Enhanced cycle performance of Li/S battery with the reduced graphene oxide/activated carbon functional interlayer

The high-energy lithium/sulfur(Li/S) battery has become a very popular topic of research in recent years due to its high theoretical capacity of 1672 m Ah/g. However, the polysulfide shuttle effect remains of great concern with a great number of publications dedicated to its mitigation. In this contribution, a three-dimensional(3D) reduced graphene oxide/activated carbon(RGO/AC) film, synthesized by a simple hydrothermal method and convenient mechanical pressing, is sandwiched between the separator and the sulfur-based cathode, acting as a functional interlayer to capture and trap polysulfide species. Consequently, the Li/S cell with this interlayer shows an impressive initial discharge capacity of 1078 m Ah/g and a reversible capacity of 655 m Ah/g even after 100 cycles. The RGO/AC interlayer impedes the movement of polysulfide while providing unimpeded channels for lithium ion mass transfer. Therefore, the RGO/AC interlayer with a well-designed structure represents strong potential for high-performance Li/S batteries.

A porous puckered V_(2)O_(5) polymorph as new high performance cathode material for aqueous rechargeable zinc batteries

Aqueous rechargeable zinc batteries are getting increasing attention for large-scale energy storage owing to their advantages in terms of cost,environmental friendliness and safety.Here,the layered puckeredγ’-V_(2)O_(5) polymorph with a porous morphology is firstly introduced as cathode for an aqueous zinc battery system in a binary Zn^(2+)/Li^(+)electrolyte.The Zn‖γ’-V_(2)O_(5) cell delivers high capacities of 240 and190 mAh g^(-1) at current densities of 29 and 147 mA g^(-1),respectively,and remarkable cycling stability in the 1.6 V-0.7 V voltage window(97%retention after 100 cycles at 0.15 A g^(-1)).The detailed structural evolution during first discharge-charge and subsequent cycling is investigated using X-ray diffraction and Raman spectroscopy.We demonstrate a reaction mechanism based on a selective Li insertion in the1.6 V-1.0 V voltage range.It involves a reversible exchange of 0.8 Li^(+)in γ’-V_(2)O_(5) and the same structural response as the one reported in lithiated organic electrolyte.However,in the extended 1.6 V-0.7 V voltage range,this work puts forward a concomitant and gradual phase transformation from γ’-V_(2)O_(5) to zinc pyrovanadate Zn_(3)V_(2)O_(7)(OH)2.2 H_(2)O(ZVO)during cycling.Such mechanism involving the in-situ formation of ZVO,known as an efficient Zn and Li intercalation material,explains the high electrochemical performance here reported for the Zn‖γ’-V_(2)O_(5) cell.This work highlights the peculiar layered-puckeredγ’-V_(2)O_(5) polymorph outperforms the conventionalα-V_(2)O_(5) with a huge improvement of capacity of 240 mAh g^(-1)vs 80 mAh g^(-1) in the same electrolyte and voltage window.

Single Zn atoms anchored on hollow carbon nanofiber network for dendrite-free lithium metal anode of flexible Li–S full cell

The attractive energy density of lithium-sulfur(Li-S)batteries makes them desirable energy storage systems;however,the slow reaction kinetics and formation of lithium dendrites prevent them from reaching full potential.To address this issue,hierarchical porous carbon nanofibers network containing Zn single atoms(ZnSA@HPCNF)is synthesized by electrospinning and carbonization.This structure serves as the main anode body,providing excellent chemical anchoring and lipophilicity.The uniform distribution of Zn single atoms and N4coordination supports uniform deposition and continuous plating/stripping of lithium.The results show that the Li|Li/ZnSA@HPCNF symmetrical battery presents stable and low overpotential during 700-and 900-h iterative plating/stripping process at1 and 5 mA·cm^(-2),respectively.Furthermore,the S/CNT||Li/ZnSA@HPCNF full cell shows good flexibility,reversible capacity and cycling stability.This work provides a lithium host strategy based on single-atom dispersed hierarchical porous carbon network,enabling the design of rational lithium metal anodes for use in flexible Li-S full cells.

