Ultrathin Al2O3 Coating on LiNi0.8Co0.1Mn0.1O2 Cathode Material for Enhanced Cycleability at Extended Voltage Ranges

Abstract

Ni-rich LiNi0.8Co0.1Mn0.1O2 oxide has been modified by ultrathin Al2O3 coatings via atomic layer deposition (ALD) at a growth rate of 1.12 Å/cycle. All characterizations results including TEM, SEM, XRD and XPS together confirm high conformality and uniformity of the resultant Al2O3 layer on the surface of LiNi0.8Co0.1Mn0.1O2 particles. Coating thickness of the Al2O3 layer is optimized at ~2 nm, corresponding to 20 ALD cycles to enhance the electrochemical performance of Ni-rich cathode materials at extended voltage ranges. As a result, 20 Al2O3 ALD-coated LiNi0.8Co0.1Mn0.1O2 cathode material can deliver an initial discharge capacity of 212.8 mAh/g, and an associated coulombic efficiency of 84.0% at 0.1 C in a broad voltage range of 2.7–4.6 V vs. Li+/Li in the first cycle, which were both higher than 198.2 mAh/g and 76.1% of the pristine LiNi0.8Co0.1Mn0.1O2 without the Al2O3 protection. Comparative differential capacity (dQ/dV) profiles and electrochemical impedance spectra (EIS) recorded in the first and 100th cycles indicated significant Al2O3 ALD coating effects on suppressing phase transitions and electrochemical polarity of the Ni-rich LiNi0.8Co0.1Mn0.1O2 core during reversible lithiation/delithiation. This work offers oxide-based surface modifications with precise thickness control at an atomic level for enhanced electrochemical performance of Ni-rich cathode materials at extended voltage ranges.

Improved cyclability of Nickel-rich layered oxides

“…Al 2 O 3 ) is often reported. [13,14] Other strategies include functional electrolyte additives, alternative solvents with higher oxidative stability, and core-shell or concentration gradient structures. [12,15,16,17] Lately, micron sized single crystalline layered oxides have gained attention as they can alleviate excessive surface exposure from grain boundary cracking.…”

Surface Modification Strategies for Improving the Cycling Performance of Ni‐Rich Cathode Materials

“…This sets ALD apart from chemical bath deposition or line‐of‐sight techniques, such as physical vapor deposition, which create thicker films on the surface of particles but do not reach into pores and cracks of rough surfaces of the CAM secondary particles. For Ni‐rich NCMs and NCAs, the technique has been used to deposit Al 2 O 3 ,, LiAlO 2 , LiAlF 4 , Li 3 PO 4 and TiO 2 . However, many of the available ALD coating materials and routes are unexplored to date or have only been tested for low‐Ni CAMs.…”

ZnO Interface Modified LiNi0.6Co0.2Mn0.2O2 Toward Boosting Lithium Storage

“…[ 15,16 ] Until now, scientists have made a lot of efforts and scientific research to improve the electrochemical characteristics, finally, the surface coating proved to be an effective method. It has been reported that coating inorganic compounds such as metal oxides (SiO 2 , [ 17 ] WO 3 , [ 18 ] Co 3 O 4 , [ 19 ] ZrO 2 , [ 20 ] ZnO [ 21 ] , and Al 2 O 3 [ 22,23 ] ), phosphates (Mn 3 (PO 4 ) 2 [ 24 ] ), and fluorides (AlF 3 [ 25 ] ) effectively improve the structural stability of the cathode. It can also inhibit the dissolution of transition metal ions in the electrode by avoiding direct contact between the electrode and the electrolyte, and it can also avoid the destruction of the material structure during charging and discharging.…”