Effects of Co/Mn Content Variation on Structural and Electrochemical Properties of Single-Crystal Ni-Rich Layered Oxide Materials for Lithium Ion Batteries

Abstract

The development of single-crystal nickel-rich layered LiNi x Co y Mn 1−x−y O 2 materials (S-NCMs) represents the most significant progress for the electrification applications of nickel-rich ternary materials. There has been prior research on the important role of transition metal elements in agglomerated materials, supplemented by surface and internal lattice optimization to drive the performance improvements. However, studies on S-NCMs, especially on the role of transition metals (TM, i.e., Co and Mn), have not been reported. In this study, we synthesized four kinds of S-NCMs with different Co/Mn contents and studied their structural, electrochemical, kinetic, and thermodynamic properties with different Co/Mn contents. The results were as follows: (1) Electrochemically, Co was more effective than Mn at 25 °C at enhancing the intercalation/deintercalation kinetics, which resulted in an increased discharge capacity, an improved rate capability, and a reduced energy loss. (2) Thermodynamically, Mn was more effective at maintaining a higher thermal stability than Co, especially at a low cutoff voltage, but at a high cutoff voltage, the difference between the action of Co and Mn decreased. The main finding of this work was the enhanced structural stability provided by Co, which could be attributed to the following: (i) the absence of the H2/H3 phase transformation when Co exceeded 15%, which inhibited the irreversible phase transformation and reduced the volume strain, and (ii) the lower degrees of decrease in the cell parameters a and c with higher contents of Co, which contributed to a low cracking degree along the (003) crystal plane. The current work provides an important reference for the single-crystallization strategy of nickel-rich materials.

Durable and Adjustable Interfacial Engineering of Polymeric Electrolytes for Both Stable Ni‐Rich Cathodes and High‐Energy Metal Anodes

“…[ 53 ] The SIP presents an inhibitory effect on these deteriorations in comparison of the TiP. From the XPS spectra, the SIP contributes to maintain the uniformity of polyether/LiTFSI components at the NCM interface, as well as promotes the generation of LiF in the CEI layer, [ 54 ] demonstrated by the C 1s and F 1s spectra ( Figure a,b and Figure S21a,b (Supporting Information)). The C 1s spectra also probes the OCO peak (290.0 eV) formed by the oxidation of polyether components in both cases (Figure 4a,b).…”

Scope and significance of transition metal oxide nanomaterials for next-generation Li-ion batteries

“…4,43,89,90 Along with the Li salts, several other Na and K-based salts are utilized to create a eutectic mixture to lower the melt temperature, promote better Li + diffusion in the crystal, and optimize the surface facets and morphology. 26,50,53,[91][92][93][94][95] Many researchers have recently shifted their attention toward nanomaterials, where the material exists in the nanoscale dimension o 1 mm or one of its critical facets grown in a direction, neglecting other dimensional facets in the nanoregime. 9,77,96,97 Nanomaterials (NM) have the advantage of being grown into a monodisperse, single-crystal morphology from the bottom-up by arranging the atoms perfectly or deconstructing microparticles by applying external energy.…”

Thermal Expansion Neutralization Enhancing the Cycling Stability of Ni-Rich LiNi0.6Co0.2Mn0.2O2 Cathode Material

“…Especially, further investigation of the thermal neutralization effect of the electrode composited with NTE materials could contribute to the current research of batteries' thermal safety characteristics. 28,29 Based on the abovementioned issues, it is indispensable to reevaluate and elucidate the specific contribution of NTE materials on the performance improvement of cathode materials from the quantitative and qualitative analyses. Herein, an appropriate NTE material LiZr 2 (PO 4 ) 3 (LZPO) with a negative thermal expansion coefficient (TEC) of 4.0 × 10 −6 K −1 in a wide temperature range from −200 to 500 °C is selected to decorate the particle surface of the NCM622 cathode material (with a TEC of 6.2 × 10 −5 K −1 ).…”

“…From the quantitative view, a comprehensive study about the volumetric expansion of the Ni-rich active electrode decorated with the NTE material is needed to clearly understand the intrinsic NTE neutralization mechanism (e.g., expansion coefficient) of the accurate regulation of microstructure evolution in the bulk active electrode. Especially, further investigation of the thermal neutralization effect of the electrode composited with NTE materials could contribute to the current research of batteries’ thermal safety characteristics. , …”