1成果简介
　　电动汽车行业的指数级增长迫切需要快速发展锂离子电池的快充技术。然而，主流石墨负极在快充场景下面临显著挑战，包括因缓慢的锂化动力学和不稳定的固态电解质界面导致的容量衰减和寿命缩短。本文，中国科学院大连化学物理研究所石浩东 副研究员、吴忠帅 研究员等在《ADVANCED MATERIALS》期刊发表名为“Kilogram-Scale Production of Ultrafast-Charging Micro-Expanded Graphite Anode toward High-Power and Long-Life Ah-Level Pouch Batteries”的论文，研究报道了千克级可扩展生产的超快充电阳极（C@MEG），其由微膨胀石墨涂覆超薄无序碳层（5nm）构成，该结构同时弥补了传统内部锂扩散动力学的局限性，并重新配置了外部电极-电解质界面。这种独特性赋予了快速的表面到体积锂传输，同时最小化了电极极化，增强了伪电容行为，并降低了界面阻抗。
　　在10C的超快充电速率下，该Li||C@MEG电池展现出157mAh g−1的超高容量，优于原始石墨（71mAh g−1）和先前报道的石墨负极。此外，该组装的1 Ah级C@MEG||LiCoO₂软包电池展现出卓越的快速充电循环性能，在3 A充电电流下经过1000次循环后仍保持92%的容量，同时在10 A充电电流下实现约1500W kg−1 的高功率密度，对应仅需4.2分钟的短充电时间，充分证明了其应用潜力。本研究提出了一种实用且可扩展的快速充电阳极，适用于高能量密度、高功率密度和长寿命电池。
　　2图文导读 

　　图1、Morphological and structural characterizations of C@MEG material. a) Schematic diagram illustrating the preparation of C@MEG. b–d) SEM images of b) NG, c) MEG and d) C@MEG. e–g) HRTEM images of e) NG, f) MEG, and g) C@MEG. h) XRD patterns, i) Raman spectra, and j) C 1s XPS spectra of NG, MEG, C@NG, and C@MEG materials.

　　图2.Electrochemical reactions and performance of Li||graphite-based coin-type cells. a) CV curves of NG and C@MEG obtained at 0.05 mV s−1. b) dQ/dV plots of NG and C@MEG tested at 0.1 C. c,d) GCD profiles of c) NG and d) C@MEG. e) Rate performance from 0.1 to 10 C. f) Comparison of rate capability of C@MEG with recently reported graphite anodes. g) Long-term cyclability at 3 C, h) EIS curves and corresponding DRT profiles after cycling for NG, MEG, C@NG and C@MEG.

　　图3、Kinetic analysis of the electrochemical behavior of the C@MEG anode. a,c) The in situ XRD patterns of a) MEG and c) C@MEG. b,d) The in situ EIS of b) MEG and d) C@MEG. e) lithium diffusion and f) ohmic polarization at different lithiation|delithiation depths illustrated from GITT curves. g) CV curves of NG and C@MEG obtained at various scan rates ranging from 0.1 to 2.0 mV s−1. h) Comparison of b-values and i) capacity contribution ratio in capacitance and diffusion-controlled processes at different scan rates for NG, MEG, C@NG and C@MEG.

　　图4、Interface characteristics between electrode and electrolyte after cycles at 3 C. a) F 1s and b) C 1s XPS spectra of the SEI formed on NG and C@MEG electrodes at different Ar sputter durations (0 s, 90 s, and 180 s). c) 3D reconstruction models illustrating the distribution of C+6−, LiF2−, PO2−, LiO−, C2H2O−, and d) corresponding 2D overlay mapping images of LiF2− and C2H2O− obtained from TOF-SIMS of the SEI layer formed on NG, MEG and C@MEG. e) TEM and f) SEM images of NG, MEG and C@MEG electrodes. g) The activation energies derived from the charge transfer impedance.

　　图4、Surface-to-bulk lithium transport and SEI formation of C@MEG, and its application in Ah-level full batteries. a,b) Schematic illustration showing the positive impact of b) C@MEG's structure and composition on lithium transport and high-quality SEI formation, compared to a) NG. c) Rate capability and d) long-term cyclability of 1 Ah C@MEG||LiFePO4 pouch battery obtained at 3 A. e) Rate capability and f) long-term cyclability of 1 Ah C@MEG||LiCoO2 pouch battery measured at 3 A.
　　3小结
　　综上所述，我们提出了一种表面-体相协同调控策略，实现了高容量、快充型C@MEG负极材料的公斤级规模化生产，该材料兼具快速表面相假电容特性与高体相插层容量。本研究通过优化石墨负极与电解液的界面设计，提升石墨层中锂离子的插层效率，并促进石墨颗粒间锂离子的传输，从而通过石墨材料设计策略提升电化学性能。该策略旨在克服传统插层型锂储存行为的局限性，增强二维结构中的离子扩散路径，并抑制石墨中的不利副反应，从而同时实现高容量、快速充电和长寿命。我们的C@MEG电池通过优化表面无序碳涂层（厚度5 nm）与内部微膨胀石墨的结构，可有效平衡斜率容量与平台容量，实现稳定电极-电解质界面上的快速电荷转移及石墨体相内的锂离子传输。因此，Li||C@MEG电池展现出卓越的倍率性能，在10C倍率下可实现157 mAh g−1的高可逆容量。研究的1Ah级软包电池在C@MEG||LiFePO4和C@MEG||LiCoO2体系中均具备快速充放电能力和长期循环稳定性，彰显了其广泛适用性。因此，我们的C@MEG负极设计为实现高能量密度、高功率和长寿命的商业化锂离子电池（LIBs）提供了可行的可扩展路径。
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