Nickel embedded porous macrocellular carbon derived from popcorn as sulfur host for high-performance lithium-sulfur batteries

Due to the demands for high performance and ecological and economical alternatives to conventional lithium-ion batteries(Li Bs),the development of lithium-sulfur(Li-S)batteries with remarkably higher theoretical capacity(1675 m A h g-1)has become one of the extensive research focus directions worldwide.However,poor conductivity of sulfur,critical cyclability problems due to shuttle of polysulfides as intermediate products of the cathodic reaction,and large volume variation of the sulfur composite cathode upon operation are the major bottlenecks impeding the implementation of the next-generation Li-S batteries.In this work,a unique three-dimensional(3D)interconnected macrocellular porous carbon(PC)architecture decorated with metal Ni nanoparticles was synthesized by a simple and facile strategy.The as-fabricated Ni/PC composite combines the merits of conducting carbon skeleton and highly adsorptive abilities of Ni,which resulted in efficient trapping of lithium polysulfides(Li PSs)and their fast conversion in the electrochemical process.Owing to these synergistic advantageous features,the composite exhibited good cycling stability(512.3 mA h g^(-1)after 1000 cycles at 1 C with an extremely low capacity fading rate 0.03%per cycle),and superior rate capability(747.5 mA h g^(-1)at 2 C).Accordingly,such Ni nanoparticles embedded in a renewable puffed corn-derived carbon prepared via a simple and effective route represent a promising active type of sulfur host matrix to fabricate high-performance Li-S batteries.

Defect-rich porous tubular graphitic carbon nitride with strong adsorption towards lithium polysulfides for high-performance lithium-sulfur batteries

The commercialization of the lithium-sulfur(Li-S)batteries is severely hampered by the shuttle effect and sluggish kinetics of lithium polysulfides(Li PSs).In this study,porous tubular graphitic carbon nitride(PTCN)was synthesized as the sulfur host by hydrothermal treatment,thermal shock and etching methods.By etching technology,the hollow nanotube tentacles grow on the tube wall of PTCN,the mesoporous appears on the inner wall,and a large number of nitrogen defects are introduced.The verticallyrooted hollow nanotube tentacles on the PTCN surface facilitate electron conduction for sulfur redox reactions.The hollow and porous architecture exposes plentiful active interfaces for accelerated redox conversion of polysulfide.Furthermore,the nitrogen defects in PTCN enable more excellent intrinsic conductivity,higher adsorbability and conversion catalytic activity to Li PSs.Based on the above synergetic effect,the batteries with PTCN/S cathodes realize a high discharge capacity of 504 m Ah g^(-1) at 4 C and a stable cycling behavior over 500 cycles with a low capacity decay of 0.063%per cycle.The results indicate a promising approach todesigning a high performance electrode material for Li-S batteries.

Dealloying-derived nanoporous deficient titanium oxide as high-performance bifunctional sulfur host-catalysis material in lithium-sulfur battery

In this work,we report a facile dealloying strategy to tailor the surface state of nanoporous TiO_(2) towards high-efficiency sulfur host material for lithium-sulfur(Li-S)batteries.When used as a sulfur cathode material,the oxygen-deficient TiO_(2)-xexhibits enhanced lithium polysulfides(Li PS)adsorption and conversion kinetics that effectively tackle the shuttle effect in lithium-sulfur batteries.The excellent ability of the oxygen vacancy sites on TiO_(2)-xsurface to trap Li PS is proved by experimental observations and density functional theory(DFT)calculations.Meanwhile,it also promotes conversion kinetics of lithium polysulfides,as verified by the asymmetric cell experiment.Accordingly,compared with the S/TiO_(2) cathode,the oxygen-deficient S/TiO_(2)-xelectrode exhibits preeminent rate and cycling performance in lithium-sulfur batteries:it delivers an ultra-low capacity decay of 0.039%per cycle after 1000 cycles at 1 C.Tunning the surface state of metal oxides by dealloying method offers a new facile strategy to design efficient sulfur cathode materials for lithium-sulfur batteries.

Oxidized Nb_(2)C MXene as catalysts for lithium-sulfur batteries:Mitigating the shuttle phenomenon by facilitating catalytic conversion of lithium polysulfides

Extensive research has been devoted to lithium-sulfur(Li-S)batteries due to their overwhelming promises and advantages such as high theoretical capacity(1675 m Ah g^(-1)),extremely cost effectiveness and abundance and availability of sulfur.Nevertheless,a sluggish electrochemical kinetics of the battery limited by a slow conversion of lithium polysulfide(LiPSs)intermediates and Li PSs shuttle effect severely hinder its development towards industrial application.Herein,we designed the oxidized Nb2_(C)MXene with amorphous carbon(Nb_(2)O_(5)/C)composites as sulfur host using CO_(2)treatment to address the above issues.The Nb_(2)O_(5)/C composites with high conductivity are directly employed as sulfur hosts for Li-S battery capable to remarkably mitigate the shuttle phenomenon due to a combined effect of their Li PSs trapping ability and catalytic activity towards their accelerated conversion.Meanwhile,the unique layered structure of the composite facilitates ion transfer and accommodates the volume changes of the cathode during cycling.With this rational design,the resultant Li-S batteries exhibit superior electrochemical performance with a high initial specific capacity of 745 m Ah g^(-1)at 1.0 C and a reversible capacity of 620 m Ah g^(-1)at a high rate cycling at 3.0 C.