ZnO/CuO Microspheres Modified with Nitrogen-doped Carbon-coating for Lithium-ion Batteries

doi:10.15541/jim20250409

Abstract

Abstract:

ZnO, a transition metal oxide, possesses a high theoretical capacity of 978 mAh·g⁻¹ as an anode for lithium batteries. However, its cycling stability and capacity retention still need to be improved. Therefore, ZnO/CuO microspheres modified with nitrogen-doped carbon-coating (ZnO/CuO/N-C) were synthesized using Cu-ZnSe microspheres as a template and dopamine hydrochloride as raw material. This synthesis strategy simultaneously achieves the conversion of active materials, construction of internal pore structure, and coating of external conductive carbon layer. The electrochemical properties of ZnO/CuO microspheres anode are greatly improved after the treatment of nitrogen-doped carbon-coating. The pyridine nitrogen, pyrrole nitrogen, and graphite nitrogen are formed after nitrogen doping into ZnO/CuO microspheres, significantly increasing surface active sites and promoting ion and electron transfer. A large number of defects are generated in the inner composites after carbon coating, advantageous for providing more active sites for surface redox reactions. The ZnO/CuO/N-C microspheres, as anode material of Li-ion batteries, exhibit excellent electrochemical properties. They still display a high specific capacity of 1010.4 mAh·g⁻¹ at 0.1 A·g⁻¹after 200 cycles. The specific capacity of ZnO/CuO/N-C microspheres anode could reach 447.1 mAh·g⁻¹ at a high current density of 1 A·g⁻¹after 1000 cycles. The excellent rate performance is exhibited in the process of Li⁺ ions insertion, ascribed to a high contribution of pseudocapacitance. The improved electrochemical properties of ZnO/CuO/N-C microspheres can be ascribed to the following factors. The structural integrity of composites could be maintained by buffering volume expansion after carbon-coating. The electrolyte infiltration and ion transport can be promoted due to the existence of internal pores. A high capacity is caused through the conversion and alloying reactions between ZnO and CuO.

Key words: ZnO/CuO, nitrogen-doped carbon-coating, microsphere, lithium-ion battery anode

CLC Number:

TB332

ZHANG Gaoju, REN Haibo, LI Wenzheng, WANG Gang. ZnO/CuO Microspheres Modified with Nitrogen-doped Carbon-coating for Lithium-ion Batteries[J]. Journal of Inorganic Materials, 2026, 41(9): 1211-1219.

Figures/Tables 12

Fig. 1 XRD patterns of (a) Cu-ZnSe and (b) ZnO/CuO/N-C

Fig. 2 XPS spectra of ZnO/CuO/N-C (a) Full spectrum; (b) Zn2p; (c) O1s; (d) C1s; (e) N1s; (f) Cu2p

Fig. 3 SEM images of (a-c) Cu-ZnSe, (d-f) ZnO/CuO/N-C and (g-i) ZnO/CuO; (j, k) TEM and (l) HRTEM images of ZnO/CuO/N-C

Fig. 4 Raman spectrum of ZnO/CuO/N-C

Fig. 5 (a) Initial four CV curves of ZnO/CuO/N-C anode at a scan rate of 1 mV·s−1; (b) Charge-discharge curves for the 1st, 2nd, 3rd, 10th, 20th, 50th, 100th and 200th cycle at a current density of 0.1 A·g−1 of ZnO/CuO/N-C anode; (c) Cycling performance of ZnO/CuO/N-C, ZnO/CuO and Cu-ZnSe anodes at 0.1 A·g−1; (d) Rate performance of ZnO/CuO/N-C, Cu-ZnSe and ZnO/CuO anodes Colorful figures are available on website

Fig. 6 (a) CV curves of ZnO/CuO/N-C anode at different scan rates; (b) lgi-lgv fitting lines; (c) Capacitance control proportion histogram at different sweep speeds; (d) Fitting areas of capacitance control in CV curves at a scan rate of 1 mV·s−1 Colorful figures are available on website

Fig.7 (a) Nyquist plots of ZnO/CuO/N-C, ZnO/CuO and Cu-ZnSe batteries; (b)Warburg impedance linear fitting diagram of ZnO/CuO/N-C, ZnO/CuO and Cu-ZnSe anodes

Fig. S1 Schematic diagram of ZnO/CuO/N-C microsphere material synthesis

Fig. S2 Nitrogen adsorption-disadsorption isotherms of (a) Cu-ZnSe, (b) ZnO/CuO and (c) ZnO/CuO/N-C with insets showing the corresponding pore size distributions

Fig. S3 (a) Performance of ZnO/CuO/N-C, ZnO/CuO and Cu-ZnSe for 500 cycles at 1 A·g−1; (b) Performance of ZnO/CuO/N-C for 1000 cycles at 1 A·g−1

Table S1 Electrochemical properties of ZnO/CuO/N-C and reported ZnO-based anodes

Material	Current density/(A·g⁻¹)	Cycle number	Specific capacity/(mAh·g⁻¹)	Ref.
ZnO/CuO/N-C	0.1	200	1010.4	This work
ZnO/CuO/N-C	1	1000	447.1	This work
ZnO/MnO	1	1000	315.0	[S1]
ZnO@C	0.1	100	500.0	[S2]
ZnO/CuO/GNS	0.3	50	186.1	[S3]
CuO-ZnO@Al₂O₃	0.1	50	715.0	[S4]
CS-ZnO-60@NC	0.2	500	940.9	[S5]

Fig. S4 SEM images of (a-c) Cu-ZnSe, (d-f) ZnO/CuO and (g-i) ZnO/CuO/N-C after 200 cycles

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