【作者】 曾晓旭；

【导师】 曹楚南； 王建明；

【作者基本信息】 浙江大学 ， 物理化学， 2010， 硕士

【摘要】 铝是一种性能优良的电化学能源体系的阳极材料。它电化学当量高,电极电位负,对环境友好,价格低廉,具有广阔的发展前景。在强碱性溶液中,铝具有良好的阳极溶解性能（放电性能）,但其自腐蚀严重,释放出大量氢气,严重降低了铝阳极的库仑效率和材料利用率,并引发了安全问题。因此,如何在保持碱性铝阳极电化学活性的同时,有效地抑制其自腐蚀,已成为碱性铝电池进一步发展的关键。本文主要研究了表面处理和添加剂对铝在KOH甲醇-水溶液中腐蚀和电化学行为的影响。第一章中,主要概述了铝作为阳极材料的历史发展及各种铝电池,简要阐述了铝在碱性溶液中的电化学行为机理以及合金元素和缓蚀剂对铝阳极行为的影响。第二章中,简单介绍了整个工作的总体思路和研究方案。第三章中,首先研究了表面处理对铝在KOH甲醇-水溶液中的腐蚀和电化学行为的影响。实验表明:在含0.1 mol·L^-1 NaOH,0.02 mol·L^-1 Na₂SnO₃·4H₂O,0.015mol·L^-1 CH₃COONa和0.02 mol·L^-1 Na₄P₂O₇·10H₂O的混合溶液浸泡30 min后,铝电极的电化学性能有了很大改进。在含水量30%的4 mol·L^-1 KOH甲醇-水溶液中,表面处理过的铝电极的析氢腐蚀电流密度为1.12 mA·cm^-2,远小于纯铝电极5.01 mA·cm^-2的腐蚀电流密度。在20 mA·cm^-2电流密度下,表面处理后的铝电极放电时间长达70 min,而纯铝电极却只有15 s。在前述研究的基础上,进一步研究了锡酸钠作为电解液添加剂对表面处理铝电极性能的影响。具有高析氢过电位的金属锡,通过在铝电极表面的沉积,可以减缓铝阳极在电解液中的腐蚀,同时能够有效地抑制铝阳极表面形成致密的钝化膜,从而提高其阳极活性。在电解液中加入0.0015 mol·L^-1 Na₂SnO₃·4H₂O后,在50 mA·cm^-2电流密度下,表面处理电极的放电时间可达25 h,放电电压保持在.1400 mV左右,腐蚀电流密度为0.823mA·cm^-2。第四章中,主要研究了在不同温度下热处理对表面处理过的铝电极在碱性溶液中的电化学行为的影响。研究发现,经300℃热处理的铝电极显示了明显改进的放电性能。在含0.005 mol·L^-1 Na₂SnO₃·4H₂O的含水量30%的4.0 mol·L^-1KOH甲醇-水溶液中,300℃热处理后的铝电极的腐蚀电流密度为1.20 mA·cm^-2,尽管比未热处理前(1.02 mA·cm^-2)稍微有所增大,但是在50 mA·cm^-2电流密度下,它的放电时间长达50 h,是未热处理前（25 h）的2倍。在热处理过程中,表面锡处理的铝电极的表面结构的改变可能是其显示良好恒流放电性能的原因。更多还原

【Abstract】 Aluminum is a very attractive anode material for energy storage and conversion. Aluminum has promising development prospects because of its high electrochemical equivalent,negative electrode potential,environmentally friendly and low price. However,in air or aqueous solution aluminum is prone to passivation,and in strongly alkaline solution it corrodes severely with the production of large amount of hydrogen gases.This wasteful self-corrosion results in unacceptably high-energy loss during standby and the safe problem for the use of batteries.A successful electrode system should keep aluminum electrochemically active whilst reducing its corrosion rate to a low level.This paper mainly investigates the effects of surface treatment and stannate as an electrolyte additive on the corrosion and electrochemical performances of pure aluminum in alkaline methanol-water solutions.The first chapter reviewed the history of the usage of aluminum in electrochemical batteries as well as the development situation of various kinds of aluminum batteries.Then,the author briefly introduced the research development on the corrosion electrochemistry of pure aluminum and aluminum alloy,including corrosion methanism and inhitors,etc.In the second chapter,the general research ideas and experimental details of this dissertation were described.In the third chapter,the effects of surface treatment with stannate on the corrosion and electrochemical behaviors of pure aluminum in alkaline methanol-water solutions have been investigated.In our experimental range the aluminum electrode treated in the solution with 0.1 mol·L^-1 NaOH,0.02 mol·L^-1 Na₂SnO₃·4H₂O,0.015 mol·L^-1 CH₃COONa and 0.02 mol·L^-1 Na₄P₂O₇·10H₂O for 30 min showed relatively low corrosion rate and better discharge performance.In the 4.0 mol·L^-1 KOH methanol-water mixed solutions with 30%water,the treated aluminum electrode presented much low corrosion rate(1.12 mA·cm^-2),compared with the untreated aluminum electrode(5.01 mA·cm^-2);the discharge time of the treated aluminum electrode at the current density of 20 mA·cm^-2 reached 70 min,while the discharge duration of the untreated aluminum electrode was only 15 s.Based on these,the electrochemical performances of the surface-modified aluminum anode in the stannate-containing 4.0 mol·L^-1 KOH solutions with 30%water were further explored. The addition of Na₂SnO₃ in the electrolytes slightly inhibited the corrosion of the modified aluminum electrodes,resulting from the further deposition of metallic tin in the aluminum surfaces.The existence of elemental tin might facilitate the formation of the porous discharge product film on the discharged aluminum surface,notably enhancing the discharge performance of the modified aluminum anode in the stannate-containing electrolyte.In the 4.0 mol·L^-1 KOH methanol-water solution containing 30%water and 0.0015 mol·L^-1 Na₂SnO₃,the discharge time of the treated aluminum electrode at the current density of 50 mA·cm^-2 reached 25 h,maintaining the discharge voltage below -1400 mV.In the fourth chapter,the effects of the heat treatment at various temperatures on the electrochemical behaviors of the surface-modified aluminum electrode in the alkaline solutions were investigated.In the 4.0 mol·L^-1 KOH methanol-water solution containing 30%water and 0.005 mol·L^-1 Na₂SnO₃,the surface-modified aluminum electrode heat-treated at 300℃presented much longer discharge time（50 h） than the corresponding electrode without heat treatment at the current density of 50 mA·cm^-2, although its corrosion current density(1.20 mA·cm^-2) was slightly larger than that of the corresponding electrode without heat treatment.The obviously enhanced discharge performance of the surface-modified aluminum electrode heat-treated at 300℃might result from the change of its surface structure due to the heat treatment.更多还原