Shouyi Yin,Hongyi Chen,Jun Chen,Abouzar Massoudi,Wentao Deng,Xu Gao,Shu Zhang,Ying Wang,Tsung-Wu Lin,Craig E. Banks,Shi-zhang Qiao,Guoqiang Zou,Hongshuai Hou,Xiaobo Ji
The implementation of Ni-rich cathodes with high energy density has been critically restrained by stress corrosion. Herein, crack-free LiNbO3-coated LiNi0.88Co0.10Mn0.02O2, as theoretically predicted, demonstrates highly reversible lithiation/delithiation. Mechanically, the phase transition (H1 → H2 → H3) is significantly alleviated by the excogitation of the interfacial force invoked by the LiNbO3 coating layer, as verified by X-ray absorption spectroscopy and extended X-ray absorption near-edge structure spectroscopy. Meanwhile, the stabilities of the crystal structure are remarkably strengthened by the strong Nb–O bond activated by Nb5+ doping that is confirmed by Rietveld refinement of X-ray diffraction and differential capacitance curves. Chemically, the interface shielding effect is conducive to protecting the electrode against electrolyte corrosion along with subsequent transition-metal dissolution, ultimately rendering a faster/highly convertible lithium-ion diffusion. Greatly, the excellent electrochemical properties (74% capacity retention after 300 cycles at 2 C within 2.5–4.3 V) and structural stability (the morphology remains intact after 500 cycles at 5 C within 2.5–4.3 V) are successfully achieved. Given this, this elaborate work might inaugurate a potential avenue for rationally tuning the structure/interface evolution toward Ni-rich materials.
Rong Xudong,Li Yue,Chen Xiaofeng,Zhang Xiang,Zhao Dongdong,He Chunnian,Zhao Naiqin
Incorporating reinforcements can improve the mechanical properties of Al matrix composites but make them susceptible to corrosion attacks by facilitating the formation of a galvanic cell network along the interface. The optimization of the interfacial structure improves the corrosion resistance of the composites. Herein, a solid-state thermite reaction integrated with a heat treatment strategy was developed to create plain interfaces, encompassing the grain boundary (GB) and reinforcement–matrix interface, in an Al–CuO composite system. The intergranular corrosion behavior and susceptibility to stress corrosion cracking of the composite were comprehensively examined by immersion/electrochemical corrosion tests and microstructural characterizations. The intragranular distribution of nanosized secondary phases, i.e., Al 2 O 3 and precipitates, was investigated to address their contribution to the continuous galvanic cell detachment along the GBs and interruption of the corrosion path, thus boosting the corrosion duration. In addition, the tightly bonded Al 2 O 3 –Al interface with low strain energy distinctly lowers local susceptibility to corrosion. This study illuminates the correlation between interface characteristics and corrosion mechanisms in the composites, which can shed light on the development of high-corrosion-resistant composites.
Excessive P content (≥ 10 wt%) easily leads to cracks on the surface of electrodeposited Ni P coatings, causing rapid deterioration of corrosion performance. This study uses picosecond laser remelting (LR) technology to close cracks and improve corrosion performance. The influence of the laser parameters on the quality of laser-remelted (LRed) coatings in ambient air is discussed in detail, and the corrosion performance is evaluated through electrochemical corrosion tests. The results indicated that the scanning rate, laser power, and repetition frequency significantly affect the degree of crack closure and LRed defects. For cracks of similar sizes, both multiple-LR with a lower power (10.4 W, five times) and single-LR with a higher power (19.2 W, once) achieved an excellent crack closure. After single-LR, the surface roughness increased from 3.9 ± 0.3 nm to 33.4 ± 3.2 nm. In addition, the LRed layer crystallized from the initial amorphous state. Although the energy-dispersive spectroscopy results indicated that the oxidation behavior during the LR process was insignificant, X-ray photoelectron spectroscopy showed that the surface composition evolved from Ni/Ni–P compounds to Ni–POx after LR. Electrochemical corrosion tests indicated that the corrosion current density decreased approximately three times from 9.19 × 10 −6 to 2.91 × 10 −6 A/cm 2 after LR. Moreover, the corrosion mechanism shifted from the original stress corrosion to pitting corrosion . Thus, the LR technology can effectively improve the corrosion performance and reduce the issues caused by cracks.
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