钾离子电池先进阻燃电解质：石墨负极的高稳定储钾 | Science Bulletin

Original 梁皓杰，吴兴隆等 ScienceBulletin 2022-10-01

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#电解质 2 个

#电池 33 个

#物质科学 53 个

Science Bulletin, 2022, 67(15): 1581-1588

https://doi.org/10.1016/j.scib.2022.07.002

Progress and perspective on the growth of two-dimensional single crystals

钾离子电池先进阻燃电解质: 石墨负极的高稳定储钾

梁皓杰, 谷振一, 赵欣欣, 郭晋芝, 杨佳霖, 李文灏, 李苞, 刘治明, 孙中辉, 张景萍, 吴兴隆*

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研究简介

在钾离子电池石墨负极中, 钾离子在石墨层间嵌入/脱出的模式能够实现储能, 且具有较低工作电位和廉价等优势, 表现出巨大的吸引力. 然而, 在缺乏足够界面保护等条件下, 石墨负极在传统碳酸酯类电解液中容易发生连续的副反应, 充放电容量会面临严重的持续衰减.

本文从电解液设计的角度出发, 针对石墨负极的钾离子存储问题, 配制了阻燃的局部高浓度电解液, 其特有的溶剂化结构可调控石墨表面固体电解质界面相, 改善界面的结构稳定性和离子传导特性, 从而实现石墨负极储钾的高稳定循环. 同时, 电解液的高阻燃特性也为钾离子电池的高安全性提供了保障.

图文导读

Fig. 1. Analyses of intrinsic component properties and overall functional testing.

(a) Frontier molecular orbital involving the lowest unoccupied molecular orbital (LUMO) and the highest occupied molecular orbital (HOMO) energy levels diagram of different solvents and salt.

(b) Binding energy for KFSI with TEP and TTE under

DFT calculation, indicating the stronger interaction of TEP with K⁺.

(c–e) Wettability and flame tests using glass fiber separators soaked with different electrolytes.

Fig. 2. Theoretical simulations and characterizations for the electrolyte.

(a) Snapshot for the 1.13 mol kg^-1 KFSI-TEP/TTE, enlarged solvation environment from regions 1 and 2, and corresponding simplified solvation models.

(b) K⁺ RDF obtained from simulations.

(d) Raman spectra corresponding to different electrolytes and solo solvent components. Regrettably, the characteristic peaks of TEP and FSI^- coincide (700–750 cm^-1), hindering

further FSI^- fitting in CIPs and AGGs.

Fig. 3. Electrochemical properties of graphite anode in K-ion half cells.

(a) GCD curves of the initial five cycles at 0.05 A g^-1 in the 1.13 mol kg^-1 KFSI-TEP/TTE electrolyte.

(b) CV curves at 0.02 mV s^-1.

(c) Cycling performance of graphite tested in K-ion half cells with different electrolytes (inset: CE for the preceding 20 cycles).

Fig. 4. Analyses and characterizations of the SEI layer.

(a) High-resolution XPS spectra (F 1s) for SEI on the surface of the graphite anode after 50 cycles in different electrolytes.

(b) S 2p, (c) N 1s, and (d) P 2p XPS spectra in 1.13 mol kg^-1 KFSI-TEP/TTE electrolyte.

(e) Morphology characterization by HRTEM.

(f) Evolution of the interfacial resistance of the graphite half cells from pristine to 300 cycles.

Fig. 5. Schematic diagram of the optimized electrolyte structure and constructed SEI.

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