文摘
Nanoworm-like Li2FeSiO4鈥揅 composites are synthesized using triblock copolymer Pluronic P123 (poly(ethylene oxide)-b-poly(propylene oxide)-b-poly(ethylene oxide), EO20PO70EO20) as the structure directing agent (SDA) and under the effects of ethanol. As a polar nonaqueous cosolvent, ethanol has effects on the self-organization behavior of Pluronic P123 in water, which determines the final morphologies of the Li2FeSiO4鈥揅 composites synthesized. Li2FeSiO4鈥揅 composite nanoparticles are obtained if no ethanol is added into the system during the synthesis process. When tested as lithium-ion battery cathodes, the Li2FeSiO4鈥揅 nanoworms show superior electrochemical performances. At the rate of 1 C (1 C = 166 mA g鈥?) the discharge capacity of the Li2FeSiO4鈥揅 nanoworms can reach 166 mAh g鈥? in the voltage window of 1.5鈥?.8 V at room temperature. At the rates of 5, 10, and 20 C, the discharge capacities of the Li2FeSiO4鈥揅 nanoworms can stabilize at 120, 110, and 90 mAh g鈥?, respectively, and do not show obvious declines after hundreds of cycles. This performance of the Li2FeSiO4鈥揅 nanoworms at high rates is better than that of the Li2FeSiO4鈥揅 nanoparticles synthesized and many other Li2FeSiO4/C composites reported in the literature. The excellent electrochemical performances of the Li2FeSiO4鈥揅 nanoworms are believed to be related to the small sizes of the Li2FeSiO4 nanocrystals inside the nanoworms and the carbon that coats and embeds the nanocrystals.
Keywords:
Li2FeSiO4鈭扖; nanoworms; cathode materials; lithium ion batteries