MXene is a promising electrode material for supercapacitors due to its excellent conductivity, but its self-stacking impedes ion and electron transport. To address this issue, carbon nanotubes (CNTs) were introduced as conductive spacers, and NiCo-layered double hydroxides (LDH) was rapidly deposited via an assisted liquid-phase plasma electrolysis method to construct a stable heterostructure. This design effectively alleviates ion/electron transport resistance, improves charge transfer efficiency, and mitigates the volume expansion of NiCo-LDH during cycling. Density functional theory analysis reveals enhanced electronic conductivity and ion migration at the MXene/CNT/NiCo-LDH heterointerface. Benefiting from the synergistic structure, the electrode achieves a high specific capacitance of 2145 F·g⁻¹ and maintains 95.2% of its initial capacitance after 5000 cycles. The assembled asymmetric supercapacitor delivers an energy density of 41.9 Wh·kg⁻¹ at 425.1 W·kg⁻¹ and retains 91% of capacitance after 5000 cycles. Moreover, the flexible device exhibits remarkable stability under multiple bending angles without distortion of cyclic voltammetry (CV) curves.

The design of microstructures is essential for tailoring the microwave dielectric properties of ceramics, yet the structure–property relationships in tetragonal scheelite-structured ceramics remain insufficiently understood. In this study, first-principles calculations combined with experiments were used to systematically investigate the interrelations among the sintering behavior, crystal structure, electrical characteristics, bond characteristics, and dielectric performance of NaSrLnMo₃O₁₂ (Ln = Ce, Pr, Eu, Y, and Yb) ceramics. All the compositions crystallized into a tetragonal scheelite structure (space group I4₁/a) and exhibited favorable dielectric properties with optimal sintering temperatures of 775–925 °C, ε_r = 9.8–10.34, Q×f = 30,487–69,445 GHz, and τ_f = −20.55–(−44.24) ppm/°C. The increase in ε_r originated mainly from the increased ionicity of the Na/Sr/Ln–O bonds, whereas the increase in Q×f was attributed to the increased lattice energy of the Mo–O bonds, increased bond valence, and reduced ionic/electricity disorder. The negative shift in τ_f was primarily linked to the increased linear thermal expansion coefficient α_L of the Na/Sr/Ln–O bonds. Furthermore, the electrical characteristics and relaxation mechanisms were examined, and the dielectric response in the terahertz range was confirmed. Finally, NaSrCeMo₃O₁₂ was employed to design and fabricate two antenna devices, verifying its potential for high-frequency communication. This work provides a systematic understanding of the role of Ln in optimizing the dielectric properties of tetragonal scheelite ceramics and clarifies the microscopic mechanisms underlying their performance.