Binder-Free Metal Sulfide Composite Nanosheet Array Electrodes for Li-Ion Batteries

In this work, metal sulfide composite nanosheet arrays are directly grown on Ni foam substrates using chemical bath deposition to construct binder-free electrodes for Li-ion batteries. Structural characterizations indicate that the nanosheets are composed of nickel cobalt sulfide and nickel sulfide nanocrystals with sizes of 2-5 nm embedded in an amorphous matrix. Superior reversible capacity, cycling stability, and rate performance are acquired from the binder-free metal sulfide composite nanosheet electrode compared to the binder-free granular metal sulfide composite film electrode, which is attributed to the unique morphology and structure of the nanosheet array. At a current density of 200 mAg^-1, 10% capacity loss is acquired from the binder-free metal sulfide composite nanosheet electrode after 100 cycles. The nanosheet electrode also exhibits a promising rate performance that the reversible capacities of 1860, 1610, 1350, 1170, and 1050 mAhg^-1 are measured at current densities of 200, 500, 1000, 2000, and 3000 mAg^-1, respectively.