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Relaxor [(Bi 1/2 Na 1/2) 0.94 Ba 0.06 ] (1-1.5x) La x TiO 3 (x = 0, 0.03, 0.06, 0.09) ceramics (La-doped BNT-6BT hereafter) with composition close to the morphotropic phase boundary (MPB) were successfully prepared by using the conventional solid state reaction method. All samples present almost a pure perovskite phase with coexistence of tetragonal and rhombohedral. With the increase of La doping content, the degree of the dielectric relaxor dispersion around the dielectric peak which is close to the room temperature increases, and also the transition temperature of ferroelectric-to-relaxor (T F-R) shifts 120K towards a lower temperature at x=0.09. The maximum value of the temperature change (ΔT) of the electrocaloric (EC) effect decreases sharply from 1.1 K at x = 0 to 0.064 K at x = 0.09. A large positive EC effect (maximum ΔT ~ 0.44 K) in a broad temperature range (~ 90 K) close to room temperature is achieved at x = 0.03, indicating that it is a promising lead-free material for application in solid state cooling system. Moreover, it is found that the Maxwell relationship can be well used to assess the EC effects of the La-doped BNT-6BT

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Applications of dynamic membrane (DM) filtration and factors affecting formation, filtration, and cleaning are introduced. DMs have been studied extensively for wastewater treatment in recent years. DM formation methods and mechanisms are explained. Effects of supporting material, deposited material, formation pressure, and pH on the DM formation are discussed in detail. The impacts of operation pressure, aeration intensity, cross-flow velocity, temperature, and other parameters on the DM filtration process are evaluated and different DM cleaning strategies are reviewed. The applications of DMs to treatments of municipal wastewater, surface water, oily water, industrial wastewater, sludge, and microalgae harvesting are discussed. Finally, possible future research directions and some guidelines for DM technology are given.

A promising lithium salt of Li difluorophosphate (LiPO2F2) is introduced and added to the basic electrolyte (1 M LiPF6 + dimethyl carbonate (DMC)/ethyl methyl carbonate (EMC)/propylene carbonate (PC)/fluoroethylene carbonate (FEC)) to enhance the electrochemical performance of lithium-ion batteries by changing its concentration at low temperatures. Experiments show that LiPO2F2 can obviously improve the electrolyte’s ionic conductivity, especially. Compared with the baseline (6.29, 5.14, 4.62, 3.77, and 3.15 mS cm–1) under the same conditions, the ionic conductivities of the 2 wt % LiPO2F2-containing electrolyte (2 LiPO2F2) are 7.18, 5.32, 5.23, 4.04, and 3.57 mS cm–1. From this, it is clear that the integrated low-temperature electrochemical performances have been significantly improved. The specific discharge capacities of the 2 wt % LiPO2F2-added electrolyte at 0.2C are 161.4, 157.2, 148.9, and 137.5 mAh g–1 in the range from 25 to −40 °C, which are significantly much higher compared with the basic electrolyte (145.3, 149.4, 135.1, and 107.0 mAh g–1, respectively). Additionally, the addition of LiPO2F2 can promote profoundly the composition and morphology characteristics of the cathode–electrolyte interface (CEI) film; namely, it is a uneven lithium alkyl carboxylate before the addition of LiPO2F2; after that, it becomes an even LiF film, and meanwhile, the new film will facilitate Li+ transport in the electrolyte, further boosting the eletrochemical performance of the cells under low temperatures. At −40 °C under the same current density, the specific discharge capacity is 81.97 mAh g–1 after 50 cycles, while at the same temperature, the specific discharge capacity of the basic electrolyte battery is only 33.37 mAh g–1; that is, the discharge capacity has a staggering 145.6% improvement at −40 °C. In conclusion, the lithium-ion batteries containing LiPO2F2 may meet the application requirements of ultra-low-temperature conditions.