Surface Architecture Design of LiNi_0.8Co_0.15Al_0.05O₂ Cathode with Synergistic Organics Encapsulation to Enhance Electrochemical Stability

Abstract

Ni‐rich LiNi0.8Co0.15Al0.05O2 (NCA) material attracts extensive attention due to its high discharge specific capacity, but its distinct drawbacks of rapid capacity decline and poor cycle performance at elevated temperatures and high voltage during charge/discharge cycling restricts its widespread application. To solve these problems, a multifunctional coating layer composed of a lithium‐ion‐conductive lithium polyacrylate (LiPAA) inner layer and a cross‐linked polymer outer layer from certain organic substances of silane‐coupling agent (KH550) and polyacrylic acid (PAA) is successfully designed on the surface of NCA materials, which is favorable for eliminating residual lithium and improving lithium‐ion conductivity, surface stability, and hydrophobicity of NCA materials. In addition, the amount of the coating material is also investigated. A series of characterization methods such as XRD, FTIR, SEM, TEM, and X‐ray photoelectron spectroscopy are used to analyze the morphologies and structures for materials of pristine and modified NCA. It is revealed that the co‐coating layer plays a vital part in reducing the surface residual alkalis and improving the stability of NCA particles; as a result, the modified NCA exhibits a greatly improved rate capability, cycle performance, and low polarization impedance.

Enhancing the long-cycling performance of a LiNi0.8Co0.15Al0.05O2@LaNiO3 cathode material by surface modification

“…7a and b exhibit the first three cycles in the voltage range of 3.0–4.5 V. The peak position in the CV curve corresponds to the oxidation–reduction reaction of the extraction/insertion of Li + and the valence conversion of Ni 2+ /Ni 4+ . 33,34 It can be seen that the CV patterns of the two cathode materials are basically the same, indicating that the two materials have the same redox reaction. More importantly, the difference between the corresponding voltages of the reduction peak and the oxidation peak (Δ V ) in the CV curves can indicate the degree of polarization and reversibility of the electrode materials during the oxidation–reduction reaction.…”

Prospects of polymer coatings for all solid-state and emerging Li-ion batteries

“…The Ni-rich layered oxides LiNi 1−x−y Co x Mn y O 2 (NCM, Ni > 60%) have serious safety concerns, especially in a charged state. 42,[80][81][82][83][84][85][86][87] PANI-PVP-NCM 811 shows improvement in safety characteristics with the increase of onset decomposition temperature in the presence of the coating.…”

Molecular‐Scale Hydrophobic Modification of Ni‐Rich Cathode Materials Toward Superior Critical Endurability and Environmental Stability

“…Consequently, doping and surface modification are used to reduce the formation of residual lithium compounds by changing the chemical circumstances. [22][23][24][25][26][27] However, practical applications require an easier method with more ability to control the formation of residual lithium compounds. Building a hydrophobic coating can isolate the bulk materials from the moisture and carbon dioxide in the air, suppressing the amount of residual lithium compounds formed.…”