Synthesis of LiNi0.8Co0.15Al0.05O2 with 5-sulfosalicylic acid as a chelating agent and its electrochemical properties

A spherical LiNi0.8Co0.15Al0.05O2 (LNCA) cathode material with excellent electrochemical performance for lithium-ion batteries is successfully synthesized with the precursor of Ni0.8Co0.15Al0.05(OH)(2) (NCA) prepared by a continuous co-precipitation method. A more environmentally friendly chelating agent, 5-sulfosalicylic acid (SSA, H3L), stable as well as non-toxic, is adopted in our synthesis process for the first time instead of traditional NH3 center dot H2O. The thermodynamics of the precipitation from the Ni(II)-Co(II)-Al(III)-SSA-H2O system at 298 K is systematically investigated through thermodynamics model analysis. The results demonstrate that the stoichiometric spherical Ni0.8Co0.15Al0.05(OH)(2) precursor can be obtained at pH = 11-13, with the SSA concentration from 0.05 mol L-1 to 0.5 mol L-1. LiNi0.8Co0.15Al0.05O2 prepared from the precursor has an initial discharge specific capacity of 203.1 mA h g(-1) at 0.1C and a capacity retention of 93.3% after 200 cycles when cycled at 1C between 3.0 and 4.3 V, as well as excellent rate capability. The electrochemical performances are superior to those prepared by using ammonia as the chelating agent. It is expected that the LiNi0.8Co0.15Al0.05O2 cathode material can be synthesized by a more environmentally friendly method.