Research to develop alternative electrode materials with high energy densities in Li-ion batteries has been actively pursued to satisfy the power demands for electronic devices and hybrid electric vehicles. This critical review focuses on anode materials composed of Group IV and V elements with their composites including Ag and Mg metals as well as transition metal oxides which have been intensively investigated. This critical review is devoted mainly to their electrochemical performances and reaction mechanisms (313 references).

Li–air(O₂) and Li–S batteries have gained much attention recently and most relevant research has aimed to improve the electrochemical performance of air(O₂) or sulfur cathode materials. However, many technical problems associated with the Li metal anode have yet to be overcome. This review mainly focuses on the electrochemical behaviors and technical issues related to metallic Li anode materials as well as other metallic anode materials such as alkali (Na) and alkaline earth (Mg) metals, including Zn and Al when these metal anodes were employed for various types of secondary batteries.

SiO₂ is one of the most abundant materials on Earth. It is cost-effective and also environmentally benign when used as an energy material. Although SiO₂ was inactive to Li, it was engineered to react directly by a simple process. It exhibited a strong potential as a promising anode for Li-ion batteries.

Commercially available solid SiO is composed of amorphous Si with silicon suboxides of various valence states. Solid SiO is thermodynamically unstable at all temperatures, which would disproportionate to Si and SiO₂. Disproportionation of SiO at several temperatures was characterized with various analytical techniques, such as XRD, XPS, NMR and HRTEM methods, and it was found that the sample heat treated at 1000 °C contained well-developed Si nanocrystals uniformly dispersed within an amorphous SiO_x matrix. Using this sample, a nano-Si/SiO_x /graphite composite was obtained by a straightforward high-energy mechanical milling technique. The nano-Si/SiO_x /graphite composite was tested as an anode material for Li secondary batteries, and showed better electrochemical behaviors than those of pure SiO.