正极材料纳米Li2FeSiO4/C的溶胶-凝胶法合成及电化学性能

采用溶胶-凝胶法,以抗坏血酸作为碳源并添加表面活性剂聚乙二醇（PEG）合成纳米复合材料Li2FeSiO4/C。研究了PEG对Li2FeSiO4/C结构及电化学性能的影响。结果表明：添加PEG后合成的纳米Li2FeSiO4/C颗粒细小（约50 nm）,表面均匀包覆一层碳。因此,纳米复合粉体Li2FeSiO4/C在充放电过程中具有更小的扩散阻力和更高的电导率,而均匀的碳层能够减少活性物质与电解液之间副反应的发生。室温下以C/16倍率充放电,首次放电比容量为138.2mA h/g,并且在不同倍率下循环40次后仍保持在130.4 mA h/g。

Synthesis of Nanostructured Li2FeSiO4/C Cathode Material by Sol-Gel Method and its Electrochemical Properties

The nanocomposites of Li2FeSiO4/C were synthesized with polyethylene glycol(PEG) as a surfactant and L-ascorbic acid as a carbon additive by a sol-gel method.The effect of PEG on the structures and electrochemical properties of Li2FeSiO4/C were investigated.The results show that the nanocomposites of Li2FeSiO4/C synthesized with PEG are dispersed spherical particles(about 50 nm),which are embedded into a uniform carbon film.As a result,the nanostructured Li2FeSiO4/C composites exhibited a less ad-ditional barrier and a higher electronic conductivity during the charge/discharge process.The uniform carbon coated on the particles restrained the side reactions occurring at the electrode-electrolyte interface.The nanocomposites of Li2FeSiO4/C delivered a first dis-charge capacity of 138.2 mA?h/g at C/16,and then maintained 130.4 mA?h/g after 40 cycles in various rates at room temperature.