Germanium-tin (Ge(1-x)Sn(x)) alloy nanocrystals were synthesized using a gas-phase laser photolysis reaction of tetramethyl germanium and tetramethyl tin. A composition tuning was achieved using the partial pressure of precursors in a closed reactor. For x < 0.1, cubic phase alloy nanocrystals were exclusively produced without separation of the tetragonal phase Sn metal. In the range of x = 0.1-0.4, unique Ge(1-x)Sn(x)-Sn alloy-metal hetero-junction nanocrystals were synthesized, where the Sn metal domain becomes dominant with x. Thin graphitic carbon layers usually sheathed the nanocrystals. We investigated the composition-dependent electrochemical properties of these nanocrystals as anode materials of lithium ion batteries. Incorporation of Sn (x = 0.05) significantly increased the capacities (1010 mA h g(-1) after 50 cycles) and rate capabilities, which promises excellent electrode materials for the development of high-performance lithium batteries.

Lithium-metal anode has fundamental problems concerning formation and growth of lithium dendrites, which prevents practical applications of next generation of high-capacity lithium-metal batteries. The synergistic combination of solid polymer electrolyte (SPE) crosslinked with naturally occurring terpenes and lithium-powder anode is promising solution to resolve the dendrite issues by substituting conventional liquid electrolyte/separator and lithium-foil anode system. A series of SPEs based on polysiloxane crosslinked with natural terpenes are prepared by facile thiol-ene click reaction under mild condition and the structural effect of terpene crosslinkers on electrochemical properties is studied. Lithium powder with large surface area is prepared by droplet emulsion technique (DET) and used as anode material. The effect of the physical state of electrolyte (solid/liquid) and morphology of lithium-metal anode (powder/foil) on dendrite growth behavior is systematically studied. The synergistic combination of SPE and lithium-powder anode suggests an effective solution to suppress the dendrite growth owing to the formation of a stable solid-electrolyte interface (SEI) layer and delocalized current density.

Solid polymer electrolytes (SPEs) for all-solid-state lithium-ion batteries are prepared by simple one-pot polymerization induced by ultraviolet (UV) light using poly(ethylene glycol) methyl ether methacrylate (PEGMA) as an ion-conducting monomeric unit and tannic acid (TA)-based crosslinking agent and plasticizer. The crosslinking agent and plasticizer based on natural resources are obtained from the reaction of TA with glycidyl methacrylate and glycidyl poly(ethylene glycol), respectively. Dimensionally stable free-standing SPE having a large ionic conductivity of 5.6×10(-4)  Scm(-1) at room temperature can be obtained by the polymerization of PEGMA into P(PEGMA) with a very small amount (0.1 wt %) of the crosslinking agent and 2.0 wt % of the plasticizer. The ionic conductivity value of SPE with a crosslinked structure is one order of magnitude larger than that of linear P(PEGMA) in the waxy state.

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