Dual Confinement of CoSe2 Nanorods with Polyphosphazene-Derived Heteroatom-Doped Carbon and Reduced Graphene Oxide for Potassium-Ion Batteries

Zhongshu Zhao; Chenqi Gao; Jinchen Fan; Penghui Shi; Qunjie Xu; Yulin Min

doi:10.1021/acsomega.1c02649

Dual Confinement of CoSe₂ Nanorods with Polyphosphazene-Derived Heteroatom-Doped Carbon and Reduced Graphene Oxide for Potassium-Ion Batteries

ACS Omega. 2021 Jun 23;6(26):17113-17125. doi: 10.1021/acsomega.1c02649. eCollection 2021 Jul 6.

Authors

Zhongshu Zhao¹, Chenqi Gao¹, Jinchen Fan^{1

2}, Penghui Shi^{1

2}, Qunjie Xu^{1

2}, Yulin Min^{1

2}

Affiliations

¹ Shanghai Key Laboratory of Materials Protection and Advanced Materials in Electric Power, College of Environmental and Chemical Engineering, Shanghai University of Electric Power, Shanghai 200090, China.
² Shanghai Institute of Pollution Control and Ecological Security, Shanghai 200092, China.

Abstract

High-capacity and highly stable anode materials are some of the keys to the realization of the application of potassium-ion batteries (PIBs). Cobalt diselenide (CoSe₂) has been regarded as a high-potential anode material for PIBs. However, solving the problems of sluggish kinetics and large volumetric expansion during intercalation/deintercalation of K⁺ ions is always very challenging in terms of cobalt diselenide-based anode materials. Herein, reduced graphene oxide-encapsulated polyphosphazene-derived S, P, and N codoped carbon (SPNC)-coated CoSe₂ nanorods (CoSe₂⊂SPNC⊂rGO) were designed as PIB anode materials. CoSe₂⊂SPNC⊂rGO delivers an excellent reversible capacity of 287.2 mAh g^-1 at 100 mA g^-1. Benefiting from the coating of heteroatom-doped carbon and encapsulation of rGO, the CoSe₂⊂SPNC⊂rGO anodes exhibit a remarkable rate capability (100-1500 mA g^-1 current density) and high stability (208.8 mAh g^-1 after 500 cycles at 500 mA g^-1). The results demonstrate that S, P, and N codoping in carbon layers provides active sites for K⁺ ion storage and increases the electrical conductivity. More importantly, the dual confinement of CoSe₂ nanorods with carbon layers and rGO significantly reduced the volume expansion and kept the electrode structural integrity with repeating intercalation/deintercalation of K⁺ ions.