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X-ray absorption near-edge spectroscopy (XANES) and extended X-ray absorption fine structure (EXAFS) spectroscopy have been used to investigate the electrochemical reactions of NiCo 2 O 4 in lithium and sodium test cells. Nanosized particles of NiCo 2 O 4 were prepared by the thermal decomposition of a mixed oxalate precursor and used as active electrode material. Ni K and Co K XANES results give evidence of the successive steps in the reduction mechanism of the oxide during the first cell discharge. In a first step NiCo 2 O 4 reacts with lithium and sodium and the reduction of both Ni 3+ and Co 3+ to the 2+ oxidation state is shown by a peak shift to lower energy values. As a result, sodium oxide or lithium oxide and the transition metal monoxides are formed. Second, metallic products are formed, in which the average coordination numbers of the nearest neighbors for Ni and Co derived from the EXAFS data are 4 and 5, respectively, associated with ca. 1 nm particle size. These novel ultrafine particles are stabilized in the Li 2 O matrix of the discharged electrodes. Reoxidation of the metallic products up to a divalent state of Ni and Co in the form of monoxides is achieved during the charge process of the electrochemical cells.

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The cotreatment of spent pot-lining (SPL), a high fluoride (20 wt %), and cyanide (up to 1 wt %) waste generated in aluminum smelting, and Al 3+ wastewaters generated by the aluminum anodizing industry was identified in this work as a treatment alternative that holds the potential to virtually remove the need for purchasing chemical reagents while keeping carbon dioxide emissions to a minimum. The process proposed involves fluoride leaching with anodizing wastewaters and precipitation of AlF 2 OH by treatment with caustic waste from the aluminum anodizing industry. AlF 2 OH can be directly injected into fluidized beds that are used to convert Al(OH) 3 to AlF 3 . Since AlF 3 is used in primary aluminum smelting, aluminum and fluoride from aluminum industry wastes such as SPL and anodizing wastewaters are recovered in a form that can be readily used as a feedstock in the aluminum industry. In this paper, the results of SPL leaching studies using aluminum anodizing waste are presented together with a model of the solution equilibria, which has been used to interpret experimental observations. Mild leaching temperatures were used and no chemical reagents other than anodizing waste were necessary to extract the soluble fluoride.

Lithium cobalt oxide (LiCoO(2)) particles are modified using rotor blade grinding and re-annealing and used as the active electrode material versus lithium in the 3-0 V potential interval, in which a maximum capacity of 903 mA h g(-1) is achieved. X-ray absorption near edge structure spectra reveal the complete reduction of Co(3+) to Co metal at 0 V. Cell recharge leads to an incomplete reoxidation of cobalt. A maximum reversible capacity of 812 mA h g(-1) is obtained, although a poor capacity retention upon prolonged cycling may limit its application.