Constructure And Performance Enhancement Of Miniature Zinc-air Battery

In recent years,microfluidic chips for point-of-care test(POCT)show the advantages of low cost,easy operation,high sensitivity,and high pertinence,which embraces a good development prospect in the field of biomedicine.The necessary of developing the miniature power source that matches its normal operation has become a key issue.At present,the most common miniature power source is lithium-ion battery with a sufficient power support.However,it still possesses disadvantages such as low theoretical energy density,electrolytes environment unfriendly,professional and complicated treatment,and high capital costs.To address above issues,developing of a high energy density,low cost,and environmental friendly miniature power source has become a research hotspot.The work starts with the perspective of constructing a new type of miniature zinc-air battery,and propose several electrode and cell structures to promote the battery performance in the view of optimizing the mass-transport process.Herein,by coupling the reaction principle of the zinc-air battery and concept of microfluidic fuel cell,zinc is used to replace the anode in conventional microfluidic fuel cell,relieving the passivation in the zinc-air battery,hydrogen evolution and limited fuel-transportation problems under high current density,effectively improving the battery output performance.Besides,to increase the compactness of zinc-air batteries as a suitable miniature power source,paper-based zinc-air batteries are further studied to reduce battery processing and manufacturing costs,making battery processing and operation easy to system integration.The hollow channel structure is adopted to improve the wettability of the cathode of the paper-based zinc-air battery,and promote the battery performance.Herein,we propose three types of miniature zinc-air fuel cells,including microfluidic zinc-air fuel cell based on a planar anode,microfluidic zinc-air fuel cell based on a porous zinc anode,paper-based zinc-air battery with hollow channels,and a flexible paper-based battery.The impact of electrolyte concentration,volumetric flow rate,and flow manner on battery performance characteristics is studied.The main research results and conclusions in the study are summarized as following:1.A microfluidic zinc-air fuel cell based on a flat anode was constructed.By replacing the conventional anode with a zinc foil anode,the mass-transportation characteristics at the anode side were improved,and the zinc anode passivation was relieved by controlling the electrolyte flow manners.When the electrolyte concentration was 6 M and volumetric flow rate was 1200μL/min,the peak power density of battery reached 194 m W/cm~2with the discharge life of 4926 seconds at a current density of 100m A/cm~2,and the zinc utilization rate is as high as 90%.2.Using porous zinc foam as the anode,it can increase the electrochemical active area and reduce the mass transfer resistance,finally lowering the ohmic internal resistance of the battery.The microfluidic zinc-air fuel cell based on the porous zinc anode achieved the peak power density of 266 m W/cm~2.The battery showed a discharge life of 5078 seconds at a current density of 100 m A/cm~2.3.A paper-based zinc-air battery with a hollow channel structure was constructed.The hollow channel structure effectively increased the electrochemical active area of the cathode,and boosted the cathode reaction kinetics and battery performance.The peak power density of paper-based zinc-air battery with the hollow channel on the two electrodes reached 102 m W/cm~2,which was 100%higher than that of conventional structure.