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.

Lithium-ion rechargeable batteries are used as portable power sources for a wide variety of electronic devices, such as cellular phones, notebook computers, and camcorders. Intensive research efforts have been made over the past decade to increase the gravimetric and volumetric energy density of lithium ion batteries. At present, graphite (372 mA h g -1 ) is used as an anode material for lithium ion batteries, but higher capacity alternatives are being actively pursued. Among the many possible alternatives, a lot of work has been devoted to Sn-based oxide, [1][2][3] Si-based composite, [4,5] transition metal oxide, [6,7] metal nitride [8,9] and metal phosphide [10][11][12][13][14] systems, due to their ability to react reversibly with large amounts of Li per formula unit. Although alloy-based systems have a higher energy density, they suffer from poor capacity retention, since a large volume change occurs during charge/discharge. Among these alternatives, a concept based on the quasi-topotactic intercalation mechanism was proposed, in which lithium is inserted into monoclinic binary MnP 4 to form the cubic ternary Li 7 MnP 4 phase.[10] Since then, Li insertion/extraction in transition metal phosphides has been investigated as a possible candidate for the anode material in lithium ion batteries. [10][11][12][13][14] In these systems, commercial red P and transition metals were used to synthesize metal phosphides, but the energy density is reduced due to the heavy transition metals employed. If phosphorus were used for electrode materials, it would have a good energy density, but little is known about its electrochemical behavior, since commercial red P has an amorphous structure with a poor bulk conductivity and poor cyclability. Phosphorus, an element of the fifth group in the periodic table, has three main allotropes: white, red, and black. [15] Among these modifications of allotropes, [16][17][18][19] black phosphorus is thermodynamically the most stable, insoluble in most solvents, practically non-flammable, and chemically the least reactive form, and exists in three known crystalline modifications (orthorhombic, rhombohedral, and simple cubic), as well as in an amorphous form. [20][21][22][23] Since orthorhombic black phosphorus was obtained from white phosphorus at 200°C and 1.2 GPa, [24] many studies designed to synthesize black phosphorus have been reported. [25][26][27] However, the basic concept of a high temperature and high pressure being required has not been changed, and black phosphorus still remains difficult to synthesize, and has the lowest commercial value of the three forms. Considering that orthorhombic black phosphorus exhibits a layer structure [20,21] similar to that of graphite, which is currently used as an anode material for Li ion batteries, we developed a simple method of transforming commercially available amorphous red phosphorus into orthorhombic black phosphorus using a high energy mechanical milling (HEMM) technique at ambient temperature and pressure. It is known that the tempera...

No abstract

SiO 2 is one of the most abundant materials on Earth. It is costeffective and also environmentally benign when used as an energy material. Although SiO 2 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.