具有微纳结构的FeS_2的制备及其储锂性能研究

金属硫化物具有较大的理论容量,有望成为下一代的锂电池负极材料,但是充放电过程中材料发生严重的膨胀/收缩、晶体粉化,使得材料的比容量迅速衰减.本文以铁醇盐为原料制备具有花状微纳结构的FeS_2,以达到抑制材料粉化效果.结果显示,300℃热处理得到的FeS_2样品能够充分保持中间体铁醇盐的花状微纳结构,结晶度高.450℃处理得到的样品表面为多孔状结构,而800℃处理未得到目标产物,样品分子式是Fe_9S_(10).电化学测试结果表明:300℃所得产物具有1 484.3mA·h/g的放电比容量,高于450℃的产物(1 326.7mA·h/g);在电流密度为200mA/g条件下,100次充放电循环后,300℃所得产物的放电比容量为480.8mA·h/g,远高于450℃所得产物的放电比容量(215.8mA·h/g).研究结果表明具有花状微纳结构对材料的粉化现象有较好的抑制作用.

Synthesis of FeS_2 materials with micro/nano structure and their Lithium storage performances

Transition metal sulfide presents a big theoretical capacity,which might be one of anode materials of the next generation Li-ion battery.However,its capacity would suffer a sudden decrease due to the particle powdering,as the result of the serious expansion/contraction of electrode material during the charge/discharge process.Here three samples of iron/sulfur materials were prepared by sintering the flower-like micro/nano structural iron alkoxides under a mixed N_2 and H_2S atmosphere at 300,450 and 800 ℃.The results showed the sample sintered at 300 ℃ was with the structure of FeS_2,which maintained the morphology of iron alkoxides precursor and showed a well crystalline.Sample obtained at 450 ℃ was also with the structure of FeS_2.The surface of nanosheets within the sample exhibited a porous structure.Unfortunately,sample sintered at 800 ℃ was proved to be Fe_9S_(10).Results of electrochemical tests showed that FeS_2 obtained under 300 ℃ exhibited an initial discharge capacity of 1 484.3 mA·h/g at 200 mA/g,higher than that of the other samples at 450 ℃(1 326.7 mA·h/g).More importantly,after 100 times charge/discharge cycles(200 mA/g),sample prepared under 300℃showed a discharge capacity of 480.8 mA·h/g,which was far more than the sample sintered at 450 ℃(215.8 mA·h/g).The results in this paper proved that it could be an effective way to inhibit the particle powdering by designing a flower-like micro/nano structural FeS_2.