1成果简介
　　铋作为锂离子电池的合金型负极材料，具有高比容量和体积能量密度。然而，长期充放电循环导致的显著体积膨胀和容量衰减阻碍了其商业化应用。本文，哈尔滨理工大学刘刚 教授、冯义成 教授、哈尔滨工业大学王东博 研究员、赵连城 院士等在《Materials Today Physics》期刊发表名为“Lasagne-like Bi2O3/Bi dual-carbon composites for high-capacity and long-life lithium storage”的论文，研究构建了具有类似千层饼结构的石墨烯-非晶碳层双涂层Bi₂O₃/Bi复合材料（Gr@Bi₂O₃/Bi@AC）作为锂离子电池负极。
　　Bi₂O₃的引入不仅促进锂离子吸附，还通过转化反应缓解体积波动。多层石墨烯显著提升比表面积并增强离子/电子传输效率，而与非晶碳的结合则形成强韧的双层保护结构，确保材料完整性。由此，Gr@Bi₂O₃/Bi@AC负极展现出高初始库仑效率（69.3%）、卓越的倍率性能（2000 mA g⁻¹下达466 mAh g⁻¹）及优异的长期循环稳定性（500次循环后500 mA g⁻¹下仍保持1012.1 mAh g⁻¹）。本研究通过优化双碳层结构与多组分协同工程，为解决铋基材料容量衰减问题提供了创新设计方案。所得结论将为设计兼具高容量与稳定性的负极材料开辟全新路径。
　　2图文导读 

　　图1. Schematic illustration of the preparation of Gr@Bi2O3/Bi@AC.

　　图2. (a) SEM, (b) TEM, and (c) HRTEM image of BOT. (d) SEM, (e) TEM, and (f) HRTEM image of BOC. (g) SEM, (h) TEM, and (i) HRTEM image of BCL. (j) EDS image of BCL and elemental mappings of (k) Bi, (l) O, (m) C, (n) N. (o) X-ray diffraction patterns of BOT, BOC, and BCL.

　　图3. (a) N2 adsorption/desorption isotherm (the illustration is the pore size distribution curve of BOT, BOC, and BCL). (b) Full XPS spectrum of BCL, the corresponding high-resolution spectrum of (c) C 1s, (d) Bi 4f, (e) O 1s, and (f) N 1s.

　　图4. CV curves of (a) BCL, (b) BOC, and (c) BOT at a scan rate of 0.1 mV s-1 for the first 3 cycles. (d) Cycling performance of BOT, BOC, and BCL at 200 mA g-1. (e) Rate capabilities from 500 to 2000 mA g-1. (f) Constant current charge-discharge curves of BCL cycled at different current densities. (g) Long-term cycling comparison of BOT, BOC, and BCL at 500 mA g-1. (h) Galvanostatic charge-discharge profiles of BOT, BOC, and BCL for the five hundredth cycle at 500 mA g-1.

　　图5. (a) CV characteristics of BCL at scanning rate from 0.1 to 1.0 mV s-1. (b) b values. (c) EIS spectra of the BOT, BOC, and BCL electrodes. (d) Rel, Rct values of the BOT, BOC, and BCL electrodes in fresh LIBs. (e) EIS curves of different cycles. (f) EIS high-frequency zone curves for different cycles. (g) Linear relations of Z′ vs ω−1/2 for BCL electrode after different numbers of cycles. (h) GITT profiles of BOT, BOC, and BCL at 0.01-3 V. (i) Diffusion coefficients of Li ions for BOT, BOC, and BCL during lithiation.

　　图6. CV characteristics of BCL at 0.2 to 1.0 mV s-1 scan rates after (a) 100, (b) 200, and (c) 300 cycles at the current density of 500 mA g-1. Capacitance contribution plots after (d) 100, (e) 200, and (f) 300 cycles at a scan rate of 1.0 mV s-1. Capacitance contribution at different scan rates after (g) 100, (h) 200 and (i) 300 cycles.
　　3小结
　　在本研究中，证明了多层Gr@Bi₂O₃/Bi@AC复合材料作为锂离子电池的极具前景的电极材料。Bi₂O₃/Bi纳米球混合结构通过Bi²⁺O₃→Bi转化反应，在充放电过程中减缓了铋与锂的合金化速率，从而缓解了电极材料的体积膨胀。丰富的Bi₂O₃在长期循环中还充当铋的长期储库，有助于提升电极的可逆容量。精心设计的双缓冲碳层富含缺陷，提供充足的内部空间、大量锂储存活性位点及高效的离子/电子传输效率，并与Bi₂O₃转化反应协同作用，有效抑制铋基材料合金化/去合金化过程中的体积膨胀。Gr@Bi₂O₃/Bi@AC电极展现出卓越的锂存储性能，在0.5 A g⁻¹条件下经500次循环后仍保持1012.1 mAh g⁻¹的高可逆容量，容量保持率达87.8%。在2 A g⁻¹条件下经2000次循环后，其容量仍达246.8 mAh g⁻¹，超越先前报道的铋基合金型负极材料。这彰显了双碳层封装技术的广阔应用前景，为开发高性能负极材料以满足高容量锂离子电池日益增长的需求开辟了新路径。
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