Relationship of Chemical Composition and Moisture Sensitivity in LiNixMnyCo1−X−YO2 for Lithium-Ion Batteries

Abstract

Chemical composition – moisture sensitivity relationship of LiNixMnyCo1-x-yO2 (NMC) cathode materials was investigated by exploring crystal structures, surface properties and electrochemical performance behaviors of various commercial NMC powders: LiNi1/3Mn1/3Co1/3O2 (NMC111), LiNi0.5Mn0.3Co0.2O2 (NMC532), LiNi0.6Mn0.2Co0.2O2 (NMC622), and LiNi0.8Mn0.1Co0.1O2 (NMC811). The NMC powders were stored in different moisture conditions: moisture-free, humidified air, or immersed in water. Rietveld refinement analysis of X-ray diffraction (XRD) data and scanning electron microscopy (SEM) were used to characterize the crystal structure changes and the evolution of particle surfaces morphologies. The effect of moisture contamination on the electrochemical properties of NMC cathodes were studied by galvanostatic cycling and electrochemical impedance spectroscopy (EIS). The moisture contamination resulted in either structural disorder or unwanted surficial deposition products, which increased a charge-transfer impedance and consequent performance degradation of battery cells. The results showed that NMC's moisture vulnerability increased with Ni content (x) despite protective coatings on commercial particles, which stressed the necessity of alternative surface passivation strategies of Ni-rich NMC for broad applications such as electric vehicles (EVs) and electrified aircraft propulsion (EAP).

Li0.5La0.5TiO3 as an Ionic Conducting Additive Enhancing the High-Voltage Performance of LiNi0.8Mn0.1Co0.1O2 Cathodes in Lithium-Ion Batteries

“…In contrast to the bare NMC cathodes, the cathodes blended with LLTO demonstrated more stable voltage profiles and exhibited relatively lower voltage drops during the 300 cycles. The d Q /d V profiles of both the NMC811 + 1 wt % LLTO and NMC811 + 5 wt % LLTO cathodes exhibited distinct peaks at around 3.7, 3.8, and 4.25 V vsLi , which are associated with multiple phase transformations [i.e., H1 – >monoclinic (M) – >H2 – >H3] of NMC . The enhanced performance of the LLTO–NMC811 cathodes can be attributed to two primary factors.…”

“…In a prior study, we reported that full-cells with nickel-rich layered cathodes and graphite anodes demonstrated poor cyclability, particularly at higher nickel content and higher operating voltages. 21,28 Full-cell cycles at high voltage resulted in a series of phase transitions and associated mechanical stress and parasitic reactions at the CEI for the cathodes. The resulting byproducts such as dissolved transition metals (such as Mn and Ni ions) and HF migrate to anodes by an electric field and attack the graphite SEI, leading to destabilization of the SEI and triggering additional parasitic reactions.…”

“…The dQ/dV profiles of both the NMC811 + 1 wt % LLTO and NMC811 + 5 wt % LLTO cathodes exhibited distinct peaks at around 3.7, 3.8, and 4.25 V vsLi , which are associated with multiple phase transformations [i.e., H1 − >monoclinic (M) − >H2 − >H3] of NMC. 28 The enhanced performance of the LLTO−NMC811 cathodes can be attributed to two primary factors. First, the addition of LLTO improves the overall ionic conductivity of the CEI layer.…”

Nanosecond Laser Annealing of NMC 811 Cathodes for Enhanced Performance

“…It should be mentioned that the moisture and prolonged storage of these electrodes results in a severe accumulation of surface carbonates. 47,48 The carbonate species produced during ambient exposure of NMC 811 are electrochemically inactive with poor electronic conductivity, which hinders Li diffusion significantly, 49,50 resulting in the capacity fade as seen in Fig. 6.…”

Enabling Ambient Stability of LiNiO2 Lithium-Ion Battery Cathode Materials via Graphene–Cellulose Composite Coatings

“…In this work, we address the aforementioned issues of ambient-reactive Ni-rich layered oxides via a hydrophobic coating layer composed of graphene and ethyl cellulose (GrEC). We demonstrate this scheme for LNO because it represents the Ni-rich limit with the highest ambient sensitivity in the family of Ni-rich layered oxides. ,, Ethyl cellulose (EC) is an attractive materials choice because it is hydrophobic − and can be scalably coated onto cathode material surfaces via solution-phase methods. EC can also be pyrolyzed thermally or photonically, enabling its removal immediately preceding electrochemical cycling.…”