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文 章 信 息
镓调制 d–p 轨道耦合的高熵金属磷化物用于增强锂硫电池
第一作者:邱可柔
通讯作者:朱金良*
单位:广西大学
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研 究 背 景
锂硫电池具有理论能量密度高、硫资源丰富、环境友好等优点,是最有前景的下一代储能技术之一。然而,缓慢的硫电化学反应和可溶性多硫化物穿梭效应会导致硫利用率低和容量快速衰减。近期,电催化策略加速硫反应动力学成为有效抑制多硫化物穿梭的重要手段。
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文 章 简 介
近日,来自广西大学的朱金良教授在国际知名期刊Advanced Functional Materials上发表题为“Modulating d–p Orbital Coupling via Gallium in High-Entropy Metal Phosphides for Enhanced Lithium–Sulfur Batteries”的研究文章。该研究文章成功合成了优化的高熵磷化物 Fe0.5Co0.7Ni0.5Cu0.3Ga0.1P(Ga-HEP),通过P区金属镓调控高熵金属磷化物的d-p耦合。这项工作不仅为设计高熵金属磷化物提供了新策略,也为开发锂硫电池中高效的LiPS转化催化剂开辟了新途径。
1. Ga-HEP在电化学过程中促进多硫化物电催化转化行为
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本 文 要 点
要点一:P区金属镓对Ga-HEP的d-p耦合调控
镓掺入高熵相通过显著改变材料的电子结构,有效提升了对多硫化锂的催化转化性能。电子局域函数分析表明,Ga原子周围电子局域化增强,并与邻近原子形成更强的电子共享区域。这不仅使d-p轨道能隙缩小,还驱动d带中心上移了。根据d带中心理论,这一上移强化了材料与硫物种p电子的相互作用,从而增强了轨道杂化与电荷转移,促进了S-S键的断裂。同时,费米能级附近的高电子态密度和构型熵增加带来的更多活性位点,共同提升了材料的电子迁移能力和吸附容量,最终协同加速了多硫化锂的转化动力学。
Figure 1. a) Schematic illustration of the synthesis mechanism of Ga-HEP/PC. b) SEM image, c) TEM image and d) particle size distribution of Ga-HEP/PC. e) EDS elemental mapping of Ga-HEP. f, h) ADF–STEM images of Ga-HEP (insets show the corresponding FFT images) and g, i) the corresponding atomic stress-strain distributions. j) Atomic-level elemental mapping of Ga-HEP.
Figure 2. Theoretical studies of Ga-HEP, MEP, and GaP models for the sulfur reduction reaction. a) ELF model of Ga-HEP (left) and its cross-sectional view (right). b) ELF of MEPc) ELF of GaP. d) Density of states (DOS) of Ga-HEP. e) Schematic illustration of d-p orbital gaps and their comparison between Ga-HEP and MEP. f-g) Visual adsorption and corresponding UV absorption spectra of Ga-HEP/PC, MEP/PC, Mix/PC, GaP/PC, and PC. h) Calculated adsorption energies of LiPSs on Ga-HEP, MEP, and GaP. i–j) Charge density variation upon Li2S6 adsorption on Ga-HEP and MEP. k) Gibbs free energy diagram of the sulfur reduction reaction on Ga-HEP, MEP, and GaP.
要点二:P区金属镓调控的Ga-HEP促进多硫化物电催化转化
镓的掺入通过优化高熵相电子结构,增强d-p轨道杂化并上移d带中心,从而表现出快速的氧化还原动力学,有效抑制了多硫化物的穿梭效应,提高了硫的利用率。此外,结合原位电化学阻抗谱结合弛豫时间分布分析,全面研究 Ga-HEP 在充放电过程中复杂的电化学动力学行为和 LiPS 转化机制。
Figure 3. a) CV profiles of symmetrical cells with Ga-HEP/PC, MEP/PC, Mix/PC, and GaP/PC at a sweep rate of 1.0 mV s–1. b) LSV curves and c) corresponding Tafel plots for Ga-HEP/PC, MEP/PC, Mix/PC, and GaP/PC. Potentiostatic discharge profiles of Li2S nucleation at 2.12 V on different electrodes: d) Ga-HEP/PC, e) MEP/PC, and f) GaP/PC. Dimensionless transient curves (symbols) for g) Ga-HEP/PC, h) MEP/PC, and i) GaP/PC compared with theoretical 2D and 3D models, with corresponding SEM images shown in the insets.
Figure 4. a) CV curves of Ga-HEP/PC@S, MEP/PC@S, Mix/PC@S, and GaP/PC@S at a sweep rate of 0.1 mV s–1. b) Corresponding reaction peak voltages. c) Calculated polarization voltages. d–f) Tafel plots for peaks 1, 2, and 3, respectively. g) CV curves of Ga-HEP/PC@S at sweep rates from 0.1 to 0.4 mV s–1. h, i) Plots of CV current values for peaks 1 and 2 versus the square root of the scan rates.
Figure 5. In situ EIS evolution of a) Ga-HEP/PC@S and b) MEP/PC@S cathodes at different voltages, along with the corresponding 2D intensity color maps of DRT calculated from EIS. DRT curves for c) Ga-HEP/PC@S and d) MEP/PC@S, corresponding to the intensity color maps at various discharge/charge states. GITT voltage profiles of e) Ga-HEP/PC@S and f) MEP/PC@S. g) Internal resistances of Ga-HEP/PC@S and MEP/PC@S.
要点三:P区金属镓调控的Ga-HEP表现优异的的电化学能力
配备 Ga-HEP/PC@S 阴极的电池在 0.2 C下具备 1258.33 毫安时g−1的优异比容量,具有超高循环稳定性,在 5 C下 600 次循环后,比衰率仅为 0.020%。值得注意的是,配备 Ga-HEP/PC@S 阴极的 Li–S 软包电池能提供高能量密度 403.61 Wh kg−1。
Figure 6. a) Cycling performance and b) galvanostatic charge/discharge profiles of various cathodes at 0.2 C. c) ΔE and QL/QH values derived from b). d) Rate performance from 0.2 C to 5 C. e) Long-term cycling performance at 2 C. f) Performance radar chart of Ga-HEP/PC@S cathode compared with recently reported works. g) Long-term cycling performance at 5 C. h) Cycling performance of cathodes with high sulfur loading (4.5 mg cm–2) at 0.2 C. i) Cycling performance of a Li–S pouch cell with Ga-HEP/PC@S cathode and its digital photograph at 0.05 C.
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文 章 链 接
Modulating d–p Orbital Coupling via Gallium in High-Entropy Metal Phosphides for Enhanced Lithium–Sulfur Batteries
https://doi.org/10.1002/adfm.202523798
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通 讯 作 者 简 介
朱金良教授简介:广西大学资源环境与材料学院教授,广西八桂青年拔尖人才。主要从事锂硫电池和电催化剂材料研究,主持国家自然科学基金、广西自然科学基金及企业横向项目等多项,作为第一/通讯作者在Advanced Functional Materials等期刊上发表SCI论文80余篇,ESI高被引论文6篇,作为第一发明人授权国家发明专利3项。曾获广西重要技术标准奖励(排名三),广西科学技术自然科学类一等奖(排名三)和中国发明协会创业创新奖二等奖(排名二)。
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