Dielectric ceramics, as core materials for energy storage capacitors, have been widely utilized across various fields owing to their high-power density and ultrafast charge‒discharge characteristics. In this study, a synergistic strategy combining high-entropy and bandgap engineering was employed to successfully prepare lead-free high-entropy dielectric ceramics with a tungsten bronze structure having the chemical composition Ba_2.38Sr_2.12Sm_0.5Gd_0.5Ti₁Zr₁Nb_8−xTa_xO₃₀ (Ta_x, x = 0, 0.5, 1, and 1.5). The long-range ferroelectric order is effectively disrupted through high-entropy design, which enhances cationic disorder and thereby promotes relaxor ferroelectric behavior. Meanwhile, the synergistic effects of grain refinement, increased activation energy for electrical conductivity, and an enlarged bandgap significantly enhance the material’s breakdown strength. Through the collective effects of these mechanisms, the energy storage performance of the ceramics is significantly enhanced, with a recoverable energy density of 7.93 J·cm⁻³ and an energy efficiency of 94.25% achieved at x = 0.5. Furthermore, the material demonstrates a current density of approximately 971.34 A·cm⁻², a power density of 155.41 MW·cm⁻³, an ultrafast discharge time of 1.56 µs, and a discharge energy density of 5.20 J·cm⁻³. This study presents an effective approach for developing high-performance dielectric ceramic materials, highlighting their promising potential for application in advanced pulsed power systems.

To explore recycling solutions for used lithium-ion batteries (LIBs), a tribocatalytic method is proposed in this paper. When ZnO nanoparticles were used as catalysts, the leaching rates of lithium and cobalt in lithium cobaltate batteries reached 95% and 84%, respectively. In Li–Co–Mn–Ni batteries, the leaching rates of lithium, cobalt, manganese, and nickel were 96.61%, 90.00%, 76.06%, and 61.78%, respectively. In the acid leaching system, the lowest unoccupied molecular orbital (LUMO) and the highest occupied molecular orbital (HOMO) of citric acid (CA) were in more appropriate positions, indicating that CA is more prone to redox reactions when rubbed on the surface of zinc oxide. Compared with H₂O, CA is more electrostatically polarized and can participate in more reactions through electron transfer on the ZnO surface. First-principles calculations of the adsorption energies show that the interactions are stronger when CA molecules are located on the lithium cobalt oxide (LCO)(110) surface. The combination of theoretical calculations and experiments verified that the tribocatalytic weak acid leaching process is an effective ion leaching scheme. The free radicals generated during the catalytic process promoted the leaching of metal ions, thus enabling the recycling of cathode materials for lithium-ion batteries. In addition, this method has great potential for the reduction and leaching of ions.

The rapid development of capacitors with high energy density and efficiency has been driven by advanced electronic systems and innovative pulsed power applications. In this study, we prepared Sr_4.5−xBa_xSm_0.5Zr_0.5Nb_9.5O₃₀ (x = 2.5, 3, 3.5, 4, 4.5) dielectric ceramics, which exhibited structural distortion due to the co-occupation of Ba²⁺, Sr²⁺, and Sm³⁺ in the A-site and the partial substitution of Nb⁵⁺ by Zr⁴⁺ in the B-site. The ordered/disordered distribution due to these distortions thus generated polar nanoregions (PNRs) and induced a relaxation ferroelectric behavior, which was verified by the high-resolution transmission electron microscopy. Through the use of the Vogel–Fulcher and Maxwell–Boltzmann equations, we found that easy inversion and small dipole sizes are crucial for achieving high energy storage density and efficiency. The Sr_4.5−xBa_xSm_0.5Zr_0.5Nb_9.5O₃₀ (x = 3.5) dielectric ceramic displayed a ferroelectric/paraelectric transition near room temperature. Subsequent ferroelectric testing revealed large energy storage density (W_rec = 4.31 J·cm⁻³) and high efficiency (η = 93.8%) at 310 kV·cm⁻¹. Furthermore, Sr_4.5−xBa_xSm_0.5Zr_0.5Nb_9.5O₃₀ (x = 4.5) exhibited higher breakdown field strength due to its large resistivity and small grain size. This led to energy storage density of approximately 5.3 J·cm⁻³ at 460 kV·cm⁻¹. Additionally, Sr_4.5−xBa_xSm_0.5Zr_0.5Nb_9.5O₃₀ (x = 3.5) demonstrated current density (C_D) of approximately 713.38 A·cm⁻² and power density (P_D) of approximately 87.51 MW·cm⁻³, with ultrafast discharge time of 34 ns and excellent discharge energy density (W_dis) of approximately 2.27 J·cm⁻³. Overall, this study presents a promising approach for developing dielectric ceramic materials that hold potential for applications in innovative pulsed power components.