| This work describes combinatorial investigations of high-capacity thin film negative electrode materials for Li-ion batteries. Amorphous alloy electrode materials are emphasized since they offer much better charge/discharge capacity retention than their crystalline counterparts. Various combinatorial and high-throughput methods, designed to deal with the experimental challenges posed by amorphous materials, are described.; The aim is to understand the electrochemistry of the Si-Al-M (M = transition metal such as Cr, Fe, Mn or Ni) system. Certain compositions of Si-A1-M can be mass produced as amorphous alloys, offer high capacities, and good capacity retention. Separate investigations of the Si-M, Al-M, and Al-Si systems were performed since the literature for each system is either conflicting or non-existent.; The electrochemical performance of Si-M can be explained by assuming the presence of active amorphous Si and inactive nanocrystalline SiM. Diffusion effects lower the observed capacity for compositions above 30 atomic percent M for all tested values of M except Mn.; Mossbauer and XRD measurements suggest that M atoms are not randomly distributed throughout Al-M samples, but instead occur in isolated and clustered sites. A phenomenological model based on the relative amounts of isolated and clustered sites is presented to explain the capacities of Al1 -xMx samples observed at room and elevated temperature. Interactions between Si, Al and Li complicate the electrochemistry of the Si-Al system. Measurements suggest the presence of AlLi, AlLiSi or Al3Li7Si4, Al2Li18Si 6, and Li15Si4 in fully-lithiated films.; Capacities in the Si-Al-M system are dominated by the influence of Al-M and Si-M interactions at high Al and Si contents, respectively. Compositions with less than 80 atomic percent Si and more than 10-20 atomic percent M remained amorphous during Li insertion and removal and could be used as high capacity electrode materials. There is also some evidence all Si-Al-M equilibrium phases are inactive. Possible future research directions based on the insight gained during this research are provided. |
