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HZ
Verified CAS / Academic Author2 Decoded Studies

Prof. Hankuo Zhang

Guizhou University

Co-Affiliations:School of Resources and Safety Engineering, Central South University, Changsha 410083, China

Research Publications & English Decoded Briefs

Showing 2 publications
Transactions of Nonferrous Metals Society of China (中国有色金属学报)2026DOI: 10.1016/S1003-6326(26)67065-3

Single Crystal NCM811 Cathode Material Prepared by Rapid Solvothermal Method

Polycrystalline LiNi0.8Co0.1Mn0.1O2 (NCM811) cathodes undergo intergranular cracking and structural collapse during extended cycling, limiting their commercial viability. This study reports single-crystalline NCM811 synthesized via a rapid ethanol–water solvothermal method. The solvothermal duration was varied, and the 60 min sample (NCM-60) exhibited optimal electrochemical performance. X-ray diffractometry confirmed an α-NaFeO2 structure with R-3m space group and high crystallinity. NCM-60 delivered a reversible capacity of 157.28 mA·h/g at 1C and a capacity retention of 55.06% after 200 cycles, significantly outperforming polycrystalline NCM (PC-NCM). Cross-sectional scanning electron microscopy revealed no apparent cracks in NCM-60 after 200 cycles, whereas PC-NCM exhibited severe intergranular fracture. The results demonstrate that shortening solvothermal time reduces precursor particle size and crystallinity, but 60 min yields the best balance. Pre-oxidation of the carbonate precursor before lithiation is recommended to mitigate CO2 evolution and lithium–nickel disorder during high-temperature sintering. This rapid solvothermal route offers a scalable pathway to single-crystal NCM811 with enhanced cycling stability and mechanical integrity.

Int. Journal of Mining Science and Technology (采矿与安全工程)2025DOI: 10.1016/j.ijmst.2025.12.012

Effects of Combined Dynamic-Static Loading and Acidic Corrosion Treatment on the Mechanical Properties and Microstructure of Shale

A critical scientific gap exists in quantifying the intrinsic mechanisms of shale mechanical property degradation induced by the combined effects of perforation (impact) and acidization—two core techniques for shale reservoir permeability enhancement. To address this gap, this study proposed an innovative coupled experimental framework integrating dynamic-static cyclic loading (to simulate perforation impact) and acid erosion. Static uniaxial compression tests were performed on treated damaged shale samples, with microstructural characterization via X-ray diffraction (XRD) and scanning electron microscopy (SEM). Key findings include: (1) The damage factor (characterized by longitudinal wave velocity) showed a significant positive correlation with acid concentration; (2) Combined damage (impact + acidization) caused far more severe mechanical deterioration than single damage modes—for instance, samples under combined damage with 20% hydrochloric acid exhibited a strength reduction to 158.97 MPa, with sharp decreases in peak strength and elastic modulus; (3) Damage reduced total energy and elastic strain energy of samples while increasing dissipated energy proportion, leading to more developed internal fractures and severe failure in combined damage samples; (4) Acidization promoted sample fragmentation into smaller debris, resulting in significantly higher fractal dimensions of acidized shale than other damage types under the same acid concentration; (5) XRD and SEM analyses confirmed that high-concentration acid erosion reduced shale carbonate content, and the synergy of mechanical pre-damage and chemical dissolution in combined damage accelerated acid-rock reactions, significantly increasing micro-interfacial pores and degrading shale structural integrity. This study’s innovation lies in establishing a coupled experimental framework that reproduces the actual “perforation-acidization” sequence, quantitatively revealing the synergistic degradation mechanism of shale mechanical properties under combined damage—providing a novel theoretical basis for optimizing shale reservoir stimulation parameters.