Tian Shuhao, Huang Juanjuan, Yang Hongcen, Liu Guo, Zeng Qi, Wang Di, Sun Xiao, Tao Kun, Liu Guohan, Peng Shanglong
School of Materials and Energy, National & Locai Joint Engineering Laboratory for Optical Conversion Materials and Technology, Lanzhou University, Lanzhou, 730000, P. R. China.
School of Physical Science and Technology, Lanzhou University, Lanzhou, 730000, P. R. China.
Small. 2022 Dec;18(48):e2205163. doi: 10.1002/smll.202205163. Epub 2022 Oct 25.
The low utilization rate of active materials, shuttle effect of lithium polysulfides (LiPSs), and slow reaction kinetics lead to the extremely low efficiency and poor high current cycle stability of lithium sulfur batteries (Li-S batteries). In this paper, a self-supporting multicomponent hierarchical network aerogel is proposed as the modified cathode (S/GO@MX@VS ). It consists of graphene (GO) and MXene nanosheets (MX) loaded with VS nanoparticles. The experimental results and first-principles calculations show that the GO@MX@VS aerogel has strong adsorption and reversible conversion effects on LiPSs. It can not only inhibit the shuttle effect and improve the utilization rate of active substances by keeping the chain crystal structure of VS , but also promote the reversibility and kinetics of the reaction by accelerating the liquid-solid transformation in the reduction process and the decomposition of insoluble Li S in the oxidation process. The GO@MX@VS aerogel modified cathode with a multicomponent synergy exhibits the capacity ratios (Q /Q ) at different discharge stages is close to the theoretical value (1:2.8), and the capacity decay per cycle is 0.019% in 1200 cycles at 5C. Also, a high areal capacity of 6.90 mAh cm is provided even at high sulfur loading (7.39 mg cm ) and low electrolyte/sulfur ratio (E/S, 8.0 µL mg ).
活性材料利用率低、多硫化锂（LiPSs）的穿梭效应以及缓慢的反应动力学导致锂硫电池（Li-S电池）的效率极低且高电流循环稳定性差。本文提出一种自支撑多组分分级网络气凝胶作为改性正极（S/GO@MX@VS ）。它由负载有VS纳米颗粒的石墨烯（GO）和MXene纳米片（MX）组成。实验结果和第一性原理计算表明，GO@MX@VS气凝胶对LiPSs具有强吸附和可逆转化作用。它不仅可以通过保持VS的链状晶体结构抑制穿梭效应并提高活性物质的利用率，还可以通过加速还原过程中的液-固转变和氧化过程中不溶性Li₂S的分解来促进反应的可逆性和动力学。具有多组分协同作用的GO@MX@VS气凝胶改性正极在不同放电阶段的容量比（Q₂/Q₁）接近理论值（1:2.8），在5C下1200次循环中每循环的容量衰减为0.019%。此外，即使在高硫负载量（7.39 mg cm⁻²）和低电解液/硫比（E/S，8.0 µL mg⁻¹）的情况下，也能提供6.90 mAh cm⁻²的高面积容量。
