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Potassium Difluorophosphate as an Electrolyte Additive for Potassium Ion Batteries

Yang, Huan and Chen, Chih-Yao and Hwang, Jinkwang and Kubota, Keigo and Matsumoto, Kazuhiko and Hagiwara, Rika (2020) Potassium Difluorophosphate as an Electrolyte Additive for Potassium Ion Batteries. ACS Applied Materials & Interfaces, 12 (32). pp. 36168-36176. ISSN 1944-8244.

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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.

Item Type:Article
Related URLs:
URLURL TypeDescription
Yang, Huan0000-0002-8757-5733
Chen, Chih-Yao0000-0002-8799-4647
Hwang, Jinkwang0000-0003-4800-3158
Kubota, Keigo0000-0002-0536-129X
Matsumoto, Kazuhiko0000-0002-0770-9210
Hagiwara, Rika0000-0002-7234-3980
Additional Information:© 2020 American Chemical Society. Received: May 25, 2020; Accepted: July 21, 2020; Published: July 21, 2020. This study was partly supported by the Japanese Ministry of Education, Culture, Sports, Science and Technology (MEXT) program “Elements Strategy Initiative to Form Core Research Center” (JPMXP0112101003) and Japan Society for the Promotion of Science (JSPS, KAKENHI Grant Number 19H04695). One of the authors, H.Y., thanks to the China Scholarship Council (CSC) for the financial support. The authors declare no competing financial interest.
Funding AgencyGrant Number
Ministry of Education, Culture, Sports, Science and Technology (MEXT)JPMXP0112101003
Japan Society for the Promotion of Science (JSPS)19H04695
Subject Keywords:Potassium difluorophosphate (KDFP), Electrolyte additive, Potassium-ion batteries, Graphite, Graphite intercalation compounds (GICs)
Issue or Number:32
Record Number:CaltechAUTHORS:20200722-103823636
Persistent URL:
Official Citation:Potassium Difluorophosphate as an Electrolyte Additive for Potassium-Ion Batteries. Huan Yang, Chih-Yao Chen, Jinkwang Hwang, Keigo Kubota, Kazuhiko Matsumoto, and Rika Hagiwara. ACS Applied Materials & Interfaces 2020 12 (32), 36168-36176; DOI: 10.1021/acsami.0c09562
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:104506
Deposited By: Tony Diaz
Deposited On:22 Jul 2020 18:43
Last Modified:14 Aug 2020 16:37

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