Environmental Chemistry•2026•DOI: 10.7524/j.issn.0254-6108.2025040102
Calcium peroxide (CaO2) with a rich porous structure was synthesized via chemical precipitation for efficient fluoride removal from aqueous solutions. The adsorbent was characterized by SEM, BET, LPSA, and XRD, revealing a mesoporous material with a total pore volume of 0.51 cm3·g−1. Batch experiments investigated the effects of adsorbent dosage, initial fluoride concentration, reaction time, pH, and coexisting anions. Adsorption kinetics followed a fractal-like pseudo-first-order model, with intraparticle diffusion as the rate-limiting step. Equilibrium data were well described by the Sips isotherm, predicting a maximum adsorption capacity of 479.8 mg·g−1. Site energy distribution analysis indicated a normal distribution with an average energy of 13.36 kJ·mol−1. Mechanistic studies using FTIR and XPS revealed that fluoride removal proceeds via surface precipitation, ligand exchange, and electrostatic attraction. The high density of active sites contributes to the exceptional defluoridation performance, positioning CaO2 as a promising adsorbent for fluoride-contaminated water treatment.
SCIENCE CHINA Materials•2026•DOI: 10.1007/s40843-025-4079-4
Utilization of ultrahigh-nickel LiNi_xCo_yMn_1-x-yO_2 (NCM) (x > 0.97) in Li-ion batteries can distinctively boost energy density through enhanced discharge capacity. However, capacity and thermal stability deteriorate as Ni content approaches the limit. Here, we propose a facile strategy by introducing high-valence tungsten (W) into ultrahigh-nickel polycrystalline LiNi_0.98Co_0.01Mn_0.01O_2 (PCNCM98). W-doped PCNCM98 (W-PCNCM98) exhibits refined, compactly stacked primary particles, whereas PCNCM98 shows equiaxial, non-uniform larger particles. The refined microstructure enhances mechanical strength: average particle hardness of W-PCNCM98 is 104 MPa, 1.5 times higher than PCNCM98 (68 MPa). This improved mechanical property suppresses lattice volume changes and relieves microcrack formation from H2–H3 phase transition. Consequently, cycling performance in pouch-type full cells is significantly enhanced, with capacity retention of 73% after 2000 cycles at 1 C and 25 °C, 54% higher than PCNCM98. Enhanced structural stability and strong electron affinity of W6+ also improve thermal stability: exothermic peak for W-PCNCM98 is postponed to 203 °C with heat generation of 1287 J g−1, versus 190 °C and 1528 J g−1 for PCNCM98. This high-valent doping strategy stabilizes ultrahigh-nickel NCM cathodes, accelerating large-scale EV applications.
SCIENCE CHINA Materials•2026•DOI: 10.1007/s40843-026-4123-0
Aqueous aluminum-ion batteries (AAIBs) are promising for large-scale energy storage due to safety, sustainability, and theoretical high capacity. However, sluggish electron/ion transport in conventional cathodes limits rate capability. Here, we first propose high-entropy engineering of metal oxides (HEOs) as cathodes in AAIBs, leveraging the 'cocktail effect' and abundant electron transport pathways to enhance rate-capacity. Atomic-level interactions between different metal atoms broaden the d-band with reduced electronic level degeneracy, facilitating rapid electron transport, achieving one of the best rate capabilities (119.4 mAh g−1 at 10.0 A g−1) among metal-oxide cathodes. The disordered layered oxides formed with a high-entropy framework alleviate electrostatic repulsion between aluminum ions and the fixed lattice, mitigating structural degradation and imparting excellent cycling stability (over 95.1 mAh g−1 after 500 cycles at 2.0 A g−1). The optimized HEO-Cr cathode (Fe0.6Co0.6Ni0.6Mn0.6Cr0.6O4) exhibits outstanding rate performance and cycling stability. DFT simulations and electrochemical tests reveal that multi-transition metal incorporation, bandgap narrowing, and unique lattice structure drastically enhance electron transport efficiency. The layered phase formed after cycling, based on a high-entropy framework, overcomes challenges from high charge density aluminum ions, significantly enhancing cycling stability. This work paves the way for high-performance AAIBs and other aqueous multivalent metal ion batteries by rationally designing high-entropy engineering.