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·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.

•Sodium additive induced a dispersed secondary phase with structure of Na0.7MnO2.05.•The two-phase composite showed improved rate performance.•Sodium additive enhanced electrical conductivity and lithium ionic conductivity.•The sodium in the Na0.7MO2.05 can be activated for the transportation of Li+.The effects of sodium additive on the microstructure and electrochemical properties of Li[Li0.2Mn0.54Ni0.13Co0.13]O2-based material have been investigated. XRD patterns show that the sodium additive doesn't incorporate into the Li[Li0.2Mn0.54Ni0.13Co0.13]O2 lattice, but induces a dispersed secondary phase with the structure of Na0.7MnO2.05. The two-phase composite shows an improved rate performance in comparison with the single phase of Li[Li0.2Mn0.54Ni0.13Co0.13]O2, which can be attributed to the enhanced electrical conductivity and lithium ion diffusion. The interfaces between Li[Li0.2Mn0.54Ni0.13Co0.13]O2 and the secondary phase provide fast diffusion paths for Li+. DC electrical conductivity and EIS are used to elucidate the phenomenon.

Micro-spherical particle of Ni–Mn–Co alloy was synthesized by powder metallurgy pulverization (PMP) method with Ni, Co and Mn metal as raw materials. Then spherical and dense LiNi1/3Mn1/3Co1/3O2 particle with well-ordered layered structure is obtained by calcining the oxide of Ni–Mn–Co alloy and Li2CO3. The as-prepared material was characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and electrochemical tests. LiNi1/3Mn1/3Co1/3O2 prepared here indicated an initial discharge capacity of 164.4 mAh g−1 at 0.1 C rate within the voltage range of 2.8–4.3 V. The novel method showed high efficiency and environmental friendly for industrialization.

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·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.