Binary　metal　sulfides　have　been　considered　as　promising　electrode　materials　for　supercapacitors　with　excellent　performance.　Herein,　we　demonstrate　a　simple　two-step　hydrothermal　method　to　grow　the　interconnected　Co9S8/NiCo2S4　nanosheet　arrays　(denoted　as　Ni-Co　sulfide　NSAs)　on　nickel　foam　with　robust　adhesion　for　high　performance　supercapacitors.　Remarkably,　the　as-synthesized　Ni-Co　sulfide　binder-free　electrode　exhibits　an　ultrahigh　areal　capacitance　of　7.4　F　cm(-2)　for　supercapacitors,　which　is　about　five　times　higher　than　1.5　F　cm(-2)　of　the　Ni-Co　oxide　electrode　at　the　current　density　of　5　mA　cm(-2).　The　Ni-Co　sulfide　binder-free　electrode　also　exhibits　a　good　cycling　stability,　which　still　displays　a　high　capacitance　retention　of　90.7%　after　2000　cycles　even　at　a　high　current　density　of　40　mA　cm(-2).　The　good　electrochemical　performance　could　be　ascribed　to　the　high　electrical　conductivity　and　porous　nanosheet　structure　of　the　Ni-Co　sulfide　nanosheets,　as　well　as　the　robust　adhesion　with　the　current　collector.　These　electrochemical　results　suggest　that　such　Ni-Co　sulfide　NSA　binder-free　electrode　might　hold　some　potential　for　electrochemical　energy　applications.　(C)　2017　Elsevier　B.V.　All　rights　reserved.