Strong internal electric field enhanced polysulfide trapping and ameliorates redox kinetics for lithium-sulfur battery

The shuttle effect of polysulfides is a major challenge for the commercialization of lithium-sulfur battery.The systematic modification of separators has the potential to solve these problems by enhancing the adsorption and catalytic conversion of polysulfides.Herein,strong internal electric field bismuth oxycarbonate(Bi_(2)O_(2)CO_(3))nanoflowers decorated conductive carbon(DC+BOC)is proposed to be systematically modified on separator.This intermediate layer not only possesses a strong affinity for polysulfides,but also promotes the conversion of polysulfides and induces the formation of a stable solid electrolyte interphase(SEI)layer,thereby improving the rate performance and cycling stability of the battery.As expected,the modified membrane achieved a high specific capacity of 713 mA h g^(-1) at 5 C.At 1 C,high reversibility of 719 mA h g^(-1) was achieved after 550 cycles with only 0.044%decay per cycle.More importantly,under the sulfur loading of 5.1 mg cm^(-2),the area specific capacity remained at4.1 mA h cm^(-2) after 200 cycles,and the attenuation rate per cycle was only 0,056%.This work provides a new strategy to overcome the shuttle effect of polysulfide,and shows great potential in the application of high-performance lithium-sulfur batteries.

Regulating f orbital of Tb electronic reservoir to activate stepwise and dual-directional sulfur conversion reaction

The sluggish kinetics in multistep sulfur redox reaction with different energy requirements for each step,is considered as the crucial handicap of lithium–sulfur(Li–S)batteries.Designing an electron reservoir,which can dynamically release electron to/accept electron from sulfur species during dis-charge/charge,is the ideal strategy for realizing stepwise and dual-directional polysulfide electrocatalysis.Herein,a single Tb^(3+/4+)oxide with moderate unfilled f orbital is synthetized as an electron reservoir to optimize polysulfide adsorption via Tb–S and N…Li bonds,reduce activation energy barrier,expe-dite electron/Li+transport,and selectively catalyze both long-chain and short-chain polysulfide conversions during charge and discharge.As a result,Tb electron reservoir enables stable operation of low-capacity decay(0.087%over 500 cycles at 1 C),high sulfur loading(5.2 mg cm^(2))and electrolyte-starved(7.5μL mg^(-1))Li–S batteries.This work could unlock the potential of f orbital engineering for high-energy battery systems.

Solvent-mediated handedness inversed and amplified circularly polarized luminescence system based on camptothecin derivative

To realize the handedness controllable circularly polarized luminescence(CPL) system remains challenging. Herein, the solvent-mediated CPL inversion and amplification systems were successfully constructed by camptothecin derivative(CPT-A). Due to the planar structure of N,N-dimethylformamide, it could coassemble with CPT-A, resulting in the alteration of g_(lum) from –0.0082 to +0.0085 by increasing water content. While in the non-planar solvent(hexafluoroisopropanol), the g_(lum) was amplified to 0.034 with the increase in water content. Moreover, the CPT-A could react with the glutathione, resulting in the anticancer drug CPT to make it more toxic to the cancer cells. Overall, the handedness controllable CPL systems were realized by tuning the supramolecular self-assembly of a prodrug.