Implications of cation-disordered grain boundaries on the electrochemical performance of the LiNi_0.5Co_0.2Mn_0.3O₂ cathode material for lithium ion batteries

Abstract

The electrochemical properties of Li(NixCoyMnz)O2 (NCM) materials are decisively determined by the interplay of combined disordering of cations and the relevant chemical/electronic changes.

Surface/Interface Structure Degradation of Ni‐Rich Layered Oxide Cathodes toward Lithium‐Ion Batteries: Fundamental Mechanisms and Remedying Strategies

“…As discussed above, the content of Li residues and the level of cation disorder depend highly on the synthetic conditions, particularly for the contributions from the particle size, [64,205] Liexcess content, [125,207,232,233] calcination temperature, [203,207,234] calcination atmosphere, [235,236] and heating/cooling rate. In particular, Wang et al investigate the kinetic and thermodynamic aspects of cationic ordering during synthesis of Ni-rich cathodes by adjusting the sintering temperature and time.…”

“…Adjusting the ratio of lithium to TM ions during the synthesis process is also a simple yet critical approach to control the cation disorder degree in Ni-rich cathodes. [125,232,233,237] Representatively, the Li-content-dependent cation disorder phenomenon near the grain boundary of the NCM523 particles using atom-resolved chemical and valence mapping techniques is unraveled, showing that the cation disorder phenomenon near the grain boundary is conclusively dependent on the ratio of lithium to TM ions, which plays a crucial role in determining the valence states of Ni and Co ions migrating into the Li layer (Figure 12d,e), thus tuning the level of cation disorder. [233] It should be specially noted that the optimized synthetic conditions, particularly for the sintering temperature and the ratio of lithium to TM ions, depend largely on specific compositions of the Ni-rich cathodes.…”

Nano-TiO2 coated single-crystal LiNi0.65Co0.15Mn0.2O2 for lithium-ion batteries with a stable structure and excellent cycling performance at a high cut-off voltage

“…They have been of research interest for more than 20 years because of their high specic capacity, high voltage, low price, good rate performance, and other advantages. [1][2][3][4][5] The discharge capacity of NCM is positively correlated with the nickel content, which means that nickel-rich materials (NCM622 (60% Ni) and NCM811 (80% Ni)) can better meet researchers' pursuit of high specic capacity. [6][7][8][9] Although these two materials have been or are being used in the automotive eld, various problems still hamper their practical application.…”

Hierarchically Structured Core–Shell Design of a Lithium Transition-Metal Oxide Cathode Material for Excellent Electrochemical Performance

“…53−55 This characteristic can be utilized as an indicator of the charge state change in battery materials. 47,56 To map the spatial distribution of the oxidation states of the TMs in the primary particles of samples C1 and C2, we measured the intensity ratio of the L 3 and L 2 peaks of the L edges of Ni, Co, and Mn from the EELS SI data cube, 57 which can be performed utilizing an open-source software package called "Oxide Wizard". 58 The reliability of the charge state measure- ments was verified by performing the same EELS analysis routine on known samples.…”