Mg-based alloy anodes suffer from severe corrosion in alkaline electrolytes, which substantially impedes their cycle life and thereby limits their suitability as anode materials for nickel–metal hydride (Ni-MH) batteries. This work modifies the conventional 6 M KOH electrolyte by adding 0.1 M Al2(SO4)3·18H2O. The electrochemical hydrogen storage properties of Mg0.45Ti0.05Ni0.50alloy in this electrolyte and its microstructural evolution during cycling are studied. In the 6 M KOH + 0.1 M Al2(SO4)3·18H2O electrolyte, a protective layer consisting of Mg2Al(OH)7is formed on the surface of the Mg0.45Ti0.05Ni0.50alloy anode during charge/discharge cycling instead of Mg(OH)2, effectively preventing further corrosion and improving its cycle life. The Mg0.45Ti0.05Ni0.50alloy anode delivers a maximum discharge capacity of 479.0 mAh g−1and maintains 318.4 mAh g−1after 30 cycles in the 6 M KOH + 0.1 M Al2(SO4)3·18H2O electrolyte, which is significantly superior to that achieved in the 6 M KOH electrolyte (471.1 mAh g−1and 201.8 mAh g−1, respectively). This work provides a new strategy for improving the cycle stability of Mg-based alloy anodes.
Zhiyuan Song,Sidra Chaudhary,Zainab Bibi,Yong Wu,Qinxiang Jia,Xiaoyong Li,Yang Sun
Two hydrophilic copolymers containing functional groups such as carboxyl, amido, and sulfonic acid are synthesized using ammonium persulfate-catalyzed free radical polymerization in water. Aluminum sulfate is then introduced, resulting in two polymer complexes that exhibit reduced cement setting times (initial, 1.16–2.44 min; final, 2.02–3.14 min) and improved compressive (24 h, 5.81–7.25 MPa) and flexural (24 h, 2.80–2.99 MPa) strengths compared to pure aluminum sulfate-facilitated cementing (initial, 19.11 min; final, 37.05 min; compressive, 24 h, 5.51 MPa; flexural, 24 h, 2.56 MPa). Following this, ball-milled illite powder is added, and the resulting admixtures further display slightly prolonged setting times (initial, 2.35–2.99 vs. 1.16–2.44 min; final, 3.98–4.35 vs. 2.02–3.14 min), along with comparable compressive strengths (5.85–7.11 vs. 5.81–7.25 MPa) and enhanced flexural strengths (3.92–5.83 vs. 2.80–2.99 MPa). Notably, a unique adhesive pozzolanic clinker, Ca54MgAl2Si16O90(54CaO·MgO·Al2O3·16SiO2), emerges in the presence of illite-based admixtures, contributing to the mechanical strength development of the hydrated mortars. Although illite itself is hydrophobic, the coating of ball-milled illite powder with aluminum sulfate and copolymers facilitates its dispersion into the gaps and pores of the cement matrix during setting, thereby increasing the flexural strength. This work presents an interesting approach to utilizing illite materials in cement applications, which is significant for reducing CO2emissions during cement production and use.
Zhiyuan Song,Sidra Chaudhary,Yan Ding,Yujiao Yan,Kewei Peng,Yong Wu,Qinxiang Jia,Xiaoyong Li,Yang Sun
This study develops a series of functional admixtures for ordinary Portland cement based on a synthesized water-soluble terpolymer and its ball-milled composites with aluminum sulfate. The foundational admixture significantly accelerates cement setting, achieving an initial setting time of 4.33 min and a final setting time of 7.98 min, performance that exceeds the Chinese National Standard GB/T 35159–2017 requirements for flash-setting admixtures (which specify ≤5 min for initial setting and ≤12 min for final setting), while delivering a 24-hour compressive strength of 5.0 MPa and flexural strength of 1.6 MPa. The acceleration mechanism is attributed to the in-situ formation of the active intermediate (H 3 O)Al 3 (SO 4 ) 2 (OH) 6 . Incorporating potassium titanate whiskers—A3 derived from anatase (TiO 2 ) and A4 from metatitanic acid (TiO 2 ·H 2 O)—forms microcapsule-structured composites that further enhance performance. The A3-based composite reduces initial setting time to 3.83 min and final setting time to 7.10 min, while significantly improving mechanical strength, achieving a 24-hour compressive strength of 6.8 MPa that nearly meets the GB/T 35159–2017 standard requirement of ≥ 7.0 MPa at 24 h. A4-based whiskers provide comparable acceleration and demonstrate superior long-term flexural strength, reaching 5.1 MPa at 28 days. Mechanistic analysis reveals aluminum species drive rapid setting while whiskers enhance strength through distinctive phase transformations during hydration. Furthermore, 3-aminopropyltriethoxysilane-modified whiskers (both A3 and A4) produce admixtures that function as potent set retarders while simultaneously increasing 24-hour compressive and flexural strengths by 113 % and 91 % respectively compared to plain cement mortar, demonstrating exceptional superplasticizer characteristics. A key finding is the whisker-specific optimization strategy: silane pretreatment benefits A3 for achieving both accelerated setting and high strength, whereas unmodified A4 performs better in the same application. This work elucidates the design principles and mechanisms of tunable multifunctional cement admixtures, establishing strategic pathways for developing advanced construction materials suitable for applications ranging from shotcrete to oil well cementing.
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