In this study, we addressed the poor cycling and rate performance of LiNiO2, a material with ultrahigh nickel content considered a strong contender for high-energy-density lithium-ion battery cathodes. We introduced nano-Al2O3 during the lithiation process to achieve dual modified material through bulk phase element doping and in situ LiAlO2 coating. Comparison revealed notable improvements in the modified materials. In particular, LiNi0.99Al0.01O2 maintained a capacity retention rate of 73.1% after 300 cycles in a long-cycle test at 0.5C current density, outperforming the undoped material. In rate performance tests, the doped samples consistently exhibited higher discharge-specific capacities than that of the undoped counterpart. Notably, at a high current density of 5C, LiNi0.99Al0.01O2 exhibited a discharge-specific capacity of 101.75 mAh g–1. The results indicate that an appropriate amount of Al doping can effectively stabilize the layered structure of the cathode material and delay the irreversible phase transition from H2 to H3. Further, Al doping facilitates the formation of a LiAlO2 coating on the surface of the particles. This coating acts as a fast-ion conductor, enhancing the transport of lithium ions and reducing the erosion of the active material by the electrolyte.
Wang Li-Zhen,Yang Wei,Lv Teng-Fei,Gao Ke-Zheng,Yan Ji
In this paper, core-shell like LiAlO 2 -coated Li 1.2 Ni 0.13 Co 0.13 Mn 0.54 O 2 composite was synthesized by an improved solvothermal method. The surface of the material becomes rough after LiAlO 2 coating with a thickness of 5–10 nm. Meanwhile, the surface-coating component with the layer structure α-LiAlO 2 can change the dispersion of transition metal elements. When tested in 2.0–4.8 V at 0.05 °C, the initial discharge capacity of the LiAlO 2 -coated sample is 206.4 mAh g −1 with the columbic efficiency of 78.0%, which is higher than that of the pristine Li-rich Li 1.2 Ni 0.13 Co 0.13 Mn 0.54 O 2 sample. Further tested under 1 C rate, the coated sample possesses 151.4 mAh g −1 of specific capacity and maintains 149.0 mAh g −1 after 50 cycles with the capacity retention of 98.4%. The improved reversible capacity, rate capability, and cycling durability of the Li 1.2 Ni 0.13 Co 0.13 Mn 0.54 O 2 material are attributed to the synergistic effect of surface coating of highly Li-conductive LiAlO 2 and the fuzzy interface between LiAlO 2 and Li 1.2 Ni 0.13 Co 0.13 Mn 0.54 O 2 .
All-solid-state lithium-ion batteries (ASSLBs) employing silicon (Si) anode and sulfide electrolyte attract much attention, since they can achieve both high energy density and safety. For large-scale application, sheet-type Si anode matching sulfide based ASSLBs is preferred. Here, a LiAlO 2 layer coated Si (Si@LiAlO 2 ) is reported for sheet-type electrode. This electrode employs conventional slurry coating methods without adding any sulfide electrolyte. The effect of LiAlO 2 coating on the electrochemical performance and morphology evolution of Si electrode is investigated. Since the high mechanical strength and ionic conductivity of LiAlO 2 layer can sufficiently relieve the huge expansion of Si and promote the Li + diffusion, the electrochemical performance is significantly enhanced. The Si@LiAlO 2 electrodes deliver high coulombic efficiency exceeding 80% and hold considerable specific capacity of 1205 mAh g −1 (150 cycles, 0.33 C). The Si@LiAlO 2 | LiNi 0.83 Co 0.11 Mn 0.06 O 2 full-cells exhibit a high reversible capacity of 147 mAh g −1 (0.28 mA cm −2 ) and a considerable capacity retention of 80.2% (62 cycles, 2.8 mA cm −2 ). This work demonstrates promising practicability and provides a new route for the scalable preparation of Si electrode sheets for ASSLBs with extended lifespan.
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