Synthesis and Mechanism of High Structural Stability of Nickel-Rich Cathode Materials by Adjusting Li-Excess

Abstract

It has been a long-term challenge to improve the phase stability of Ni-rich LiNi x Mn y Co 1−x−y O 2 (x ≥ 0.6) transition metal (TM) oxides for large-scale applications. Herein, a new structure engineering strategy is utilized to optimize the structural arrangement of Li 1+x (Ni 0.88 Mn 0.06 Co 0.06 ) 1−x O 2 (NMC88) with a different Li-excess content. It was found that structure stability and particle sizes can be tuned with suitable Li-excess contents. NMC88 with an actual Li-excess of 2.7% (x = 0.027, Li/TM = 1.055) exhibits a high discharge capacity (209.1 mAh g −1 at 3.0−4.3 V, 0.1 C) and maintains 91.7% after the 100th cycle at 1 C compared with the NMC88 sample free of Li-excess. It also performs a delayed voltage decay and a good rate capacity, delivering 145.8 mAh g −1 at a high rate of 10 C. Multiscale characterization technologies including ex/in situ X-ray diffraction (XRD), focused ion beam (FIB) cutting-scanning electronic microscopy (SEM), and transmission electron microscopy (TEM) results show that a proper Liexcess (2.7%) content contributes to the formation of a broader Li slab, optimized cation mixing ratio, and even particle sizes. Therefore, NMC88 with a proper Li-excess is a good choice for next-generation cathode materials.

A Review of Degradation Mechanisms and Recent Achievements for Ni‐Rich Cathode‐Based Li‐Ion Batteries

“…Chu and co‐workers recently investigated the influence of the Li‐excess during calcination on the Li/TM mixing. [ 35 ] The schematic diagram shown in Figure 6 a shows that the samples prepared with Li/TM ratios of 1.00, 1.06, and 1.12 are denoted by E00, E06, and E12, respectively. It is found that the Li slab in the lattice will experience shrinkage under both Li‐loss (E00) and Li‐excess (E12) conditions.…”

“…a) Reproduced with permission. [ 35 ] Copyright 2020, American Chemical Society. b) Reproduced with permission.…”

Insight into structural and electrochemical properties of Mg‐doped LiMnPO 4 /C cathode materials with first‐principles calculation and experimental verification

“…1 However, as a single power source, LIB requires it to be able to store and release higher energy, which puts forward higher requirements for the energy density of battery materials, especially cathode materials. [2][3][4][5][6] Since "high voltage" cathode materials is an effective way to improve the energy density of batteries, the development of high voltage cathode materials with higher cost performance is a hot spot in the research of lithium ion batteries. [7][8][9] As far as the current research is concerned, the main research direction is LiMnNiO 4 (4.8 V) of spinel structure and LiMnPO 4 (4.1 V), LiCoPO 4 (4.8 V) and LiLiPO 4 (5.2 V) of olivine structure.…”

“…At present, lithium‐ion battery (LIB) is considered as the most potential power battery, which has been widely used in mobile electronic products, power vehicles and energy storage devices 1 . However, as a single power source, LIB requires it to be able to store and release higher energy, which puts forward higher requirements for the energy density of battery materials, especially cathode materials 2‐6 . Since “high voltage” cathode materials is an effective way to improve the energy density of batteries, the development of high voltage cathode materials with higher cost performance is a hot spot in the research of lithium ion batteries 7‐9 …”

Comparative Study on Supercapacitive Performances of Hierarchically Nanoporous Carbon Materials With Morphologies From Submicrosphere to Hexagonal Microprism

“…With the development of industry and economy of human society, environmental and energy problems have been becoming more and more serious. Developing a new energy of environmental protection and pollution-free and achieving greater energy efficiency are the important means to solve this problem (Liu Z. X. et al, 2016;Qi et al, 2019;Yu Z. L. et al, 2019;Zhu et al, 2019a,b). Supercapacitor as an environmentally friendly energy storage device has been demonstrated to be superior to traditional capacitors and rechargeable batteries, due to the high power density, fast storage and release energy rate, and long cycle stability (Xie et al, 2016(Xie et al, , 2018Hossain et al, 2017;Zhang Z. T. et al, 2017;Yao et al, 2018;Wei et al, 2020a).…”