ELECTROCHEMISTRY AND STRUCTURAL CHEMISTRY OF LINIO2 (R(3)OVER-BAR-M) FOR 4 VOLT SECONDARY LITHIUM CELLS

The synthesis and characterization of LiNiO2 for a 4 V secondary lithium cell was done. The LiNiO2 was prepared by ten different methods and characterized by x-ray diffraction and electrochemical methods. LiNiO2 prepared from LiNO3 and NiCO3 [or Ni(OH)2] exhibited more than 150 mAh . g-1 of rechargeable capacity in the voltage range between 2.5 and 4.2 V in 1M LiClO4 propylene carbonate solution. The reaction mechanism was also examined and explained in terms of topotactic reaction. Lithium nickelate(III) (R3mBar; a = 2.88 angstrom, c = 14.18 angstrom in hexagonal setting) was oxidized to nickel dioxide (R3mBAR; a = 2.81 angstrom, c = 13.47 angstrom) via Li1-xNiO2 (0.25(2) less-than-or-equal-to x less-than-or-equal-to 0.55(2)) having a monoclinic lattice (C2/m). The nickel dioxide could be reversibly reduced to lithium nickelate(III). Factors affecting the electrochemical reactivity of LiNiO2 are given and the possibility of using LiNiO2 for 4 V secondary lithium cells is described.