Nanowire array compositions in which nanowires containing at least one Group IV metal (e.g., Si or Ge) in a single layer or core-shell nanowire structure, wherein, in particular embodiments, the nanowires have a transition metal core and/or are surrounded by or embedded within a metal oxide or metal oxide-ionic liquid ordered host material. The nanowire compositions are incorporated into the anodes of lithium ion batteries. Methods of preparing the nanowire compositions, particularly by low temperature methods, are also described.