Electrodes composed of silicon nanoparticles (SiNP) were prepared by slurry casting and then electrochemically tested in a fluoroethylene carbonate (FEC)-based electrolyte. The capacity retention after cycling was significantly improved compared to electrodes cycled in a traditional ethylene carbonate (EC)-based electrolyte.

Hydrothermally synthesized single-crystalline hematite (α-Fe 2 O 3 ) nanorods were investigated as an anode material for Li-ion batteries. Electrodes prepared with this material exhibited initial reversible capacities of 908 mAh g À1 at 0.2 C rate and 837 mAh g À1 at 0.5 C rate, and these capacities were completely retained after numerous cycles. The α-Fe 2 O 3 nanorods average ∼40 nm in diameter and ∼400 nm in length providing a short path for lithium-ion diffusion and effective accommodation of the strain generated from volume expansion during the lithiation/delithiation process.

Silicon and partially oxidized silicon thin films with nanocolumnar morphology were synthesized by evaporative deposition at a glancing angle, and their performance as lithium-ion battery anodes was evaluated. The incorporated oxygen concentration was controlled by varying the partial pressure of water during the deposition and monitored by quartz crystal microbalance, X-ray photoelectron spectroscopy. In addition to bulk oxygen content, surface oxidation and annealing at low temperature affected the cycling stability and lithium-storage capacity of the films. By simultaneously optimizing all three, films of ~2200 mAh/g capacity were synthesized. Coin cells made with the optimized films were reversibly cycled for ~120 cycles with virtually no capacity fade. After 300 cycles, 80% of the initial reversible capacity was retained.

Sn0.9Cu0.1 nanoparticles were synthesized via a surfactant-assisted wet chemistry method, which were then investigated as an anode material for ambient temperature rechargeable sodium ion batteries. The Sn0.9Cu0.1 nanoparticle-based electrodes exhibited a stable capacity of greater than 420 mA h g(-1) at 0.2 C rate, retaining 97% of their maximum observed capacity after 100 cycles of sodium insertion/deinsertion. Their performance is considerably superior to electrodes made with either Sn nanoparticles or Sn microparticles.

Amorphous GeO2 nanoparticles were prepared via a surfactant-assisted hydrothermal process. The effect of the reaction temperature and the surfactant concentration on the morphology of GeO2 particles were investigated. Particles of less than 300 nm were obtained when using 1,2-diaminopropane surfactant in a synthesis carried out at 180(◦)C. The synthesized germanium oxide nanoparticles were evaluated for their utility as the active anode material in Li-ion batteries. The electrode prepared with this material exhibited a stable capacity ∼600 mAh g(-1) at 0.2 C rate for up to 150 cycles in a conventional electrolyte containing ethylene carbonate (EC). The cyclability of the GeO2 nanoparticle electrode was further improved by using a fluorinated ethylene carbonate (FEC) based electrolyte, which showed capacities greater than 600 mAh g(-1) and retained more than 96% of their capacity after 500 cycles at 0.2 C rate. The effect of different electrolyte systems was studied by using electrochemical impedance spectroscopy and electron microscopy.