Effective and Low-Cost In Situ Surface Engineering Strategy to Enhance the Interface Stability of an Ultrahigh Ni-Rich NCMA Cathode

Abstract

Ultrahigh Ni-rich quaternary layered oxides LiNi1–x–y–z Co x Mn y Al z O2 (1 – x – y – z ≥ 0.9) are regarded as some of the most promising cathode candidates for lithium-ion batteries (LIBs) because of their high energy density and low cost. However, poor rate capacity and cycling performance severely limit their further commercial applications. Herein, an in situ coating strategy is developed to construct a uniform LiAlO2 layer. The NH4HCO3 solution is added to a NaAlO2 solution to form a weak alkaline condition, which can reduce the hydrolysis rate of NaAlO2, thus enabling uniform deposition of Al(OH)3 on the surface of a Ni0.9Co0.07Mn0.01Al0.02(OH)2 (NCMA) precursor. The LiAlO2-coated samples show enhanced cycling stability and rate capacity. The capacity retention of NCMA increases from 70.7% to 88.3% after 100 cycles at 1 C with an optimized LiAlO2 coating amount of 3 wt %. Moreover, the 3 wt % LiAlO2-coated sample also delivers a better rate capacity of 162 mAh g–1 at 5 C, while that of an uncoated sample is only 144 mAh g–1. Such a large improvement of the electrochemical performance should be attributed to the fact that a uniform LiAlO2 coating relieves harmful interfacial parasitic reactions and stabilizes the interface structure. Therefore, this in situ coating approach is a viable idea for the design of higher-energy-density cathode materials.

Enhancing the Integral Structural and Thermal Stability of Ultrahigh-Ni Cathodes via Morphology Refinement and In Situ Interfacial Engineering

“…From the perspective of dynamics, the galvanostatic intermittent titration technique (GITT) is used for testing the lithium-ion diffusion coefficient of different materials. , Figure a,b roughly expresses the same trend in the lithiation process: D Li + rises rapidly from work voltage at 3.6 V, then drops rapidly about 4.15 V, and finally keeps gently until 4.3 V, where two dramatic changes of D Li+ correspond to two phase transitions (H1 → M and H2 → H3). The overall D Li+ of the pristine sample is slightly inferior to NCM-WF2 after the first cycle, which is affected by constructed fast lithium-ion thoroughfare.…”

Damage mechanisms and recent research advances in Ni‐rich layered cathode materials for lithium‐ion batteries

“…The corrosion of the Ni-rich cathode by the electrolyte solution is prevented by covering the cathode's surface, 119 boosting the cathode's structural stability, and enhancing the lithium battery's cycle performance. 120 Li et al 121 used the wet chemical in situ deposition method to uniformly coat different concentrations of PrF 3 on the surface of NCM811 (Figure 7A), and named them Pr0.5-NCM, Pr1-NCM and Pr2-NCM, respectively.…”

Oxygen Vacancies Driven by Co in the Deeply Charged State Inducing Intragranular Cracking of Ni‐Rich Cathodes

“…[1,2] Ni-rich layered oxides (LiNi x Co y Mn 1-x-y , x ≥0.9) with a theoretical specific capacity of 274 mAh g −1 are considered as a kind of promising cathode to tackle this bottleneck. [3][4][5] However, high Ni content renders a range of risks including surface phase DOI: 10.1002/smll.202310321 transition, thermal runaway, and cracking, which restrict the practical application of Ni-rich cathodes. [6][7][8] Notably, the intragranular crack, which typically creates two free surfaces parallel to the (003) plane within the primary particle, is on a small scale but extraordinarily dense.…”