An Ostwald ripening-based route is proposed to prepare Ni-rich layered cathodes with Co-rich surface for li- thium-ion batteries （LIBs）. Commercially available Nio.aCo0.1 Mn0.8（OH）2 and spray pyrolysis derived por...An Ostwald ripening-based route is proposed to prepare Ni-rich layered cathodes with Co-rich surface for li- thium-ion batteries （LIBs）. Commercially available Nio.aCo0.1 Mn0.8（OH）2 and spray pyrolysis derived porous Co304 are used as mixed precursors. During the lithiation reaction process under high-temperature, the porous Co304 microspheres scatter primary particles and spontaneously redeposit on the surface of Ni-rich spheres according to Ostwald ripening mechanism, forming the Ni-rich materials with Co-rich outer layers. When evaluated as cathode for LIBs, the resultant material shows ability to inhibit the cation disorder, relieves the phase transition from H2 to H3 and diminishes side re- actions between the electrolyte and Ni-rich cathode material. As a result, the obtained material with Co-rich outer layers exhibits much more improved cycle and rate performance than the material without Co-rich outer layers. Particularly, NCM-Co-1 （molar ratio of Nio.sCo0.1Mn0.1（OH）2/Co3Oa is 60：1） delivers a reversible capacity of 159.2 mA h g-1 with 90.5% capacity retention after 200 cycles at 1 C. This strategy pro- rides a general and efficient way to produce gradient sub- stances and to address the surface problems of Ni-rich cathode materials.展开更多
基金the financial support of the National Basic Research Program of China (2014CB643406)the National Natural Science Foundation of China (51674296, 51574287, 51704332)+1 种基金the National Postdoctoral Program for Innovative Talents (BX201700290)the Fundamental Research Funds for the Central Universities of Central South University (2017zzts125)
文摘An Ostwald ripening-based route is proposed to prepare Ni-rich layered cathodes with Co-rich surface for li- thium-ion batteries （LIBs）. Commercially available Nio.aCo0.1 Mn0.8（OH）2 and spray pyrolysis derived porous Co304 are used as mixed precursors. During the lithiation reaction process under high-temperature, the porous Co304 microspheres scatter primary particles and spontaneously redeposit on the surface of Ni-rich spheres according to Ostwald ripening mechanism, forming the Ni-rich materials with Co-rich outer layers. When evaluated as cathode for LIBs, the resultant material shows ability to inhibit the cation disorder, relieves the phase transition from H2 to H3 and diminishes side re- actions between the electrolyte and Ni-rich cathode material. As a result, the obtained material with Co-rich outer layers exhibits much more improved cycle and rate performance than the material without Co-rich outer layers. Particularly, NCM-Co-1 （molar ratio of Nio.sCo0.1Mn0.1（OH）2/Co3Oa is 60：1） delivers a reversible capacity of 159.2 mA h g-1 with 90.5% capacity retention after 200 cycles at 1 C. This strategy pro- rides a general and efficient way to produce gradient sub- stances and to address the surface problems of Ni-rich cathode materials.
