distribution,and thermodynamic properties of the Al anode materials,the activation effect of the Ga-based liquid alloy segregation phase on Al anode is successfully revealed,and corresponding activation mechanism of the Ga-based liquid alloy is proposed.The proposed mechanism explains the activation process of Al anodes by Ga-based liquid alloys at the atomic level,that is,Al atoms spontaneously migrate to the Ga-based liquid segregation phase in the ingot under the action of concentration gradient,and the mass transfer of Al atoms in the Ga-based liquid segregation phase is accelerated by Malagoni force,so that the Ga-based liquid segregation phase acts as a rapid diffusion channel for Al atoms to participate in the discharge reaction.This work provides new insights into the preparation of high-performance Al anode materials.2.In light of the activation effects on Al anodes,the inherent fluidity and self-healing abilities of Ga-based liquid alloys,a flexible Al-air battery with activated anodes interface consisting of Ga-In liquid particles（GILPs）has been successfully fabricated via a simple surface spin-coating process on Al foil,which can efficiently power flexible eletronics.Experimental results have validated that GILPs loaded on the surface of the flexible Al anodes can not only function as the active site and rapid diffusion channel of Al atoms which play a similar role to the segregation of Ga-based liquid alloy constructed inside Al anodes,but also diffuse into the Al matrix,thereby expanding the activity range of Al and enhancing the overall performance of the battery.Furthermore,the excellent conductivity and self-healing properties of GILPs reduce the mechanical losses of Al anodes during discharge,improving the energy utilization efficiency of the battery.The flexible Al-air battery loaded with 150μg cm^-2 of GILPs achieves a capacity density of 2345 m Ah g^-1 at the current density of 1 m A cm^-2,which is 1.6 times higher than that of unmodified batteries.As-prepared battery exhibits excellent flexibility and robustness against dynamic deformation,and the battery service life can be extended by increasing the thickness of the aluminum anodes.When the anode thickness is increased from 0.1 mm to 1 mm,corresponding battery life is increased from 6.7 h to 68.5 h.In addition,an efficient stacking of the present battery is demonstrated to improve output power of the battery,achieving a stacking efficiency of higher than 93.5%.This work further enriches the mechanism of Ga-based liquid alloy activating Al anode,and provides new modification strategy of flexible Al-anodes and a new way for the design and development of high-performance flexible Al-air battery.3.The activation effect of Ga-based liquid alloys is extended and applied to the Mg-air batteries,and the universality of the GILPs activation mechanism is explored.By constructing GILPs interface on the surface of Mg foil,a high-performance flexible Mg-air battery with GILPs-activated anodes has been successfully developed.The activation effect of Ga-based liquid alloy is also suitable for the modification of Mg anodes.Similar to in Al anodes,GILPs function as active site for Mg atoms to participate in oxidation reactions.Furthermore,GILP can induce a loose and fractured layer consisting of discharge product on Mg anodes during discharge and avoid deterioration of performance due to accumulation of discharge product,thereby improving the overall performance of the battery.The capacity density of Mg-air battery loaded with 24μg cm^-2 GILPs reaches up to 828.74 m Ah g^-1 at 1 m A cm^-2,which is 3.16 times than that of the unmodified battery.Additionally,this flexible Mg-air battery exhibits excellent intermittent discharge capabilities and resistance to dynamic deformation.Finally,the activation mechanism of Ga-based liquid alloy on Al and Mg anodes is compared,the relationship between Ga-based liquid alloy and modifiable metal anodes is clarified,and the general mechanism of Ga-based liquid alloy activating metal anodes is proposed.This work further enriches the theoretical understanding of anode materials for Ga-based liquid alloy-modified metal-air batteries,and broadens the application of Ga-based liquid alloys in the field of metal-air batteries.4.Drawing on the activating effect of Ga-based liquid alloys and their inherent conductivity,stability,and self-healing capabilities,Ga-based liquid alloy-modified printable Al-air battery with low-cost,environmental friendliness and simple structure has been successfully developed.The battery is fabricated by depositing and freeze-drying oxygen reduction ink and Al ink onto GILM conductive coatings on paper substrates.The GILM coating functions as a conductive current collector and activates the printable Al anode material through the activation mechanism of Ga-based liquid alloy.The open-circuit voltage of the printable Al-air battery modified by GILM can reach above 1 V,and as-prepared battery can stably discharge at current densities of0.5～5 m A cm^-2,corresponding to power densities of 0.4 to 1.75 m W cm^-2.The battery can discharge steadily for about 1.5 h at a current density of 1 m A cm^-2,and the capacity density reaches up to 600 m Ah g^-1.Additionally,the battery can integrate the function of energy storage and sensing,thereby reducing system volume and electrical connection complexity.This enables its successful application in the analysis of ethanol content in liquid sensing fields.This work provides new insights for the personalized and large-scale production of Al-air batteries and the development of novel multifunctional integrated sensing systems.In summary,the Ga-based liquid alloys have been employed to modify the anode materials,and highly active and corrosion-resistant anodes have been successfully developed in this thesis.In addition,the activation mechanism of Ga-based liquid alloy on metal anodes has been proposed and applied in the fields of flexible and printed batteries.Through structural design of the battery,portability and flexibility have been achieved,enabling it to meet the requirements of different application.Moreover,this work contributes to the advancement of anode material activation theory for metal-air batteries,and provides a foundation for the development of innovative high-performance metal-air batteries.