Highly Improved Cycling Stability of Anion De‐/Intercalation in the Graphite Cathode for Dual‐Ion Batteries

• Published in: Advanced materials (Weinheim) Vol. 31; no. 4; pp. e1804766 - n/a
• Main Authors: Li, Wen‐Hao, Ning, Qiu‐Li, Xi, Xiao‐Tong, Hou, Bao‐Hua, Guo, Jin‐Zhi, Yang, Yang, Chen, Bin, Wu, Xing‐Long
• Format: Journal Article
• Language: English
• Published: Germany Wiley Subscription Services, Inc 01.01.2019
• Subjects: Anions; Batteries; Cathodes; Cathodic protection; Current carriers; cycling stability; Decomposition; dual‐ion batteries; Electrodes; Electrolytes; Energy storage; Flux density; Graphite; interface modification; Materials science; Solid electrolytes; Stability; interface modification; dual-ion batteries; graphite; cathodes; cycling stability
• ISSN: 0935-9648; 1521-4095; 1521-4095
• DOI: 10.1002/adma.201804766

Conventional ion batteries utilizing metallic ions as the single charge carriers are limited by the insufficient abundance of metal resources. Although supercapacitors apply both cations and anions to store energy through absorption and/or Faradic reactions occurring at the interfaces of the electrode/electrolyte, the inherent low energy density hinders its application. The graphite‐cathode‐based dual‐ion battery possesses a higher energy density due to its high working potential of nearly 5 V. However, such a battery configuration suffers from severe electrolyte decomposition and exfoliation of the graphite cathode, rendering an inferior cycle life. Herein, a new surface‐modification strategy is developed to protect the graphite cathode from the anion salvation effect and the deposition derived from electrolyte decomposition by generating an artificial solid electrolyte interphase (SEI). Such SEI‐modified graphite exhibits superior cycling stability with 96% capacity retention after 500 cycles under 200 mA g−1 at the upper cutoff voltage of 5.0 V, which is much improved compared with the pristine graphite electrode. Through several ex situ studies, it is revealed that the artificial SEI greatly stabilizes the interfaces of the electrode/electrolyte after reconstruction and gradual establishment of the optimal anion‐transport path. The findings shed light on a new avenue toward promoting the performance of the dual‐ion battery (DIB) and hence to make it practical finally. An artificial layer of a solid electrolyte interphase is fabricated on a graphite cathode for a dual‐ion battery (DIB). Such surface modification can alleviate the electrolyte decomposition at the high working voltage of the anion de‐/intercalation processes and the solvation effect of anions, much improving the cycling stability of the Li//graphite DIB.