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With the rise of flexible electronics, flexible rechargeable batteries have attracted widespread attention as a promising power source in new generation flexible electronic devices. In this work, $\alpha$-Fe₂O₃ nanorods grown on carbon cloth have been synthesized through a facile hydrothermal method as binder-free electrode material. The electrochemical performance measurements show that $\alpha$-Fe₂O₃ nanorods possess high specific capacitance and specific capacity retention of 119% after 100 cycles. The combination of low-cost and excellent electrochemical performance makes $\alpha$-Fe₂O₃ nanorods promising anode materials for sodium-ion batteries.

Owing to their high ionic conductivity and excellent flexibility, composite polymer electrolytes (CPEs) have been widely studied in solid lithium metal batteries (SLMBs). In this study, a new solid electrolyte of NASICON-type Li₃Zr₂Si₂${\text{PO}}_{12}$ (LZSP) was prepared by the sol–gel method, and then a new type of CPE membrane containing LZSP and Poly(vinylidene fluoride) (PVDF) was synthesized by slurry-casting method. The CPE membrane presented much higher ionic conductivity of 5.66 × 10${}^{-5}$ S ⋅ cm${}^{-1}$ at 25^∘C and stronger electrochemical stability compared to the one without LZSP. In addition, the cells containing the composite electrolyte membrane exhibited considerable rate performance and cycle performance.

Nickel-rich LiNi${}_{0.8}$Co${}_{0.1}$Mn${}_{0.1}$O₂ (NCM811) oxide is a prospective cathode material of Li-ion batteries owing to its high energy density and affordable price, however, it suffers from the poor cycling performance. The doping for metal cations is considered as an effective way to enhance its cycling stability. In this work, titanium was chosen to partially substitute transition-metal ions, i.e. Ni, Co and Mn, and the Ti content was optimized to improve the electrochemical performance of NCM811. The Ti-doped Li(Ni${}_{0.8}$Co${}_{0.1}$Mn${}_{0.1}{){}_{1-x}}_{}$Ti${}_x$O₂ powder was prepared using high temperature solid-state synthesis. The layered $\alpha$-NaFeO₂-type structure of NCM811 survives in the doped samples, and the lattice parameters $a$ and $c$ increase linearly with the Ti content. XPS spectra indicate that the Ni ions show a mixing state of +2 and +3, and the portion of Ni${}^{2+}$ increases by the Ti doping. The cycling stability is improved evidently by a small amount of Ti doping, i.e. capacity retention of 88.3–96.9% for $x$ = 0.01–0.03 versus 64.1% for $x$ = 0 after 100 cycles at 0.1 C. Thus, the sample with $x$ = 0.01 delivers the high discharge capacity of 180.6 mAh g${}^{-1}$ after 100 cycles, much greater than 116.5 mAh g${}^{-1}$ of $x$ = 0. Nevertheless, more Ti doping with $x$ = 0.04–0.05 deteriorates the electrochemical performance. It illustrates the presence of optimal Ti-doping range in NCM811, which was rationalized as the synergetic effects of bond strength, Li${}^{+}$ diffusion, chemical composition and valence state of cations.

Refrigeration, air conditioning and heat pump equipments (generally known as heat pumps) are very important for the civilized society. However, discharged refrigerants from heat pumps and exhausted carbon dioxide to drive heat pumps result in serious environmental problems. For this reason, fluorocarbon refrigerants are limited or regulated. To alleviate the problems, new refrigerants with lower GWP and higher cycle performance must be developed and used. In this paper, calculated thermophysical properties of hydrofluoroolefin refrigerants using databases are evaluated with experimental data. Then, the fundamental cycle performance of air conditioning by using major refrigerants is studied based on their thermophysical properties. The results show that there is no adequate refrigerant for air conditioning applications. Heat pumps with new refrigerants including refrigerant mixtures must be developed as fast as possible. It leads to that HFC refrigerants must be used taking care until the new refrigerants will be available.

With the rise of flexible electronics, flexible rechargeable batteries have attracted widespread attention as a promising power source in new generation flexible electronic devices. In this work, α-Fe₂O₃ nanorods grown on carbon cloth have been synthesized through a facile hydrothermal method as binder-free electrode material. The electrochemical performance measurements show that α-Fe₂O₃3 nanorods possess high specific capacitance and specific capacity retention of 119% after 100 cycles. The combination of low cost and excellent electrochemical performance makes α-Fe₂O₃ nanorods promising anode materials for sodium-ion batteries.

The effect of Fe addition on the cycle performance of FeS₂cathode for Li/FeS₂cell was investigated. After cathode fabrication, additional compounds were not formed. In the case of Li/FeS₂ cell without Fe, a large voltage drop was observed at initial discharge process. Also, the cell showed poor cycle performance until the 40th cycle. On the other hand, the Li/FeS₂ cell with 10wt.% Fe delivered a higher the 1st discharge capacity of about 670mAh/g-FeS₂ and it exhibited better cycle performance than the cell without Fe. Moreover, rate capability of the cell was improved by the addition of Fe in the FeS₂cathode.