Two birds with one stone: One-pot concurrent Ta-doping and -coating on Ni-rich LiNi0.92Co0.04Mn0.04O2 cathode materials with fiber-type microstructure and Li+-conducting layer formation.

A novel scalable Taylor-Couette reactor (TCR) synthesis method was employed to prepare Ta-modified LiNi0.92Co0.04Mn0.04O2 (T-NCM92) with different Ta contents. Through experiments and density functional theory (DFT) calculations, the phase and microstructure of Ta-modified NCM92 were analyzed, showing that Ta provides a bifunctional (doping and coating at one time) effect on LiNi0.92Co0.04Mn0.04O2 cathode material through a one-step synthesis process via a controlling suitable amount of Ta and Li-salt. Ta doping allows the tailoring of the microstructure, orientation, and morphology of the primary NCM92 particles, resulting in a needle-like shape with fine structures that considerably enhance Li+ ion diffusion and electrochemical charge/discharge stability. The Ta-based surface-coating layer effectively prevented microcrack formation and inhibited electrolyte decomposition and surface-side reactions during cycling, thereby significantly improving the electrochemical performance and long-term cycling stability of NCM92 cathodes. Our as-prepared NCM92 modified with 0.2 mol% Ta (i.e., T2-NCM92) exhibits outstanding cyclability, retaining 84.5 % capacity at 4.3 V, 78.3 % at 4.5 V, and 67.6 % at 45 â„ƒ after 200 cycles at 1C. Even under high-rate conditions (10C), T2-NCM92 demonstrated a remarkable capacity retention of 66.9 % after 100 cycles, with an initial discharge capacity of 157.6 mAh g-1. Thus, the Ta modification of Ni-rich NCM92 materials is a promising option for optimizing NCM cathode materials and enabling their use in real-world electric vehicle (EV) applications.

Systematic study of Co-free LiNi0.9Mn0.07Al0.03O2 Ni-rich cathode materials to realize high-energy density Li-ion batteries.

The growing use of EVs and society's energy needs require safe, affordable, durable, and eco-friendly high-energy lithium-ion batteries (LIBs). To this end, we synthesized and investigated the removal of Co from Al-doped Ni-rich cathode materials, specifically LiNi0.9Co0.1Al0.0O2 (NCA-0), LiNi0.9Mn0.1Al0.0O2 (NMA-0), LiNi0.9Mn0.07Al0.03O2 (NMA-3), intending to enhance LIB performance and reduce the reliance on cobalt, a costly and scarce resource. Our study primarily focuses on how the removal of Co affects the material characteristics of Ni-rich cathode material and further introduces aluminum into the cathode composition to study its impacts on electrochemical properties and overall performance. Among the synthesized samples, we discovered that the NMA-3 sample, modified with 3 mol% of Al, exhibited superior battery performance, demonstrating the effectiveness of aluminum in promoting cathode stability. Furthermore, the Al-modified cathode showed promising cycle life under normal and high-temperature conditions. Our NMA-3 demonstrated remarkable capacity retention of âˆ¼ 88 % at 25 °C and âˆ¼ 81 % at 45 °C after 200 cycles at 1C, within a voltage range of 2.8-4.3 V, closely matching the performances of conventional NCM and NCA cathodes. Without cobalt, the cathodes exhibited increased cation disorder leading to inferior rate capabilities at high C-rates. In-situ transmission XRD analysis revealed that the introduction of Al has reduced the phase change and provided much-needed stability to the overall structure of the Co-free NMA-3. Altogether, the findings suggest that our aluminum-modified NMA-3 sample offers a promising approach to developing Co-free, Ni-rich cathodes, effectively paving the way toward sustainable, high-energy-density LIBs.

Preparation of long-term cycling stable ni-rich concentration-gradient NCMA cathode materials for li-ion batteries.

Nickel-rich (Ni > 90 %) cathodes are regarded as one of the most attractive because of their high energy density, despite their poor stability and cycle life. To improve their performance, in this study we synthesized a double concentration-gradient layered Li[Ni0.90Co0.04Mn0.03Al0.03]O2 oxide (CG-NCMA) using a continuous co-precipitation Taylor-Couette cylindrical reactor (TCCR) with a Ni-rich-core, an Mn-rich surface, and Al on top. The concentration-gradient morphology was confirmed through cross-sectional EDX line scanning. The as-synthesized sample exhibited excellent electrochemical performance at high rates (5C/10C), as well as cyclability (91.5 % after 100 cycles and 70.3 % after 500 cycles at 1C), superior to that (83.4 % and 47.6 %) of its non-concentration-gradient counterpart (UC-NCMA). The Mn-rich surface and presence of Al helped the material stay structurally robust, even after 500 cycles, while also suppressing side reactions between the electrode and electrolyte, resulting in better overall electrochemical performance. These enhancements in performance were studied using TEM, SEM, in-situ-XRD, XPS, CV, EIS and post-mortem analyses. This synthetic method enables the highly scalable production of CG-NCMA samples with two concentration-gradient structures for practical applications in Li-ion batteries.