Ni-Rich Layered Oxide with Preferred Orientation (110) Plane as a Stable Cathode Material for High-Energy Lithium-Ion Batteries

Abstract

The cathode, a crucial constituent part of Li-ion batteries, determines the output voltage and integral energy density of batteries to a great extent. Among them, Ni-rich LiNixCoyMnzO2 (x + y + z = 1, x ≥ 0.6) layered transition metal oxides possess a higher capacity and lower cost as compared to LiCoO2, which have stimulated widespread interests. However, the wide application of Ni-rich cathodes is seriously hampered by their poor diffusion dynamics and severe voltage drops. To moderate these problems, a nanobrick Ni-rich layered LiNi0.6Co0.2Mn0.2O2 cathode with a preferred orientation (110) facet was designed and successfully synthesized via a modified co-precipitation route. The galvanostatic intermittent titration technique (GITT) and electrochemical impedance spectroscopy (EIS) analysis of LiNi0.6Co0.2Mn0.2O2 reveal its superior kinetic performance endowing outstanding rate performance and long-term cycle stability, especially the voltage drop being as small as 67.7 mV at a current density of 0.5 C for 200 cycles. Due to its unique architecture, dramatically shortened ion/electron diffusion distance, and more unimpeded Li-ion transmission pathways, the current nanostructured LiNi0.6Co0.2Mn0.2O2 cathode enhances the Li-ion diffusion dynamics and suppresses the voltage drop, thus resulting in superior electrochemical performance.

Reactivity at the Electrode–Electrolyte Interfaces in Li-Ion and Gel Electrolyte Lithium Batteries for LiNi0.6Mn0.2Co0.2O2 with Different Particle Sizes

“…The layered oxide LiNi 0.6 Mn 0.2 Co 0.2 O 2 (NMC622) is a very attractive positive electrode material as already extensively reported, with its good reversible capacity (up to 180–190 mAh/g), chemical stability, and cyclability upon long-range cycling in Li-ion batteries. − Recently, we explored a large panel of synthesis conditions to tailor the primary particle size of NMC622 powders from 170 nm to 2.1 μm . Their electrochemical performance in Li-ion batteries and surface reactivity were found to be highly sensitive to cycling conditions (C-rates and potential windows), as well as to primary particle size.…”

Determining the Preferred Orientation of Silver-Plating via X-ray Diffraction Profile

“…Practically, polycrystalline plating films reveal some degree of preferred orientation owing to the forces evolving crystal growth [ 1 , 2 , 3 ]. For this reason, knowledge of the evolution of preferred orientations can provide valuable information to optimize the preparing process [ 4 , 5 , 6 ].…”

Unraveling the Morphological Dependency of the LiNi0.6Mn0.2Co0.2O2 Layered Oxide Reactivity in Li-Ion Batteries

“…Among all the possible compositions, the LiNi 0.6 Mn 0.2 Co 0.2 O 2 layered oxide (NMC622) was shown to be one of the best compromises to combine the beneficial effects of the Ni, Mn, and Co for good energy density, structural and thermal stability, and good cyclability, respectively . Many efforts have been made in the past 20 years to control the synthesis and properties of this material. − In order to optimize their electrochemical properties, different studies have been focused on preparing them with different morphologies (i.e., particle size or shape), especially as oriented or platelet-shaped particles in order to obtain materials that can handle fast charge. ,,,− Indeed, the platelet morphology tends to stabilize the {010} facets, that are the Li + ions diffusion pathways into the structure, so it enhances the alkali diffusion during cycling and increases the performances of the material. , A further enhancement of the electrochemical performances has been observed when these platelets are radially oriented inside secondary particles as this particular morphology is the best one to maximize the access to the diffusion paths . Such morphologies are mostly obtained by coprecipitation ,− ,, or hydrothermal synthesis ,, followed by a solid-state reaction at high temperature.…”

“…Many efforts have been made in the past 20 years to control the synthesis and properties of this material. − In order to optimize their electrochemical properties, different studies have been focused on preparing them with different morphologies (i.e., particle size or shape), especially as oriented or platelet-shaped particles in order to obtain materials that can handle fast charge. ,,,− Indeed, the platelet morphology tends to stabilize the {010} facets, that are the Li + ions diffusion pathways into the structure, so it enhances the alkali diffusion during cycling and increases the performances of the material. , A further enhancement of the electrochemical performances has been observed when these platelets are radially oriented inside secondary particles as this particular morphology is the best one to maximize the access to the diffusion paths . Such morphologies are mostly obtained by coprecipitation ,− ,, or hydrothermal synthesis ,, followed by a solid-state reaction at high temperature. Regardless of the synthesis method chosen, the growth of platelet particles requires the use of a surfactant that will adsorb preferentially on specific facets of the particles and impede the growth of the particles in one particular direction .…”

“…Regardless of the synthesis method chosen, the growth of platelet particles requires the use of a surfactant that will adsorb preferentially on specific facets of the particles and impede the growth of the particles in one particular direction . The most usual surfactants are cetyltrimethylammonium bromide, sodium dodecyl sulfate, , polyvinylpyrrolidone, − and ammonium hydroxide (NH 4 OH). ,− NH 4 OH is a reactant commonly used during coprecipitation as a chelating agent but it was shown by Hua et al that it could also play the role of a surfactant when it is used in large amount …”