湍流驱动合成石墨烯包覆的六方氮化硼粉末，用于无枝晶钾金属电池

摘要：钾金属电池被视为下一代储能系统的有前途候选方案。然而，其实际开发受限于容量输出不足及负极侧持续的枝晶增生问题。本文，北京石墨烯研究所刘忠范院士、孙靖宇教授、Yuqing Song等《ADVANCED MATERIALS》期刊发表名为“Turbulent Flo

1成果简介

钾金属电池被视为下一代储能系统的有前途候选方案。然而，其实际开发受限于容量输出不足及负极侧持续的枝晶增生问题。本文，北京石墨烯研究所刘忠范院士、孙靖宇教授、Yuqing Song等《ADVANCED MATERIALS》期刊发表名为“Turbulent Flow-Driven Synthesis of Graphene-Skinned Boron Nitride Heterostructures for Dendrite-Free Potassium Metal Batteries”的论文，研究通过流化床化学气相沉积法成功制备出石墨烯包覆的六方氮化硼粉末，实现了在h-BN基底上形成原子级耦合异质界面的层数可控（5-90层）石墨烯的共形生长。

对流化床反应器流态化环境的流体动力学模拟表明，局部湍流驱动的前驱体传输实现了粉末均匀流态化与石墨烯的均相形成。采用石墨烯包覆六方氮化硼粉末改性铝集流体制备的钾金属电极，展现出优异的循环稳定性（0.5 mA cm⁻²下达1050小时）及低成核过电位（

2图文导读

图1、Schematic illustrating the strategic design of Gr-skinned h-BN@Al current collector. The strategy is to prepare graphene-skinned h-BN powder by FB-CVD and utilize such powdery heterostructure for the surface modification of Al foil. The elevated surface energy of Gr-skinned h-BN@Al renders enhanced K affinity and stabilized K nucleation, thus ensuring dendrite-free K metal anodes.

图2、Preparation and characterizations of Gr-skinned h-BN. a) Representative SEM image of Gr-skinned h-BN powders (growth conditions: 520 sccm Ar, 400 sccm H2, 80 sccm CH4; 40 min; 1100°C). Inset: Typical Gr-skinned h-BN powder. b) Raman spectrum of Gr-skinned h-BN. Inset: Deconvoluted D band of graphene and E2g mode of h-BN. c) XRD patterns of pristine h-BN and Gr-skinned h-BN. d) Annular dark-field and e) bright-field cross sectional STEM image of graphene and h-BN. f) High-resolution STEM images of the highlighted areas in (e), with related FFT pattern of graphene and h-BN. EELS profiles of g) graphene and h) h-BN. i) EELS mappings show the distribution of C, B and N elements. j) High-resolution XPS C 1s spectrum of Gr-skinned h-BN.

图3、Growth behavior of graphene on h-BN by FB-CVD. a) AFM image of pristine h-BN, with related height profile (lower panel) along the white dotted line indicated in the upper panel. b) SEM images of Gr-skinned h-BN obtained at the growth time of ≈10, ≈20, ≈30, ≈35, ≈40, and ≈60 min (other growth conditions: 520 sccm Ar, 400 sccm H2, 80 sccm CH4; 1100°C). c) Domain size, d) Coverage and thickness evolution of graphene on h-BN with different growth time. e) Raman spectra of ten randomly selected Gr-skinned h-BN samples.

图4、CFD simulations of gas flow in fluidized bed. Fluidization state calculated at different gas velocities: a) 0.50 L min−1, b) 0.75 L min−1, and c) 1.00 L min−1. Inset: Gas flow path image of the highlighted area. d) Bed heights and gas contents at different gas velocities. e) Lateral gas residence time distribution at the highest bed position for different gas velocities. f) Decomposition efficiency of different carbon-active species in the presence of hydrogen under corresponding growth conditions in a fluidized bed (growth conditions: 520 sccm Ar, 400 sccm H2, 80 sccm CH4; 1100°C). g) Variation of surface pressure at different gas velocities. Cross sectional STEM image of Gr-skinned h-BN at h) 0.50 L min−1, i) 0.75 L min−1, and j) 1.00 L min−1, respectively.

图5、Electrochemical performances of K deposition based on modified current collectors. GBN materials were obtained at the different growth time (other growth conditions: 520 sccm Ar, 400 sccm H2, 80 sccm CH4; 1100°C). a) Surface energy values of different current collectors. b) Tafel plots of different current collectors. c) Comparison of activation energies. d) EIS profiles of different current collectors before cycle (Test temperature: 25°C). e) The distribution of relaxation times (DRT) based timescale diagnoses for different current collectors before cycle. f) Voltage−capacity profiles in asymmetric cell configuration at 0.5 mA cm−2. g) Comparison of Coulombic efficiency performances of different current collectors. h) Voltage−time profiles of symmetric cells showing K plating/stripping on different current collectors at 0.5 mA cm−2/0.5 mAh cm−2.

3小结

综上所述，我们提出一种基于流化床的高效质量/热传递特性实现石墨烯直接生长的FB-CVD方法，可实现均匀石墨烯包覆六方氮化硼粉末的可控批量生产。通过CFD模拟解析流化床内部流体动力学行为，阐明内部湍流如何支配气体流动轨迹与停留时间分布，从而验证气体流速对石墨烯质量的调控作用。利用石墨烯包覆六方氮化硼粉末增强的表面能，我们制备出GBN@Al集流体。由此制备的钾金属电极展现出优异的循环稳定性（0.5 mA cm⁻²条件下≈1050小时）和低成核过电位（

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