二氟磷酸钾作为钾离子电池的电解质添加剂。,ACS Applied Materials & Interfaces

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二氟磷酸钾作为钾离子电池的电解质添加剂。
ACS Applied Materials & Interfaces ( IF 8.3 ) Pub Date : 2020-07-21 , DOI: 10.1021/acsami.0c09562
Huan Yang ₁ , Chih-Yao Chen ₂ , Jinkwang Hwang ₁ , Keigo Kubota ₂ , Kazuhiko Matsumoto _{1,

2,

3} , Rika Hagiwara _{1,

2,

3}

Affiliation

石墨负极的有限的可循环性和较差的库仑效率一直是其在钾离子电池（PIB）中实际应用的主要障碍。本文首次通过促进稳定的K ^{+ +}的形成，证明了二氟磷酸钾（KDFP）电解质添加剂是解决这些瓶颈的可行方案。石墨上的导电固体-电解质中间相（SEI）。向电解液中添加0.2 wt％的KDFP可显着改善（去）钾化动力学，容量保持率（使用KDFP进行400次循环后为76.8％，而不使用KDFP进行100次循环后为27.4％）和平均库仑效率（〜99.9％）在400个循环中）。而且，与不含KDFP的电解质相比，含KDFP的电解质还能够以更高的效率和更低的界面电阻实现K / K对称电池的持久循环。X射线衍射和拉曼光谱分析已证实可纯相形成的阶段1钾-石墨插层化合物（KC ₈）借助KDFP。基于X射线光电子能谱对石墨和K金属电极上的SEI层的分析，讨论了通过添加KDFP增强的电化学性能。

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Potassium Difluorophosphate as an Electrolyte Additive for Potassium-Ion Batteries.

The limited cyclability and inferior Coulombic efficiency of graphite negative electrodes have been major impediments to their practical utilization in potassium-ion batteries (PIBs). Herein, for the first time, potassium difluorophosphate (KDFP) electrolyte additive is demonstrated as a viable solution to these bottlenecks by facilitating the formation of a stable and K⁺-conducting solid–electrolyte interphase (SEI) on graphite. The addition of 0.2 wt % KDFP to the electrolyte results in significant improvements in the (de)potassiation kinetics, capacity retention (76.8% after 400 cycles with KDFP vs 27.4% after 100 cycles without KDFP), and average Coulombic efficiency (∼99.9% during 400 cycles) of the graphite electrode. Moreover, the KDFP-containing electrolyte also enables durable cycling of the K/K symmetric cell at higher efficiencies and lower interfacial resistance as opposed to the electrolyte without KDFP. X-ray diffraction and Raman spectroscopy analyses have confirmed the reversible formation of a phase-pure stage-1 potassium–graphite intercalation compound (KC₈) with the aid of KDFP. The enhanced electrochemical performance by the KDFP addition is discussed based on the analysis of the SEI layer on graphite and K metal electrodes by X-ray photoelectron spectroscopy.

更新日期：2020-08-12

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