A liquid gallium electrode confined in a porous carbon matrix was prepared by vaporization and pyrolysis of Ga͑III͒-phthalocyanine chloride on a nanosized Ga 2 O 3 powder surface, which was followed by carbothermal reduction of Ga 2 O 3 by a carbon matrix. When the electrode was charge/discharge cycled, the liquid Ga component was restored to its original liquid state at the final stage of delithiation, such that any electrode failure modes, for instance, crack formation and electric disconnection that are caused by severe volume change associated with multistage, solid-state Li x Ga ͑0 Ͻ x Յ 2͒ phase transitions, are self-healed by cohesion between liquid Ga droplets.

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Lithium ion batteries (LIBs) have been emerging as a major power source for portable electronic devices and hybrid electric vehicles (HEV) with their superior performance to other competitors. The performance aspects of energy density and rate capability of LIBs should, however, be further improved for their new applications. Towards this end, many Li‐alloy materials, metal oxides, and phosphides have been tested, some of which have, however, been discarded because of poor activity at ambient temperature. Here, it is shown that the InCu binary intermetallic compound (Cu7In3), which shows no activity at room temperature as a result of activation energy required for InCu bond cleavage, can be made active by discharge–charge cycling at elevated temperatures. Upon lithiation at elevated temperatures (55–120 °C), the Cu7In3 phase is converted into nanograins of metallic Cu and a lithiated In phase (Li13In3). The underlying activation mechanism is the formation of new In‐rich phase (CuIn). The de‐lithiation temperature turns out to be the most important variable that controlling the nature of the In‐rich compounds.

Upon lithiation, the active (Ga) and inactive component (Cu) in a binary intermetallic CuGa 2 electrode are converted to nanograins (<50 nm) of Li x Ga and metallic Cu, respectively. It was found that the Cu nanograins are not idling as an inactive ingredient but have a strong influence on the thermodynamic and kinetic properties of Li x Ga phases through a partial bonding to Ga atoms of Li x Ga (CufGa-Li). The Li x Ga phase diagram is altered by the presence of Cu nanograins, eloquently demonstrating that the surface energy becomes more important than internal energy in controlling thermodynamics of nanosized materials. The lithiation rate is slower than that for pure Ga electrode because of activation energy needed for bond cleavage of the partial bonding. The delithiation rate capability is, however, exceptionally good; the capacity at 26 C amounts to 91% of that at 0.13 C, which is indebted to a weakening in the Ga-Li bond by the CufGa partial bonding.