Preparation and Electrochemical Properties of Poly(3-hexylthiophene)-coated Lithium-rich Layered Cathode Material Li1.18Ni0.15Co0.15Mn0.52O2†

doi:10.7503/cjcu20180683

Abstract

Abstract:

Lithium-rich layered cathode material Li_1.18Ni_0.15Co_0.15Mn_0.52O₂ was synthesized by sol-gel method and then coated with poly(3-hexylthiophene). Varies spectroscopic and electrochemical techniques were used to analyze the morphology and electrochemical properties of the materials. The results showed that a homogeneous coating layer with a thickness of ca. 1.5 nm was formed on the surface of the material. The electrode polarization and impedance of the material were obviously reduced by surface coating. After 100 cycles at 0.2C, the specific capacity of the original material decreased to 170 mA·h/g, while that of the 0.3% poly(3-hexylthiophene) coated material still remained at 205 mA·h/g. The corresponding capacity retention increased from 68% to 82%. Moreover, the discharge capacity at 10C rate increased from 72 mA·h/g to 116 mA·h/g.

Key words: Lithium-ion battery, Cathode material, Surface coating, Li-rich material, Poly(3-hexylthiophene)

CLC Number:

O646

TrendMD:

CHEN Hong,DU Yonghui,ZHANG Xin,LIU Wenyan,ZHOU Xiaoming. Preparation and Electrochemical Properties of Poly(3-hexylthiophene)-coated Lithium-rich Layered Cathode Material Li_1.18Ni_0.15Co_0.15Mn_0.52 $O 2 †$ [J]. Chem. J. Chinese Universities, 2019, 40(4): 777.

Figures/Tables 11

Fig.1 XRD patterns of the original and P3HT coated Li-rich materialsa. Original; b. 0.1%P3HT; c. 0.3%P3HT; d. 0.5%P3HT.

Fig.2 SEM images of the original(A, B) and 0.3%P3HT coated(C, D) Li-rich materials

Fig.3 High resolution TEM images of the original(A) and 0.3%P3HT coated(B) Li-rich material

Fig.4 FTIR spectra of the original(a) and 0.5% P3HT coated(b) Li-rich materials

Fig.5 Cyclic performance of the original and P3HT coated Li-rich materials at 0.2C rate(40 mA/g)

Fig.6 Charge/discharge curves of the original(A) and 0.3%P3HT coated(B) material at 0.2C rate

Fig.7 Rate performance of the original and P3HT coated Li-rich materials

Fig.8 Charge/discharge curves of the original(A) and P3HT coated(B) Li-rich materials at different cycle rates

Fig.9 CV curves of original and P3HT coated Li-rich materials in initial five cycles (A) Original; (B) 0.1%P3HT; (C) 0.3%P3HT; (D) 0.5%P3HT.

Fig.10 Comparison of the fifth CV curves

Fig.11 Nyquist curves of the original(a) and 0.3%P3HT coated(b) Li-rich materials(A) and the equivalent circuit(B)R0 is the internal resistance, RSEI/CSEI are the SEI resistance/capacitance, respectively; Rct/Cdl are the charge transfer resistance/capacitance, respectively; W0 is the Warburg resistance. First charge to 4.5 V.

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