AgBi 3 S 5 is a promising n-type thermoelectric material with low lattice thermal conductivity. In this paper, polycrystalline bulk samples of n-type Ag 1− x Sb x Bi 3 S 5 ( x = 0–0.03) were prepared by high-temperature reaction and pressed by spark plasma sintering (SPS). Electrical conductivity of AgBi 3 S 5 is enhanced significantly due to the increased carrier concentration. There is a remarkable enhancement of power factor from ~ 2.1 μW·cm −1 ·K −2 for undoped AgBi 3 S 5 to ~ 3.3 μW·cm −1 ·K −2 for Ag 0.97 Sb 0.03 Bi 3 S 5 . The Sb lone pair electrons, as indicated from density functional theory (DFT) calculation results, contribute to the Fermi energy and enhance the carrier effective mass. In addition, the point defects enhance phonon scattering and decrease the lattice thermal conductivity. Owing to the enhanced power factor and reduced thermal conductivity, the thermoelectric figure of merit ( ZT ) at 800 K for Ag 0.97 Sb 0.03 Bi 3 S 5 reaches 0.53, which is 70% higher than that of the pristine AgBi 3 S 5 .
Nowadays, the poor conductivity and unstable structure have become obstacles for the popularization of Na3V2(PO4)3 (NVP). In the current work, a dual-modified Mn0.1Cl0.3-NVP composite doped with Mn and Cl is prepared by a facile sol–gel method. When Mn2+ with a large ionic radius replaces small V3+, it can improve the stability of the NVP crystal structure. In addition, the replacement of V3+ by Mn2+ in a low valence state can generate redundant hole carriers, which is conducive to the rapid transport of electrons. The substitution of PO43− by Cl−, which is more electronegative, can reduce the impedance and facilitate the movement of Na+. Owing to the synergistic effect of Mn and Cl co-substitution, the structural stability of NVP was systematically enhanced, and the electron transfer and ion diffusion were effectively improved. Consequently, the optimized Mn0.1Cl0.3-NVP sample demonstrated superior electrochemical performance and kinetic properties. It exhibited a high reversible capacity of 109.2 mA h g−1 at 0.1C. Even at 15 and 30C, high discharge capacities of 70.3 mA h g−1 and 68.2 mA h g−1 were observed after 2000 cycles with capacity retention above 80%. Moreover, it delivered remarkable capacities of 77.1 and 73.4 mA h g−1 at 100 and 200C with retained capacity values of 50.3 and 47 mA h g−1, respectively, after 2000 cycles. Furthermore, the assembled Mn0.1Cl0.3-NVP//HC full cell delivered a high value of 94.7 mA h g−1 and lit LED bulbs, indicating its excellent application potential.
危险品化学品经营许可证（带存储）