Bifunctional flame retardant solid-state electrolyte toward safe Li metal batteries

Solid polymer electrolytes(SPEs)are one of the most promising alternatives to flammable liquid electrolytes for building safe Li metal batteries.Nevertheless,the poor ionic conductivity at room temperature(RT)and low resistance to Li dendrites seriously hinder the commercialization of SPEs.Herein,we design a bifunctional flame retardant SPE by combining hydroxyapatite(HAP)nanomaterials with Nmethyl pyrrolidone(NMP)in the PVDF-HFP matrix.The addition of HAP generates a hydrogen bond network with the PVDF-HFP matrix and cooperates with NMP to facilitate the dissociation of Li TFSI in the PVDF-HFP matrix.Consequently,the prepared SPE demonstrates superior ionic conductivity at RT,excellent fireproof properties,and strong resistance to Li dendrites.The assembled Li symmetric cell with prepared SPE exhibits a stable cycling performance of over 1200 h at 0.2 m A cm^(-2),and the solid-state LiFePO_4||Li cell shows excellent capacity retention of 85.3%over 600 cycles at 0.5 C.

Experimental research on refractory performance of reinforced concrete beams strengthened with CFRP sheets bonded with an inorganic adhesive

To meet the requirement of fire endurance for concrete structures strengthened with CFRP sheets, this study develops an inorganic adhesive whose strength at 600 ℃ is not lower than that at normal room temperature. The inorganic adhesive is then used to bond CFRP sheets on reinforced concrete beams in order to strengthen them. The fire protection of the CFRP sheets is done using the thick-type fireproofing coatings for tunnel ( TFCT) and steel structure ( TFCSS) respectively. Four specimens are tested in the furnace together. Specimens are exposed to fire for 1. 5 h in according to the ISO834 standard fire curve,and then naturally cooled for 1 h. In the tests,the largest displacements at the mid-span positions of specimens are only from 1 /1400 to 1 /318 of actual span corresponding to the highest temperatures from 300 ℃ to 470 ℃. After the specimens are naturally cooled to the normal temperature and the fireproofing coatings are then removed,it can be seen that the CFRP sheets keep in a good state,which indicates that CFRP sheets can be tightly bonded on the concrete and work well together with the concrete beams during and after fire. Besides,the tests also verify that the fire performance of TFCT is superior to TFCSS for the strengthened beams.

Electrolyte chemistry for lithium metal batteries

Li metal batteries(LMBs) are considered as the next-generation energy storage systems because of their high energy density.However,due to the high reactivity of Li metal with the electrolyte,the unwanted safety concerns inhibit the practical application of LMBs.To overcome these drawbacks,exploring suitable electrolytes is considered to be urgent.Great effort has been made to modify electrolytes to achieve the stability of LMBs.In this review,different kinds of LMBs are firstly introduced.Then,the regulation of electrode–electrolyte interphase is discussed.Next,recent advances on the functional electrolytes for LMBs are overviewed,including fireproof electrolytes,extreme-temperature electrolytes and high-voltage electrolytes.Finally,the perspective on the development of future electrolytes is provided.

Theoretical Study on Efficiency of Anti-explosion and Fireproof Agents

Multi-protection is a principle in security management, and the use of anti-explosion and fireproof agents is a crucial part of it. In this paper, the properties of nano-oxide particles in the field of anti-explosion and fireproof were analyzed. The sedimentation velocity of nanometer particles was calculated. CH4 was taken as an example, and its combustion mechanism of the initial stages was concluded. The effects of 15 oxides on molecular energies of the reaction system were calculated with program Hyperchem 6, and the possible contact manner between radi- cals and oxides was got. It was concluded that oxides, such as ZrO2, could combine with radicals, and thus prevent the combustion reaction. It was found that the nano-ZrO2 eruptively generated aerosol is superior to other counterparts in serving as the anti-explosion and fireproof agent, and therefore, will play an increasingly important role in the security management.