High Performance Lithium Secondary Batteries Based on Novel Ni₃Co₆S₈@C Core—Shell Nanoparticle

As one new type of cathode materials, transition metal sulfides with the advantages of high energy density and high electronic conductivity have attracted a lot of attentions to fulfill the demands of high power and energy battery applications in hybrid electric vehicles (HEVs) and electric vehicles (EVs). Herein, we report the synthesis of one novel ternary sulfide of Ni₃Co₆S₈@C urchin-like core—shell nanoparticles as cathode materials for lithium secondary batteries with sodium alginate as the binder and lithium foil as the anode. The novel Ni₃Co₆S₈@C nanoparticles show high discharge specific capacity, excellent cycling stability and much better rate capability. Based on the overall mass of the Ni₃Co₆S₈@C nanoparticles, it could achieve an initial energy density of 957 Wh kg^-1, and a respective energy density of 606 and 508 Wh kg^-1 after 100 and 200 cycles. The outstanding performance of the Ni₃Co₆S₈@C electrode could be attributed to the carbon coating and sodium alginate binder, because these strategies could significantly inhibit the volume change, aggregation and pulverization of Ni₃Co₆S₈@C nanoparticles.