哈工大张乃庆AEM：基于晶面工程策略设计高活性纳米催化剂助力高稳定锂硫电池

【研究背景】

锂硫（Li-S）电池因其高的理论能量密度而成为新一代能量存储与转换系统中最有前途的二次电池之一，受到了广泛的关注。在Li-S电池中，多硫化锂的吸附和转化都发生在催化剂的表面，然而，Li-S电池领域目前的大多数研究工作集中在通过对催化材料的体相的组成、微观结构和电子结构的设计及调控来优化电极的性能，忽视了不同的暴露晶面上的特殊的原子排列及原子配位环境对多硫化物的吸附及催化转化的重要影响。探索并揭示晶面效应在Li-S电池中的作用规律及深层次机理，对Li-S电池中表面催化过程的深入认识及高性能硫电极的理性设计具有重要意义。

【工作介绍】

近日，哈尔滨工业大学的张乃庆教授团队通过晶面工程策略调控SnO₂纳米晶催化材料的暴露晶面，合成了暴露{332}晶面的高催化活性SnO₂纳米八面体，系统研究了Li-S电池中的晶面效应。与{111}晶面的SnO₂纳米晶相比，{332}晶面具有丰富配位不饱的Sn原子，具有更高的吸附能力和催化活性，能够更有效地锚定多硫化物，促进其转化，同时显著降低了Li₂S的分解能垒，大幅度地提升了Li-S电池的倍率性能和循环稳定性。相关工作以“Crystal Facet Engineering Induced Active Tin Dioxide Nanocatalysts for Highly Stable Lithium-Sulfur Batteries”为标题发表在Adv. Energy Mater. 期刊上。

【文章图表】

图1 SnO₂ {332}-G和SnO₂ {111}-G的形貌、结构表征和元素分析及SnO₂ (332) and SnO₂ (111)晶面模型

Figure 1. a) SEM image of SnO₂ {332}-G, b, e) TEM images, c, f) corresponding SAED patterns, d, g) schematic models of SnO₂ {332} viewed along the [1(_)11] and [1(_)10] direction; h) HRTEM image of the selected region in (e). i) SEM image of SnO₂ {111}-G, j, m) TEM images, k, n) corresponding SAED patterns, l, o) schematic models of SnO₂ {111} viewed along the [001] and [101(_)] direction; p) HRTEM image of the selected region in (j). q) PXRD patterns and r) Sn 3d XPS spectra of SnO₂ {332}-G and SnO₂ {111}-G. s, t) Schematic models of SnO₂ (332) and SnO₂ (111) facets.

图2 Li₂S₄在不同SnO₂晶面上吸附的理论计算和吸附性能表征

Figure 2. a,b) Optimized geometries of Li₂S₄ adsorbed on different SnO₂ facets. c) UV–vis spectrums and corresponding optical photograph of a bare Li₂S₄ solution and the Li₂S₄ solutions with different materials after statical adsorption for 12 h. d) Sn 3d XPS comparative analysis of SnO₂ {332}-G and SnO₂ {111}-G after interacting with Li₂S₄.

图3 理论计算

Figure 3. a) DOS of Sn on SnO₂ (332) and SnO₂ (111) facets. b) Optimized geometries, c) decomposition energy barriers of Li₂S adsorbed on different SnO₂ crystal facets. Li₂S decomposition pathways on d) SnO₂ (332) and e) SnO₂ (111) facets.

图4 SnO₂ {332}-G, SnO₂ {111}-G和G的催化性能测试

Figure 4. a) CV curves and d) Nyquist plots of asymmetrical batteries with SnO₂ {332}-G, SnO₂ {111}-G and G. Tafel plots of the b) initial lithiation and c) delithiation process of asymmetrical batteries with SnO₂ {332}-G and SnO₂ {111}-G. e) CV curves of the symmetric batteries with SnO₂ {332}-G, SnO₂ {111}-G and G electrodes. f) Potentiostatic discharge profiles of Li₂S nucleation and g) Potentiostatic charge profile of Li₂S dissolution on SnO₂ {332}-G, SnO₂ {111}-G and G.

图5 SnO₂ {332}-G, SnO₂ {111}-G和G的电化学性能测试

Figure 5. a) Rate performance. b) Galvanostatic charge/discharge profiles and c) charge voltage profiles of SnO₂ {332}-G, SnO₂ {111}-G and G cells at 0.1 C. d) Cycle performance of SnO₂ {332}-G, SnO₂ {111}-G and G cells at 0.5 C. e) Long-term cycle stability of SnO₂ {332}-G and SnO₂ {111}-G cells at 2 C. f) Galvanostatic charge/discharge profile and g) cycling performance of SnO₂ {332}-G cell with high sulfur loading of 8.12 mg cm^-2 at 0.2 C (The sulfur content is 75 wt.%).

B. Jiang, Y. Qiu, D. Tian et al. Crystal Facet Engineering Induced Active Tin Dioxide Nanocatalysts for Highly Stable Lithium-Sulfur Batteries, Adv. Energy Mater. 2021, 2102995. https://doi.org/10.1002/aenm.202102995.