Dual-Carbon Engineering of Nanosized (Ni0.28Co0.72)1-x S for Li+ Storage with Enhanced Rate Capability and Stability

摘要

Thepoor conductivity and large volume swelling of transition-metalsulfides are still big challenges to overcome for high-performanceenergy storage. Herein, the flexibility of MOF precursors offers remarkableversatility in tailoring the chemical composition of NiCo sulfideswith a highly desirable porous structure, and then dual-carbon-confined(Ni0.28Co0.72)(1-x) S nanoparticles are designed, in which an inner sulfur-dopedporous carbon (SC) matrix (derived from the organic ligands of metal-organicframeworks (MOFs)) and an outer wrapped S-doped reduced graphene oxide(SG)-co-engineered (Ni0.28Co0.72)(1-x) S are constructed ((Ni0.28Co0.72)(1-x) S/SC/SG)) to enhance the ratecapability and stability of Li+ storage. For the dual carbons,the inner SC can elastically realize the anti-aggregation of nanosized(Ni0.28Co0.72)(1-x) S and improve their conductivity, while the outer SG couldfurther promote the reaction kinetics, stabilize the structure, andensure the structural integrity. As expected, the optimized (Ni0.28Co0.72)(1-x) S/SC/0.7SG exhibits an outstanding rate capability of 640.1 mAh g(-1) at 5.0 A g(-1) and ultrahigh cyclingstability of 134.7% at 1 A g(-1) after 1000 cycles.The assembled lithium-ion capacitor (LIC) also shows a high energydensity of 125.8 Wh kg(-1) at the power density of200 W kg(-1), as well as excellent stability (98.8%after 6000 cycles). This work highlights the significance of dual-carbonengineering in enhancing the energy storage performance of activematerials, and the fabricated nanosized (Ni0.28Co0.72)(1-x) S by dual-carbon engineeringcan be applied in high-performance electrochemical energy storageand beyond.

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