Hierarchical carbon nanosheet confined defective MoS_(x) cathode towards long-cycling zinc-ion-battery

Aqueous zinc-ion batteries(ZIBs)have attracted increasing attention due to their low cost and high safety.MoS_(2) is a promising cathode material for aqueous ZIBs due to its favorable Zn^(2+)accommodation ability.However,the structural strain and large volume changes during intercalation/deintercalation lead to exfoliation of active materials from substrate and cause irreversible capacity fading.In this work,a highly stable cathode was developed by designing a hierarchical carbon nanosheet-confined defective MoS_(x)material(CNS@MoS_(x)).This cathode material exhibits an excellent cycling stability with high capacity retention of 88.3%and~100%Coulombic efficiency after 400 cycles at 1.2 A·g^(-1),much superior compared to bare MoS_(2).Density functional theory(DFT)calculations combined with experiments illustrate that the promising electrochemical properties of CNS@MoS_(x)are due to the unique porous conductive structure of CNS with abundant active sites to anchor MoS_(x)via strong chemical bonding,enabling MoS_(x)to be firmly confined on the substrate.Moreover,this unique hierarchical complex structure ensures the fast migration of Zn^(2+)within MoS_(x)interlayer.

Al_2O_3 coated LiCoO_2 as cathode for high-capacity and long-cycling Li-ion batteries

Lithium-ion batteries(LIBs) as energy storage devices play an important role in all aspects of our life. The increasing energy demand of the society requires LIBs with higher energy density and better performance. We here develop a new and easy-to-scaleup sol-gel method to coat a surface protection layer on commercial LiCoO2cathode. We demonstrate that a proper thickness can improve the cycling life with a higher cut-off potential(4.5 V), larger energy capacity(180 mAh/g at 0.5 C) and better energy density(35% more compared to non-coated LiCoO2). The mechanism of the protection layer is also revealed by a combination of electron microscopy and synchrotron X-ray spectroscopy.

Long cycle performance of NC@VN/MnO cathode for AZIBs based on Mn/V relay type collaboration

Aqueous zinc ion batteries(AZIBs) have received great attention because of their non-toxicity,high safety,low cost,high abundance,and high specific power.However,their specific capacity is still low compared with lithium ion battery,and current academic research interesting has been focused on developing new cathode materials with high specific capacity.In this study,a Mn/V hybrid polymer framework is designed by a simple self-polymerization scheme.During subsequent calcination,ultrafine VN quantum dots and MnO nanoparticles are generated in situ and stably encapsulated inside N-doped carbon(NC) shells to obtain a novel hybrid cathode NC@VN/MnO for AZIBs.According to the density functional theory(DFT) calculation,the hybrids of MnO and VN can generate both interfacial effects and built-in electric fields that significantly accelerate ion and electron transport by tuning the intrinsic electronic structure,thus enhancing electrochemical performance.A synergistic strategy of composition and structural design allows the rechargeable AZIBs to achieve low-cost and excellent long-cycle performance based on a relay type collaboration at different cycling stages.Consequently,the NC@VN/MnO cathode has output a capacity of 108.3 mA h g^(-1)after 12,000 cycles at 10 A g^(-1).These results clearly and fully demonstrate the advantages of the hybrid cathode NC@VN/MnO.

A flexible design strategy to modify Ti3C2Tx MXene surface terminations via nucleophilic substitution for long-life Li-S batteries

MXene-based materials have gained considerable attention for lithium-sulfur(Li-S)batteries cathode materials due to their superior electric conductivity and high affinitive to polysulfides.However,there are still challenges in modifying the surface functional groups of MXene to further improve the electrochemical performance and increase the structure variety for MXene-based sulfur host.Herein,we report an efficient and flexible nucleophilic substitution(S_(N))strategy to modify the Ti_(3)C_(2)T_(x) surface terminations and purposefully designed Magnolol-modified Ti_(3)C_(2)T_(x)(M-Ti_(3)C_(2)T_(x))as powerful cathode host materials.Benefiting from more C-Ti-O bonds forming and diallyl groups terminations reducing after the dehalogenation and nucleophilic addition reactions,the given M-Ti_(3)C_(2)T_(x) electrode could effectively suppress the lithium polysulfides shuttling via chemisorption and C—S covalent bond formation.Besides,the Magnolol-modified Ti_(3)C_(2)T_(x) significantly accelerates polysulfide redox reaction and reduces the activation energy of Li_(2) S decomposition.As a result,the as-prepared M-Ti_(3)C_(2)T_(x) electrode displays an excellent rate capability and a high reversible capacity of 7.68 mAh cm^(-2)even under 7.2 mg cm^(-2)S-loaded with a low decay rate of 0.07%(from 2 nd cycle).This flexible surface-modified strategy for MXene terminations is expected to be extended to other diverse MXene applications.

