| Aluminum-air batteries have widely prospects,due to their ultra-high theoretical energy density(8.14 k W·h·kg-1)after the lithium-air batteries.However,the undistributed consumption of anodes and the production of aluminum residues may cause problems of the stability and safety of the batteries.On the other hand,the batch performance of the batteries is poor,which means the batteries only sustain working.Therefore,the industrialization of aluminum-air batteries was severely limited.To settle above problems,optimizing current distribution,designing the filter layer,and the standby protection,were using to improve the anode distributed corrosion,block the aluminum residue,reduce self-corrosion in standby conditions.Consequently,the discharge stability,safety,and the batch performance of the batteries were improved.The research on the current density is mainly achieved through the design and optimization of the position?side,off-set and median?of the lug.Theoretical calculation was performed by COMSOL Multiphysics? software,which exhibited the potential and primary current density distribution of the anode surface.Electrochemical tests also showed that the median lug aluminum alloy anodes have the best electrochemical performance,negative open circuit potential,the lowest corrosion rate(6.27 m A·cm-2),and low corrosion resistance.Compared with the side lug anode,the median lug anode has excellent high-current performance,and discharge potential and power density of the batteries increased about 3.4% in 100 m A·cm-2 current density,while 12.5% in 200 m A·cm-2 current density.A fully covered layer was designed to filter the aluminum slag generated by the uneven corrosion of the anode.The thermal and chemical stability of 5 materials were compared such as nylon,non-woven fabric,cotton cloth,PVC material,and PC material.Nylon has good heat and alkali resistance,small shrinkage?about 0.4%?,low ohmic resistance?0.38??,and minimal influence to the electrochemical performance of the anode.The discharge performance test of the battery shows that the nylon filter layer can be used for a long-term discharge,and has a significant effect on the interception of aluminum residue,which can effectively avoid the safety problems caused by blocking the electrolyte channel and contact short circuit.At the same time,it has the function of intercepting the by-products of the battery dissolved in the electrolyte,reducing the turbidity of the electrolyte and the content of byproducts.Compared with batteries without nylon filter layer,the discharge potential and power density increase nearly 5.6% at a current density of 100 m A·cm-2.The aluminum loss of continuous or batch discharge of aluminum-air battery was studied,which shown that the standby protection was necessity.Four standby protection methods?poor out lye,water washing,soak in water,pickling?were designed and researched on the self-corrosion performance of aluminum alloy.Furthermore,different standby protection media?malic acid,acetic acid,citric acid,sodium bicarbonate?have been compared and studied on standby protection effect,results show that the use of malic acid solution(0.1mol·L-1)has the best standby protection and discharge stability,and the shortest time to recovery?1min?.The malic acid has a larger ionization constant,with 2-COOH bond,which can be ionized out the higher concentration of H+,consume the residual on the electrode surface completely.The corrosion of the anode is weak(2.303×10-3 m A·cm-2)in the malic acid,which is reduced to a certain extent the degree of polarization.And SEM test results also show that malic acid has compatible to the diffusion layer and the catalytic layer. |
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