Synthesis and characterization of LiFe0.5Mn0.3Co0.2PO4/C composite material for high-voltage Li-ion battery application

• Published in: Journal of alloys and compounds 2018-06, Vol.750, p.945-958
• Main Authors: Yang, Chun-Chen, Hsu, Ya-Ting, Karuppiah, Chelladurai, Shih, Jeng-Ywan, Wu, Yi-Shiuan, Wu, Zong-Han, Lue, Shingjiang Jessie
• Format: Article
• Language: English
• Subjects: Carbon coated cathode; Flower-like Co3O4; High voltage Li-ion battery; LiFe0.5Mn0.3Co0.2PO4/C; Solid-state method; Trimethyl boroxane
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2018.04.098

A LiFe0.5Mn0.3Co0.2PO4/C composite cathode material was prepared using a solid-state ball-milling method. The flower-like Co3O4 precursor was prepared by hydrothermal method and used to improve the electrochemical properties of composite material. The galvanostatic charge–discharge profile is performed in the potential range of 2–5 V by using different electrolyte compositions with/without 1 wt% trimethyl boroxane (TMB) additive at various C rates. The highest discharge capacities of the composite material were 150.42 mAh g−1 at 0.1C and 120 mAh g−1 at 1C in LiPF6+1 wt%TMB in EC:EMC (1:2, v/v). In addition, the excellent cycle-life was observed at 0.1C and 1C rate for 30 and 100 cycles with the charge retention of 97.7% and 73%, respectively. These appreciable results were obtained due to the carbon coating layer and highly active composite material. The thickness of cathode electrolyte interphase layer on composite electrode is ca. 3 nm which was measured by secondary ion mass spectroscopy. And also, we found that the B element on interphase layer that acts as F-scavenger to reduce the amount of LiF formation over cathode interphase layer. As a result, it can markedly reduce the charge transfer resistance and improve the electrochemical performance for long-term cycling. [Display omitted] •The work reports the preparation of LiFe0.5Mn0.3Co0.2PO4/C by a solid-state method.•Flower-like nano-sized Co3O4 is prepared by a hydrothermal process.•The capacity of LFMCP/C with 1%TMB shows 150 mAh g−1 at 0.1C and 120 mAh g−1 at 1C.•XPS and SIMS were used to study the properties of CEI with and without 1%TMB.•We propose a dual layer structure CEI model for LFMCP.