纳米Au-氮掺杂碳纳米管一体化复合正极的构筑及锂氧气电池性能

Construction of nano Au-nitrogen doped carbon nanotubes integrated composite cathode and performance study for lithium-oxygen batteries

  • 摘要: 高效稳定的正极对锂氧气电池至关重要。通过化学气相沉积、光还原两步合成工艺,将具有高催化活性的Au纳米粒子原位负载在具有三维贯穿结构的氮掺杂碳纳米管(N-CNT)/不锈钢(SS)网上,制备了具有互相渗透孔道的高性能一体化锂氧气电池正极Au-N-CNT/SS。通过SEM、TEM、XPS、XRD及Raman等表征手段对Au-N-CNT/SS的微观形貌、组成进行了考察。制备的Au-N-CNT/SS正极具有合适的孔道结构、高电导率、超强的力学性能、结构稳定性等,克服了传统电极机械稳定性差、碳电极易分解、副反应严重等问题。用作锂氧气电池正极,Au-N-CNT/SS一体化电极的设计避免了黏结剂的使用,极大地提高了电池的力学强度,有效降低了副反应,提升了电池的电化学/化学稳定性;正极的高导电率、充足的孔道结构提供了快速的电子输运和传质通道;Au纳米粒子高效催化剂有效提升了正极的氧还原/氧析出反应动力学,加快了放电产物的生成与分解,电池的倍率性能(1.0 mA·cm−2的高电流密度下放电电压保持在2.4 V)、放电容量(8.47 mA·h·cm−2)和循环性能(160圈)得到了较大提升。

     

    Abstract: Highly efficient, stable cathode is crucial to lithium-oxygen battery. A high performance, integrated Au-N-CNT/SS cathode with interpermeable channels was constructed by chemical vapor deposition and photoreduction, in which the high catalytic Au nanoparticles were loaded on nitrogen doped carbon nanotubes (N-CNT) with three-dimensional penetrating sturctured stainless steel (SS) mesh. The morphology and composition of the Au-N-CNT/SS were investigated by SEM, TEM, XPS, XRD and Raman spectrum. The problems of poor mechanical stability, carbonaceous cathode decomposition and serious side reactions were avoided by the suitable channel structure, high conductivity, superior mechanical properties, structural stability of Au-N-CNT/SS. Taking Au-N-CNT/SS as the integrated cathode for lithium-oxygen battery, the utilization of binder is avoided. The mechanical strength of the lithium-oxygen battery is enhanced, and the side reactions are effectively reduced, contributing to the enhanced electrochemical/chemical stability. The high conductivity, interpenetrated structure and sufficient pores provide a fast electron transport and mass transfer channel. The highly efficient Au nanoparticles are favorable to improving the oxygen reduction/oxygen evolution reaction kinetics on cathode, accelerating the generation and decomposition of discharge products. The rate performance (keeping the discharge voltage at 2.4 V with a high current density of 1.0 mA·cm−2), specific capacity (8.47 mA·h·cm−2) and cycle performance (160 cycles) of lithium-oxygen battery are greatly improved.

     

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