Aluminum ion batteries: electrolytes and cathodes
Great abundance, trivalent oxidation state, high volumetric energy density and inherent safety make aluminum a desirable source of power. Attempts to use aluminum as an electrochemical energy source have been made since the 1800s. To date no great success has been achieved due to difficulties with finding a suitable electrolyte and cathode material. This dissertation explains some of the author’s efforts to overcome these difficulties.
Chapter two reports the results of an investigation of an aluminum anode cell utilizing an ionic liquid electrolyte. Vanadium pentoxide was selected as the cathode material for this cell. The initial results appeared to show reversible aluminum ion based electrochemistry. Closer investigation showed that side reactions with the stainless steel current collector were responsible for the observed behavior.
Chapter three discusses the physicochemical properties of a concentrated aluminum triflate based electrolyte. The FTIR and NMR spectroscopic data show evidence of complex ion pairing taking place in the electrolyte. The electrochemical measurements show this electrolyte to have good ionic conductivity and a wide electrochemical window.
Chapter four shows the results of using the new electrolyte with a hexacyanoferrate cathode material. The electrochemical response of the system shows some degree of rechargeable behavior. This presents what may be the first evidence of aluminum ion intercalation / de-intercalation into a host material from an organic electrolyte.