Thermal batteries are solid-state, thermally activated batteries with long storage times and high reliability. FeS2 is used as a cathode material commonly, but the high internal resistance and low voltage platform limit the improvement of battery performance. Herein, the 1T-phase vanadium disulfide (VS2) is prepared via the scalable hydrothermal method and applied to thermal battery cathode materials for the first time. 1T-VS2 lamellar flower clusters have high electronic conductivity (1.583 S cm–1) at room temperature, which is 75 times higher than FeS2 (0.021 S cm–1). Mechanism analysis shows that 1T-VS2@V2O3 can be formed based on the part of 1T-VS2 being oxidized to V2O3 at the discharge temperature. Benefiting from the synergistic effect of vanadium sulfide and vanadium oxide as a cathode for thermal batteries enhanced specific capacity (292.4 mA h g–1) and mass energy density (572.5 W h kg–1) when cutoff voltage is 1 V. Additionally, the discharge results indicate that the cells utilizing 1T-VS2 cathodes provided a higher voltage platform of 2.11 V than 1.84 V for FeS2. This impressive work can offer a good strategy for boosting cathode materials for a high-performance thermal battery.
Li–O 2 batteries have received considerable attention owing to their high theoretical gravimetric energy densities. However, the sluggish kinetic barrier between gaseous O 2 and solid products leads to severe polarized overpotenial. Besides, the gas-open cell architecture and cumbrous O 2 storage accessories bring additional burdens on practical application. Here, by pre-embedding Li 2 O nanoparticles into an iridium–graphene catalytic host, we confine the O 2 -free reversible Li 2 O/Li 2 O 2 interconversion within a sealed cell environment. After rationally controlling the depth of charge, the O 2 /superoxo-free charge capacity can be extended to 400 mAh g –1 (based on the entire cathodic loading mass), with only 0.12 V round-trip overpotential. Ultrastable rechargeability can be achieved for over 2,000 cycles with 99.5% coulombic efficiency. Moreover, matched with a silicon anode, the full-cell output gravimetric energy density can reach nearly 600 Wh kg –1 (based on the loading mass of both electrodes). This work shows that reversible oxide–peroxide conversion can be utilized for the development of high-energy-density sealed battery technologies.
Spin regulation of active sites is sparking much interest in boosting oxygen electrocatalytic performance. However, in amorphous electrocatalysts, the design principle of spin regulation to promote catalytic activity remains unclear. Herein, we synthesized a series of heteroatom-doped amorphous transition metal sulfides with regulated spin states using a one-step hydrothermal process. Especially in Mo-doped CoS, the spin state of Co 2+ was successfully modulated to the low-spin state, which could optimize the adsorption free energy of various intermediates, improving the oxygen reduction reaction kinetics. The fabricated Zn-air batteries (ZABs) delivered good cycle stability (over 100 h). The large ZAB (100 cm 2 ) exhibited a high discharge voltage (1.25 V under 0.5 A) and a superior overall mass-energy density (93 W h kg −1 ), which illuminated a 2.5-m light-emitting-diode ribbon for over seven days. This work provides new insight into the mechanism of engineering spin states in amorphous materials for oxygen electrocatalysis.
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