A dithiol-based new electrolyte additive for improving electrochemical performance of NCM811 lithium ion batteries
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ORIGINAL PAPER
A dithiol-based new electrolyte additive for improving electrochemical performance of NCM811 lithium ion batteries Shuang Wan 1 & Shimou Chen 2 Received: 11 August 2020 / Revised: 29 August 2020 / Accepted: 1 September 2020 # Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract LiNi0.8Co0.1Mn0.1O2 (NCM811) has received widespread attention due to its high discharge specific capacity. However, poor cycling performance and rate capacity limit its large-scale commercial applications. Here, we develop 4,5-Dicyano-1,3-dithiol-2one (DDO) as a new type additive to enhance the cycling performance and rate capacity of NCM811/Li+ half cell. Electrochemical tests show that the discharge capacity retention rate of cell is 75.59% after 200 cycles with 0.1 wt% DDOcontaining electrolyte, while the cell with blank electrolyte is only 15.11%. The initial coulomb efficiency and rate capacity with 0.1 wt% DDO are higher than the blank one. Through scanning electron microscope (SEM) analysis, the particle of NCM811 is smooth and integral after 50th cycled, while the particle ruptures in blank electrolyte. The outstanding electrochemical performance of NCM811 is attributed to the stable and uniform cathode electrolyte interphase (CEI) film formed by DDO. Moreover, X-ray photoelectron spectroscopy (XPS) reveals that DDO prevents the decomposition of carbonate solvents and nickel element dissolution of NCM811. Other tests also confirm that the robust CEI layer can reduce the polarization and internal resistance of the cell during cycles. Keywords Lithium-ion battery . NCM811 . 4,5-Dicyano-1,3-dithiol-2-one . Cathode-electrolyte interface
Introduction With the increasing requirements of new energy policy and market demand for high-performance batteries, how to increase the energy density and safety of the batteries has attracted more and more attentions. Nickel-rich cathode materials are the critical material of high energy density lithium battery in the next-generation energy-storage devices [1]. Among the nickel-rich cathode materials, NCM811 (LiNi0.8Co0.1Mn0.1O2) is extensively studied by researchers due to its high charge/discharge capacity, high operating voltage, long cycle life, and low cost [2, 3]. However, some drawbacks limit its widespread development in LIBs compared
* Shimou Chen [email protected] 1
Zhengzhou Key Laboratory of Energy Storage Science and Technology, Zhengzhou Institute of Emerging Industrial Technology, Zhengzhou 45000, China
2
Key Laboratory of Green Process and Engineering, Institute of Process Engineering (IPE), Chinese Academy of Sciences (CAS), Beijing 100190, People’s Republic of China
with lower Ni contents materials, (1) Unstable oxygen element: Oxygen element in layered structure of NCM811 is easy to come out during cycling or under high temperature; the oxygen defects generate lattice defects and cause safety hazards, and this problem can usually be solved by elements doping [4]; (2) Surface alkali content: The residual lithium on the surface of NCM811 will re
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