Journal
CHEMICAL ENGINEERING JOURNAL
Volume 438, Issue -, Pages -Publisher
ELSEVIER SCIENCE SA
DOI: 10.1016/j.cej.2022.135537
Keywords
Ni-rich cathode; Layered material; F- doping; Structural stability; Lithium-ion battery
Categories
Funding
- National Natural Science of China [51874046]
- Outstanding Youth of Hubei Province [2020CFA090]
- Young Top-notch Talent Cultivation Program of Hubei Province
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The introduction of F doping is an important approach to improve the structure and performance of Ni-rich oxides for cathode materials.
Layered Ni-rich oxides have always been considered as highly promising cathode materials for high-energy-density lithium-ion batteries, whereas they have been confronted with technical bottlenecks sprung from short cycle life and thermal instability. In this work, F- doping as one feasible approach has been introduced intoLiNi(0.8)Co(0.15)Al(0.05)O(2) for alleviating the limitations by stabilizing the layered structure. The stoichiometric LiNi0.8Co0.15Al0.05O2-xFx (0 < x < 0.1) composite powders doped with different amounts of NH4F powders are precisely synthesized by in-situ modified method, which are strictly identified by physicochemical methods. The characterization results demonstrate that F ions successfully enter into the lattice of LiNi0.8Co0.15Al0.05O2-xFx (0 <= x <= 0.1) and that the targeted LiNi0.8Co0.15Al0.05O1.96F0.04 composite powders possess the most ordered layered structure with compact surface morphology when the doping amount of F- is up to 4 % based on the weight of the precursor Ni0.8Co0.15Al0.05(OH)(2) composite powders. Moreover, the half-cell assembled with the LiNi0.8Co0.15Al0.05O1.96F0.04 composite electrode presents a reversible discharge specific capacity of 157.8 mAh g(-1) with remarkable capacity retention of 98.3 % after 100cycles at 2.0C at 25 degrees C. Even at an elevated temperature of 60 degrees C and a high current density of 5.0C, it still delivers an improved discharge specific capacity of 142.6 mAh g(-1) with excellent capacity retention of 89.1 %. The outstanding improvements in the terms of the lithium storage performance are principally attributed to the stronger metal-F bonds substituting the metal-O bonds with introducing F ions into the lattice, which can not only effectively stabilize the host structure to preserve the structural integrity, but also prevent the erosion of HF and suppress the increment of the polarization degree during continuous cycling processes. Therefore, the F- doping strategy may provide a novel horizon to construct layered Ni-rich cathode materials with improved structural stability and durable electrochemical performance for lithium-ion batteries.
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