Insights into the Electrochemical Reaction Mechanism of a Novel Cathode Material CuNi2(PO4)2/C for Li-Ion Batteries

Wengao Zhao; Guiming Zhong; Jian Zheng; Jianming Zheng; Junhua Song; Zhengliang Gong; Zheng Chen; Guorui Zheng; Zheng Jiang; Yong Yang

doi:10.1021/acsami.7b15086

Insights into the Electrochemical Reaction Mechanism of a Novel Cathode Material CuNi₂(PO₄)₂/C for Li-Ion Batteries

ACS Appl Mater Interfaces. 2018 Jan 31;10(4):3522-3529. doi: 10.1021/acsami.7b15086. Epub 2018 Jan 16.

Authors

Wengao Zhao, Guiming Zhong¹, Jian Zheng², Jianming Zheng³, Junhua Song³, Zhengliang Gong, Zheng Chen, Guorui Zheng, Zheng Jiang⁴, Yong Yang

Affiliations

¹ Xiamen Institute of Rare Earth Materials, Haixi Institutes, Chinese Academy of Sciences , Xiamen 361021, China.
² Institute for Integrated Catalysis, and Fundamental and Computational Science Directorate, Pacific Northwest National Laboratory , Richland, Washington 99352, United States.
³ Energy and Environmental Directorate, Pacific Northwest National Laboratory , 902 Battelle Boulevard, Richland, Washington 99354, United States.
⁴ Shanghai Institute of Space Power-Sources, No. 2965 Dongchuan Road, Shanghai 200245, China.

PMID: 29286631
DOI: 10.1021/acsami.7b15086

Abstract

In this work, we first report the composite of CuNi₂(PO₄)₂/C (CNP/C) can be employed as the high-capacity conversion-type cathode material for rechargeable Li-ion batteries (LIBs), delivering a reversible capacity as high as 306 mA h g^-1 at a current density of 20 mA g^-1. Furthermore, CNP/C also presents good rate performance and reasonable cycling stability based on a nontraditional conversion reaction mode. X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM) characterizations show that CNP is reduced to form Cu/Ni and Li₃PO₄ during the discharging process, which is reversed in the following charging process, demonstrating that a reversible conversion reaction mechanism occurs. X-ray absorption spectroscopy (XAS) discloses that Ni²⁺/Ni⁰ exhibits a better reversibility compared to Cu²⁺/Cu during the conversion reaction process, while Cu⁰ is more difficult to be reoxidized during the recharge process, leading to capacity loss as a consequence. The fundamental understanding obtained in this work provides some important clues to explore the high-capacity conversion-type cathode materials for rechargeable LIBs.

Keywords: CuNi2(PO4)2/C; XAS; conversion reaction; high capacity; reversibility.