Conditioning of Li(Ni,Co)O₂ Cathode Materials for Rechargeable Batteries During the First Charge‐Discharge Cycles

Abstract

As‐prepared Li(Ni,Co)O2 with good electrochemical performance is an insulator with low degree of cation disorder, i.e. Li and (Ni,Co) are distributed on different and alternating layers. Lithium extraction in the first cycle induces an irreversible first‐order phase transition into a metallic phase with a discontinuous change in the c/a ratio by 3.6% and an accompanied partial occupation of some of the vacant Li‐sites by Ni‐ions. The specific arrangement of those Ni‐ions on Li‐layers is proposed as a key feature for the good cycling behaviour of Li(Ni,Co)O2 based cathodes in rechargeable batteries.

Anisotropic Lattice Strain and Mechanical Degradation of High- and Low-Nickel NCM Cathode Materials for Li-Ion Batteries

“…Microstrain parameter S 202 determined for NCM111 and NCM811 indicates that the crystalline lattice is significantly strained at high voltage. This may lead to imperfections such as stacking faults and their accumulation eventually may cause mechanical degradation. , Active material fracture is inevitably accompanied by the formation of (new) reactive surfaces and detrimental side reactions with the electrolyte. In addition, it may also lead to a loss of electrical contact of the active electrode regions, all of which helps to explain the cycling data shown above.…”

“…Besides the net volume changes, it is also important to consider microstrain effects during cycling. The microstrain can be estimated by analyzing the XRD line broadening. ,, The diffraction patterns in Figure (see also Figures S5 and S6) clearly indicate such line broadening, which varies nonmonotonically with the diffraction angle. The broadening is most significant for the 10 l and 01 l reflections (i.e., for 015, 107, and 018).…”

Role of fluorine surface modification in improving electrochemical cyclability of concentration gradient Li[Ni0.73Co0.12Mn0.15]O2 cathode material for Li-ion batteries

“…In addition, the initial coulombic efficiency is slightly decreased aer F modi-cation, which should be attributed to the increased cation mixing, because it has been reported that the cation mixing leads to the irreversible capacity loss. 31 Fig. 7b and the ESI † show the initial differential capacity proles (dQ/dV) for the pristine and FMCG Li[Ni 0.73 Co 0.12 Mn 0.15 ]O 2Àx F x (x ¼ 0.01, 0.02, 0.03, 0.05, 0.10 and 0.15) cathodes.…”

Fatigue Process in Li-Ion Cells: An In Situ Combined Neutron Diffraction and Electrochemical Study

“…In this sense more complete understanding of structural processes can be obtained by in-situ studies of battery materials during electrochemical cycling, when all these drawbacks can be minimized. [12][13][14][15] A typical lithium-ion cell is based on a carbon anode (negative electrode), whilst for the cathode (positive electrode) there is a selection of materials determining the battery performance at given conditions. Thus either pure or doped lithium cobalt dioxide (Li x CoO 2 ), lithium manganese dioxide (Li x Mn 2 O 4 ), lithium iron phosphate (LiFePO 4 ) usually serve as cathodes in Li-ion batteries, whose performance is directly related to the Li extraction/insertion kinetics into the lattice during the charge/discharge of the battery and the development of the structural distortions and phase transformations is of primary importance.…”