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Enhancing Polysulfide Confinement and Electrochemical Kinetics by Amorphous Cobalt Phosphide for Highly Efficient Lithium–Sulfur Batteries
ACS Nano ( IF 15.8 ) Pub Date : 2020-12-28 , DOI: 10.1021/acsnano.0c07038 Rui Sun 1, 2 , Yu Bai 1, 2 , Min Luo 1, 2 , Meixiu Qu 1, 2 , Zhenhua Wang 1 , Wang Sun 1 , Kening Sun 1
ACS Nano ( IF 15.8 ) Pub Date : 2020-12-28 , DOI: 10.1021/acsnano.0c07038 Rui Sun 1, 2 , Yu Bai 1, 2 , Min Luo 1, 2 , Meixiu Qu 1, 2 , Zhenhua Wang 1 , Wang Sun 1 , Kening Sun 1
Affiliation
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The application of lithium–sulfur (Li–S) batteries is severely hampered by the shuttle effect and sluggish redox kinetics. Herein, amorphous cobalt phosphide grown on a reduced graphene oxide-multiwalled carbon nanotube (rGO-CNT-CoP(A)) is designed as the sulfur host to conquer the above bottlenecks. The differences between amorphous cobalt phosphide (CoP) and crystalline CoP on the surface adsorption as well as conversion of lithium polysulfides (LiPSs) are investigated by systematical experiments and density-functional theory (DFT) calculations. Specifically, the amorphous CoP not only strengthens the chemical adsorption to LiPSs but also greatly accelerates liquid-phase conversions of LiPSs as well as the nucleation and growth of Li2S. DFT calculation reveals that the amorphous CoP possesses higher binding energies and lower diffusion energy barriers for LiPSs. In addition, the amorphous CoP features reduced energy gap and the increased electronic concentrations of adsorbed LiPSs near Fermi level. These characteristics contribute to the enhanced chemisorption ability and the accelerated redox kinetics. Simultaneously, the prepared S/rGO-CNT-CoP(A) electrode delivers an impressive initial capacity of 872 mAh g–1 at 2 C and 617 mAh g–1 can be obtained after 200 cycles, exhibiting excellent cycling stability. Especially, it achieves outstanding electrochemical performance even under high sulfur loading (5.3 mg cm–2) and lean electrolyte (E/S = 7 μLE mg–1S) conditions. This work exploits the application potential for amorphous materials and contributes to the development of highly efficient Li–S batteries.
中文翻译：
非晶态钴磷增强高效锂硫电池的多硫化物限制和电化学动力学
穿梭效应和缓慢的氧化还原动力学严重阻碍了锂硫（Li-S）电池的应用。在此，将在还原的氧化石墨烯-多壁碳纳米管（rGO-CNT-CoP（A））上生长的非晶态磷化钴设计为硫主体，以克服上述瓶颈。通过系统实验和密度泛函理论（DFT）计算，研究了非晶态磷化钴（CoP）和结晶态CoP在表面吸附以及多硫化锂（LiPSs）转化率方面的差异。特别地，无定形CoP不仅增强了对LiPS的化学吸附，而且极大地加速了LiPS的液相转化以及Li 2的成核和生长。S. DFT计算表明，非晶态CoP对LiPS具有更高的结合能和更低的扩散能垒。此外，非晶态CoP的特征是能隙减小，费米能级附近的LiPS吸附电子浓度增加。这些特性有助于增强化学吸附能力和加速氧化还原动力学。同时，制备的S / rGO-CNT-CoP（A）电极在2 C时可提供令人印象深刻的872 mAh g –1的初始容量，经过200次循环可得到617 mAh g –1，具有出色的循环稳定性。尤其是，即使在高硫负荷（5.3 mg cm –2）和稀薄电解质（E / S= 7μL Ë毫克-1小号）的条件。这项工作开发了非晶材料的应用潜力，并为开发高效的Li–S电池做出了贡献。
更新日期：2021-01-26
中文翻译：
非晶态钴磷增强高效锂硫电池的多硫化物限制和电化学动力学
穿梭效应和缓慢的氧化还原动力学严重阻碍了锂硫（Li-S）电池的应用。在此，将在还原的氧化石墨烯-多壁碳纳米管（rGO-CNT-CoP（A））上生长的非晶态磷化钴设计为硫主体，以克服上述瓶颈。通过系统实验和密度泛函理论（DFT）计算，研究了非晶态磷化钴（CoP）和结晶态CoP在表面吸附以及多硫化锂（LiPSs）转化率方面的差异。特别地，无定形CoP不仅增强了对LiPS的化学吸附，而且极大地加速了LiPS的液相转化以及Li 2的成核和生长。S. DFT计算表明，非晶态CoP对LiPS具有更高的结合能和更低的扩散能垒。此外，非晶态CoP的特征是能隙减小，费米能级附近的LiPS吸附电子浓度增加。这些特性有助于增强化学吸附能力和加速氧化还原动力学。同时，制备的S / rGO-CNT-CoP（A）电极在2 C时可提供令人印象深刻的872 mAh g –1的初始容量，经过200次循环可得到617 mAh g –1，具有出色的循环稳定性。尤其是，即使在高硫负荷（5.3 mg cm –2）和稀薄电解质（E / S= 7μL Ë毫克-1小号）的条件。这项工作开发了非晶材料的应用潜力，并为开发高效的Li–S电池做出了贡献。
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