柔性多功能Fe_(2)O_(3)/CC正极宿主实现高效吸附与催化多硫化物的锂硫电池

A highly efficient absorptive and catalytic self-supporting Fe_(2)O_(3)/CC host for high performance Li-S batteries

锂硫电池因其高能量密度和低成本而成为最有发展前景的电化学储能器件之一。然而,多硫化物的“穿梭效应”、硫导电率低是锂硫电池商业化面临的主要挑战。本工作中,以Fe(NO)_(3)·9H_(2)O为铁源,NH4F为表面活性剂,通过简单的水热及煅烧处理制备了Fe_(2)O_(3)纳米棒修饰炭布(CC)的柔性Fe_(2)O_(3)/CC复合材料。其中,Fe_(2)O_(3)中介孔的存在有利于电解质的渗透和充放电过程中锂离子的传输和扩散,同时其密集阵列暴露出的丰富活性位点可以实现多硫化物的高效吸附和快速转化,降低多硫化物的穿梭效应。电化学分析显示:Fe_(2)O_(3)/CC正极在0.1 C(1 C=1672 mA g^(−1))的电流密度下具有1250 mAh g^(-1)的高放电比容量,经100圈循环后比容量保持在789 mAh g^(-1)。在2 C的倍率下循环1000圈后仍能达到576 mAh g^(-1)的放电比容量,容量保持率为70%,明显优于对比样品。因此,Fe_(2)O_(3)/CC能够很好地抑制多硫化物的穿梭,提高电池倍率性能和循环稳定性。

The lithium−sulfur(Li-S)battery is a promising energy storage system because of its high energy density and low cost.However,the shuttling of lithium polysulfides(LiPSs)and low conductivity of the S cathode are barriers to its practical application.Fe_(2)O_(3) nanorods were grown on a carbon cloth(Fe_(2)O_(3)/CC)by a solvothermal reaction and calcination to obtain a cathode for the battery.The mesoporous structure of the Fe_(2)O_(3) and the CC conducting network facilitates lithium-ion and electron transport.Meanwhile,the nanorod arrangement results in the exposure of more Fe_(2)O_(3) active sites,which improves the adsorption and rapid conversion of LiPSs.As a result,a Li–S cell using a Fe_(2)O_(3)/CC cathode has a high capacity of 1250 mAh g^(-1) at 0.1 C with an excellent life of over 100 cycles with a capacity retention of 67%.It also has a 70%capacity retention after 1000 cycles at 0.2 C.The excellent electrochemical performance of the Fe_(2)O_(3)/CC cathode indicates its potential applications in Li-S batteries.