Quench-tailored Al-doped V_(2)O_(5) nanomaterials for efficient aqueous zinc-ion batteries

Rechargeable aqueous zinc-ion batteries(ZIBs)are regarded as a promising competition to lithium-ion batteries as energy storage devices,owing to their high safety and low cost.However,the development of high-performance ZIBs is largely hindered by the shortage of ideal cathode materials with high-rate capability and long-cycle stability.Herein,we address this bottleneck issue by the quenching-tailored surface chemistry of V_(2)O_(5) cathode nanomaterial.By rapid quenching from high temperatures,Al ions are doped into V_(2)O_(5) lattice(Al-V_(2)O_(5))and abundant oxygen vacancies are formed on the surface/nearsurface,which facilitate the desired rapid electron transfers.Our density functional theory(DFT)simulations elucidate that the doping of Al ions into V_(2)O_(5) remarkably reduces the Zn^(2+)-diffusion barriers and improves the electrical conductivity of V_(2)O_(5).As a proof-of-concept application,the thus-optimized AlV_(2)O_(5) cathode delivers a superior specific capacity of 532 m Ah g^(-1) at 0.1 A g^(-1) and a long-cycling life with76%capacity retention after 5000 cycles,as well as a good rate performance.This work provides not only a novel strategy for tuning the surface chemistry of V_(2)O_(5) to boost the Zn^(2+)storage but also a general pathway of modifying metal oxides with improved electrochemical performance.

Eliminating H_(2)O/HF and regulating interphase with bifunctional tolylene-2,4-diisocyanate(TDI)additive for long life Li-ion battery

Lithium-ion batteries(LIBs)featuring a Ni-rich cathode exhibit increased specific capacity,but the establishment of a stable interphase through the implementation of a functional electrolyte strategy remains challenging.Especially when the battery is operated under high temperature,the trace water present in the electrolyte will accelerate the hydrolysis of the electrolyte and the resulting HF will further erode the interphase.In order to enhance the long-term cycling performance of graphite/LiNi_(0.8)Co_(0.1)Mn_(0.1)O_(2)(NCM811)LIBs,herein,Tolylene-2,4-diisocyanate(TDI)additive containing lone-pair electrons is employed to formulate a novel bifunctional electrolyte aimed at eliminating H_(2)O/HF generated at elevated temperature.After 1000 cycles at 25℃,the battery incorporating the TDI-containing electrolyte exhibits an impressive capacity retention of 94%at 1 C.In contrast,the battery utilizing the blank electrolyte has a lower capacity retention of only 78%.Furthermore,after undergoing 550 cycles at 1 C under45℃,the inclusion of TDI results in a notable enhancement of capacity,increasing it from 68%to 80%.This indicates TDI has a favorable influence on the cycling performance of LIBs,especially at elevated temperatures.The analysis of the film formation mechanism suggests that the lone pair of electrons of the isocyanate group in TDI play a crucial role in inhibiting the generation of H_(2)O and HF,which leads to the formation of a thin and dense interphase.The existence of this interphase is thought to substantially enhance the cycling performance of the LIBs.This work not only improves the performance of graphite/NCM811 batteries at room temperature and high temperature by eliminating H_(2)O/HF but also presents a novel strategy for advancing functional electrolyte development.

A novel in situ wrappingapproach leads to long-cycle stable cathode for lithium sulfur (Li-S) batteries

With the support by the National Natural Science Foundation of China,the research group led by Prof.Chen Liwei(陈立桅)at the Suzhou Institute of Nano-Tech and Nano-Bionics(SINANO),Chinese Academy of Sciences in collaboration with Prof.Chen Hongwei(陈宏伟)from Huaqiao University demonstrated a novel in situ wrapping strategy that leads to long-cycle life cathode for Li-S batteries,which was published in Nature Communications(2017,8:479).

Three-dimensional nanostructured Co_(2)VO_(4)-decorated carbon nanotubes for sodium-ion battery anode materials

Since Co_(2)VO_(4) possesses a solid spinel structure and a high degree of stability,it has gained interest as a possible anode material for sodium-ion batteries.However,the application of this electrode material is still hampered by its poor electrical conductivity and severe volume expansion.Uniform Co_(2)VO_(4) nanoparticles(CVO)were grown on carbon nanotubes(CNTs)by a simple solvothermal method to form string-like conductive networks(CVO/CNTs).The flexible and highly conductive three-dimensional(3D)carbon nano tubes and small-sized CVO NPs can enhance the rapid transport of electrons,thereby enhancing the conductivity of the composite.String-like conductive network structures have a larger specific surface area,enhancing electron/ion transmission by fully contacting the electrolyte.The findings demonstrate the superior Na^(+)storing capability of the CVO/CNTs composite.The battery has a great rate performance(148.2 mAh·g^(-1)at 5 A·g^(-1))and outstanding long-term cycling performance(147.3 mAh·g^(-1)after 1000 cycles at 1A·g^(-1)).In high-rate,long-cycle sodium-ion batteries,CVO/CNTs composites offer a wide range of possible applications.