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

Abstract

A spherical LiNi_0.8Co_0.15Al_0.05O₂ (LNCA) cathode material with excellent electrochemical performance for lithium-ion batteries is successfully synthesized with the precursor of Ni_0.8Co_0.15Al_0.05(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·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 Ni_0.8Co_0.15Al_0.05(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. LiNi_0.8Co_0.15Al_0.05O₂ 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 LiNi_0.8Co_0.15Al_0.05O₂ cathode material can be synthesized by a more environmentally friendly method.