4.8 Article

Nature of the Cathode-Electrolyte Interface in Highly Concentrated Electrolytes Used in Graphite Dual-Ion Batteries

期刊

ACS APPLIED MATERIALS & INTERFACES
卷 13, 期 3, 页码 3867-3880

出版社

AMER CHEMICAL SOC
DOI: 10.1021/acsami.0c18586

关键词

graphite; anion intercalation; concentrated electrolyte; cathode-electrolyte interface; photoelectron spectroscopy; battery

资金

  1. Swedish Energy Agency [2015-009549, 2016-006026]
  2. Vetenskapsradegreesdet [D-2017-05466]
  3. Vinnova [2019-00064]
  4. Uppsala University
  5. STandUp for Energy consortium

向作者/读者索取更多资源

Dual-ion batteries (DIBs) operating at voltages beyond 4.7 V exhibit different performances based on the electrolyte used, with higher Coulombic efficiency and specific capacity achieved in HCEs with LiFSI and LiTFSI salts compared to those with LiPF6. XPS analysis reveals that LiFSI and LiTFSI electrolytes result in thinner surface layers on intercalated graphite electrodes compared to LiPF6, indicating a difference in interface formation and decomposition product buildup.
Dual-ion batteries (DIBs) generally operate beyond 4.7 V vs Li+/Li-0 and rely on the intercalation of both cations and anions in graphite electrodes. Major challenges facing the development of DIBs are linked to electrolyte decomposition at the cathode-electrolyte interface (CEI), graphite exfoliation, and corrosion of Al current collectors. In this work, X-ray photoelectron spectroscopy (XPS) is employed to gain a broad understanding of the nature and dynamics of the CEI built on anion-intercalated graphite cycled both in highly concentrated electrolytes (HCEs) of common lithium salts (LiPF6, LiFSI, and LiTFSI) in carbonate solvents and in a typical ionic liquid. Though AI metal current collectors were adequately stable in all HCEs, the Coulombic efficiency was substantially higher for HCEs based on LiFSI and LiTFSI salts. Specific capacities ranging from 80 to 100 mAh g(-1) were achieved with a Coulombic efficiency above 90% over extended cycling, but cells with LiPF6-based electrolytes were characterized by <70% Coulombic efficiency and specific capacities of merely ca. 60 mAh g(-1). The poor performance in LiPF6-containing electrolytes is indicative of the continual buildup of decomposition products at the interface due to oxidation, forming a thick interfacial layer rich in LixPFy, POxFy, LixPOyFz, and organic carbonates as evidenced by XPS. In contrast, insights from XPS analyses suggested that anion intercalation and deintercalation processes in the range from 3 to 5.1 V give rise to scant or extremely thin surface layers on graphite electrodes cycled in LiFSI- and LiTFSI-containing HCEs, even allowing for probing anions intercalated in the near-surface bulk. In addition, ex situ Raman, SEM and TEM characterizations revealed the presence of a thick coating on graphite particles cycled in LiPF6-based electrolytes regardless of salt concentration, while hardly any surface film was observed in the case of concentrated LiFSI and LiTFSI electrolytes.

作者

我是这篇论文的作者
点击您的名字以认领此论文并将其添加到您的个人资料中。

评论

主要评分

4.8
评分不足

次要评分

新颖性
-
重要性
-
科学严谨性
-
评价这篇论文

推荐

暂无数据
暂无数据