由超稳定碳负极支持的快速充电和长循环钠离子电池

摘要：实现具有卓越功率密度的快速充电钠离子电池（SIBs）是下一代电动汽车面临的关键挑战。目前，碳质负极被视为技术最成熟但受倍率限制的候选方案，正逐步走向商业化。为突破传统碳结构中离子传输缓慢和界面不稳定的瓶颈，本文，南开大学王庆伦副教授、焦丽芳教授等在《ADV

1成果简介

实现具有卓越功率密度的快速充电钠离子电池（SIBs）是下一代电动汽车面临的关键挑战。目前，碳质负极被视为技术最成熟但受倍率限制的候选方案，正逐步走向商业化。为突破传统碳结构中离子传输缓慢和界面不稳定的瓶颈，本文，南开大学王庆伦副教授、焦丽芳教授等在《ADVANCED MATERALS》期刊发表名为“Fast-Charging and Long-Cycle Sodium-Ion Batteries Enabled by an Ultra-Stable Carbon Anode”的论文，研究人员通过在空心碳球（CN@HCS）表面嵌入g-C3N4电子惰性层，设计出分级负极材料。该结构不仅促进Na⁺扩散，还能有效抑制副反应，同时实现电子的选择性屏蔽。该材料展现出卓越的倍率性能，在高达40 A g⁻¹的电流密度下仍保持高性能，并在超过40,000次循环中保持出色的循环稳定性，容量衰减可忽略不计。由此构建的完整电池可在0.1小时内实现快速充电，并具备长达1小时的持续放电能力，同时实现21600 W kg⁻¹（正负极总和）的高功率密度。这项工作标志着在锂离子电池先进负极材料研发领域取得重大突破。

2图文导读

方案一、Schematic illustration of the mechanism for the designed CN@HCS anode. The g-C3N4 is epitaxially grown and then coated onto HCS (CN@HCS). The primary objective is to reduce the degree of porous tortuosity of the original HCS and optimize the utilization of FEC, thereby obtaining a higher NaF content within the SEI, thus enhancing the kinetics and attaining superior stability.

图1、Structural characterizations and chemical state analysis. a) The preparation process of CN@HCS. b) The TEM image and the inset show the thickness of CN@HCS. c) HRTEM and the zoomed inverse fast Fourier transform image. d) SAED and elemental mapping for N and C elements. e) XRD patterns of HCS and CN@HCS. f) Raman spectra of HCS and CN@HCS. g) FT-IR of HCS and CN@HCS.

图2、Electrochemical performance evaluation. a) GCD curves and b) cycling performance for 200 cycles of HCS and CN@HCS at 0.1 A g−1. c) CV curves of CN@HCS from at scanning rates from 0.2 mV s−1 to 1.5 mV s−1. d) Rate capabilities of HCS and CN@HCS under various current densities from 0.1 to 40 A g−1. e) Long-term cyclic testing at 20 A g−1 for 40000 cycles. f) The CN@HCS anode in this work demonstrates outstanding cyclic life and rate capability for reversible Na storage compared with previous reports.+

图3、Electrochemical reaction mechanism of the hybrid electrode. a) In situ XRD pattern for the (002) diffraction peak and FT-IR spectrum for the C─N bonds of CN@HCS anode in the initial cycle. b,c) In situ FT-IR spectra of HCS and CN@HCS electrodes during the initial discharge process for: C─F bonds and poly- or oligo(ethylene carbonate) species. d) Gas release measured via the in situ DEMS experiments. e) Density of states for HCS and CN@HCS electrodes. f) Na transport paths in CN@HCS, and transport barriers of HCS and CN@HCS.+

图4、Characterizations of the SEI on HCS or CN@HCS anodes subsequent to cycling. a) 3D topographical AFM images of HCS and CN@HCS electrodes. b) TEM image of CN@HCS anode. c) HADDF and EDS mapping of CN@HCS anode. d) HRTEM images and SAED pattern of the SEI containing inorganic components for the CN@HCS. High-resolution XPS spectra of the SEI on CN@HCS anode: e) F 1s and f) Na 1s. g) The time evolution of the atomic ratios of C, F, O, Na, and Cl signals of the SEI on CN@HCS anode after different etching times.

图5、Exploration of electrochemical performance and application of full cells based on CN@HCS anode and NFPP cathode. a) Schematic representation of the CN@HCS||NFPP full cell. b) Charge–discharge profiles at 0.05 A g−1 for CN@HCS||NFPP full cell. c) Rate capability of CN@HCS||NFPP at various current densities from 0.05 to 8 A g−1. d) Long-cycling performance at 1 A g−1 for 3000 cycles. e) For the CN@HCS||NFPP full cell with other reported full cell configurations. f) Charge current density at 0.1 A g−1 and discharge rate current density at 1 A g−1, respectively. g) Exhibition of a 7-inch liquid crystal display (LCD) powered by a CN@HCS||NFPP pouch cell. h) The overall performance evaluation of full batteries featuring diverse anodes.

3小结

综上所述，碳纳米管@氢氧化钾硅酸盐（CN@HCS）负极在碳酸酯类电解液中实现了超长循环寿命与优异的倍率性能。通过热沉积在HCS表面形成的γ-C₃N₄，有效降低了过大的比表面积并屏蔽结构缺陷，从而抑制了电极/电解液间的不良副反应。CN@HCS表面的g-C3N4能高效促进FEC的吸附与还原，形成均匀、坚固且富含无机物的SEI层，从而减轻电解液消耗并提升FEC利用率。此外，g-C3N4中丰富的π共轭电子体系与负电荷中心为电荷传输提供了充足且快速的迁移通道。经合理设计的CN@HCS作为锂离子电池负极，在酯类电解液中展现出卓越的电化学性能，使集成CN@HCS||NFPP全电池具备超凡循环稳定性（在1 A g−1条件下经3000次循环后衰减率低于0.4%）。此外，其在快速充电阶段（0.1小时）和慢速放电阶段（1小时）均展现出潜在应用价值，且充放电效率接近100%。本研究为采用超长循环碳酸酯类电解液的碳基负极电极在锂离子电池领域的应用提供了新见解。

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