Enhanced Interfacial Kinetics and High Rate Performance of LiCoO₂ Thin-Film Electrodes by Al Doping and In Situ Al₂O₃ Coating

Abstract

The structure and surface-interface instability of LiCoO 2 thin-film electrodes during charge–discharge cycles are one of the main factors leading to the deterioration of electrochemical performance. Element doping and surface coating are effective strategies to tackle this issue. In this work, Al-doped and in situ Al 2 O 3 -coated LiCoO 2 composite thin-film electrodes are prepared by magnetron sputtering. The results show that the resultant composite thin-film electrodes exhibited excellent cycling stability, with a discharge specific capacity of 40.2 μAh um –1 cm –2 after 240 cycles at 2.5 μA cm –2 , with a capacity retention rate of 94.14%, compared to a discharge capacity of the unmodified sample of only 37.7 μAh um –1 cm –2 after 110 cycles, with a capacity retention rate of 80.04%. In addition, the rate performance of the prepared LiCoO 2 film is significantly improved, and the discharge specific capacity of the Al-doped sample reaches 43.5 μAh um –1 cm –2 at 100 μA cm –2 , which is 38.97% higher than that of the unmodified sample (31.3 μAh um –1 cm –2 ). The enhancement of electrochemical performance is mainly attributed to the synergistic effect of Al doping and in situ Al 2 O 3 coating. The metal Al forms a conductive network in the film, while part of the Al will enter the LiCoO 2 lattice to form a LiAl y Co 1– y O 2 solid solution, promoting the transport of lithium ions and improving the stability of the electrode structure. The in situ continuous deposition of the coating optimizes the active material coating–electrolyte interface.

Short‐Process Regeneration of Highly Stable Spherical LiCoO2 Cathode Materials from Spent Lithium‐Ion Batteries through Carbonate Precipitation

“…The spectrum can be divided into a peak of 73.3 eV attributed to Al 2 O 3 and a solid solution peak located at ~71.2 eV, indicating that Al 3+ ions exist in both Al 2 O 3 form and solid solution form in LCAO. The O 1s spectra can be divided into two peaks around ~529.5 eV and 532 eV (Figure 3d), respectively, corresponding to the bonds in metallic oxygen bond (Co−O) and nonmetallic oxygen bond (C=O/C−O) forms, [10a,14] respectively. After fitting, it is found that the proportion of the former increases gradually and then decreases when the temperature rises to 950 °C.…”

Toward Direct Regeneration of Spent Lithium-Ion Batteries: A Next-Generation Recycling Method

“…Aluminum and copper are the most studied elements among the existing studies on the influence of impurities in the battery recycling process, because they are current collectors and are most likely to remain in the cathode materials after being broken and separated. Aluminum is generally regarded as a beneficial element and is used as a dopant in many studies to improve the high-voltage performance of cathodes . The used compounds include alumina, aluminum fluoride, LiAlH 4 , etc.…”

“…Aluminum is generally regarded as a beneficial element and is used as a dopant in many studies to improve the high-voltage performance of cathodes. 302 The used compounds include alumina, 303 aluminum fluoride, 304 LiAlH 4 , 305 etc. Aluminum element can form a coating layer on the surface of the cathode particles and resist the erosion of fluorine-containing compounds in the electrolyte, thus prolonging the lifespan of the cathode.…”

Aluminum-Doped Lithium-Vacant Layered Li1–xCr1–xAlxO2: A Potentially Active Electrocatalyst for the Oxygen Evolution Reaction

“…The Al 2p core level spectrum (Figure 4c) consists of a peak at about 74.5 eV that is close to the binding energy of Al 3+ in LiAlO 2 . 51 In addition, a shakeup peak located at about 79.2 eV is also present due to defects present in the lattice. 52,53 The deconvoluted Li 1s spectra, shown in Figure 4d,e, are fitted with two peaks located at ∼54.3 and ∼55.6 eV, which confirm the existence of lithium in two different cation environments (i.e., the octahedral Cr 3+ polyhedra and the interstitial Cr 6+ tetrahedra, respectively) in the lattice.…”