中空碳球负载的镍铁双金属单原子催化剂用于高性能锂硫电池研究

Study on Ni-Fe bimetallic single-atom catalyst loaded on hollow carbon spheres for high-performance lithium-sulfur batteries

锂硫电池(lithium-sulfur battery,LSBs)是一种基于多电子转化反应机制的新型锂离子二次电池,具有能量密度高、环境友好、成本低廉的优点。然而,多硫化物的穿梭现象和硫正极反应动力学缓慢限制了LSBs的实用性。设计了一种负载镍铁双金属单原子催化剂的多孔空心碳球(NiFe-HCS)用作高效的硫载体纳米反应器。NiFe-HCS具有高比表面积,可以实现高的硫载量,且其空腔结构可以缓冲硫的体积膨胀。原子级Ni与Fe提供了丰富的化学吸附位点,不仅能够通过强的物理束缚和化学吸附能力抑制多硫化物的溶解和扩散,而且能够提高硫的利用率,促进多硫化物的反应还原动力学,有效地提高其催化转化效率。因此,基于NiFe-HCS纳米反应器的LSBs实现了高比容量、高倍率性能和超长的循环稳定性,在2 C电流密度下初始的质量比容量为1002 mAh/g,经过500次循环,电容量保持率为94%,并且在8 C电流密度下表现出优异的高倍率性能,质量比容量为932 mAh/g,显示了此纳米反应器在高能量密度锂硫电池中的巨大应用潜力。

Lithium-sulfur batteries(LSBs)are a new type of lithium-ion secondary battery based on a multi-electron conversion reaction mechanism.It has the advantages of high theoretical energy density,environmental compatibility,and cost-effectiveness.However,the shuttle effect of soluble polysulfides and sluggish electrochemical kinetics at the sulfur cathode limit the practicality of LSBs.A NiFe bimetallic single-atom catalyst supported on hollow carbon spheres(NiFe-HCS)was designed to serve as an efficient sulfur host and nanoreactor.NiFe-HCS features a high specific surface area,allowing for a high sulfur loading capacity,and its hollow structure can accommodate the volume expansion of sulfur.The atomic-level NiFe provides abundant chemical adsorption sites,which not only inhibit the dissolution and diffusion of polysulfides through strong physical confinement and chemical adsorption but also enhance sulfur utilization and promote the reduction reaction kinetics of polysulfides,thereby effectively improving catalytic conversion efficiency.As a result,LSBs based on the NiFe-HCS nanoreactor achieve high specific capacity,excellent rate performance,and ultra-long cycling stability.At a current density of 2 C,the mass specific capacity reaches 1002 mAh/g,with a capacity retention ratio of 94%after 500 cycles.Additionally,the battery exhibites excellent high-rate performance,delivering a mass specific capacity of 932 mAh/g at curvent density of 8 C.These results demonstrate the significant potential of this nanoreactor in high energy density lithium-sulfur batteries.