Bifunctional polymer electrolyte with higher lithium-ion transference number for lithium-sulfur batteries

Lithium-sulfur(Li-S)batteries have attracted enormous interest due to their super-high theoretical energy density(2600 W·h/kg)in recent years.However,issues such as lithium dendrites and the shuttle effect severely hampered the large-scale application of Li-S batteries.Herein,a novel bifunctional gel polymer electrolyte,poly(N,Ndiallyl-N,N-dimethylammonium bis(trifluoromethylsulfonylimide))-P(VDF-HFP)(PDDA-TFSI-P(VDF-HFP),PTP),was prepared by anion exchange reaction to tackle the above problems.Benefited from the interaction between TFSI-and quaternary ammonium ion in PTP,a higher lithium-ion transference number was obtained,which could availably protect Li metal anodes.Meanwhile,due to the adsorption interactions between PDDA-TFSI and polysulfides(LiPSs),the shuttle effect of Li-S batteries could be alleviated effectively.Consequently,the Li symmetric batteries assembled with PTP cycled more than 1000 h and lithium metal anodes were protected effectively.Li-S batteries assembled with this polymer electrolyte show a discharge specific capacity of 813 mA·h/g after 200 cycles and 467 mA·h/g at 3 C,exhibiting excellent cycling stability and C-rates performance.

Characterization and prediction of tailpipe ammonia emissions from in-use China 5/6 light-duty gasoline vehicles

On-road tailpipe ammonia (NH3) emissions contribute to urban secondary organic aerosol formation and have direct or indirect adverse impacts on the environment and human health. To understand the tailpipe NH3 emission characteristics, we performed comprehensive chassis dynamometer measurements of NH3 emission from two China 5 and two China 6 light-duty gasoline vehicles (LDGVs) equipped with three-way catalytic converters (TWCs). The results showed that the distance-based emission factors (EFs) were 12.72 ± 2.68 and 3.18 ± 1.37 mg/km for China 5 and China 6 LDGVs, respectively. Upgrades in emission standards were associated with a reduction in tailpipe NH3 emission. In addition, high NH3 EFs were observed during the engine warm-up period in cold-start cases owing to the intensive emissions of incomplete combustion products and suitable catalytic temperature in the TWCs. Notably, based on the instantaneous NH3 emission rate, distinct NH3–emitting events were detected under high/extra high velocity or rapid acceleration. Furthermore, NH3 emission rates correlated well with engine speed, vehicle specific power, and modified combustion efficiency, which were more easily accessible. These strong correlations were applied to reproduce NH3 emissions from China 5/6 LDGVs. The predicted NH3 EFs under different dynamometer and real-world cycles agreed well with existing measurement and prediction results, revealing that the NH3 EFs of LDGVs in urban routes were within 8.55–11.62 mg/km. The results presented here substantially contribute to improving the NH3 emission inventory for LDGVs and predicting on-road NH3 emissions in China.