Polymer “Tape”-Assisted Ball-Milling Method Fabrication Few-Atomic-Layered Bismuth for Improving K^(+)/Na^(+)Storage

Few-layered 2D analogs exhibit new physical/chemical properties,leading to a strong research interest and broad areas of application.Recently,lots of methods(such as ultrasonic and electrochemical methods)have already used to prepared 2D materials.However,these methods suffer from the drawbacks of low yield,high cost,or precarious state,which limit the largescale applications.Inspired by the famous Scotch tape method,we develop a ball-milling with polymer"tape"method,fabricating few-atomic-layered material,showing the high-yield,low-cost,and much stability.As electrode material,ultrathin 2D materials can shorten the ion transfer pathway,contributing to the development of high-power batteries.Meanwhile,fewatomic-layered structure can expose more active sites to increase their capacity,showing special energy storage mechanism.We use the as-prepared few-atomic-layered Bi(FALB)and reduced oxide graphene composites as the anode for potassium/sodium-ion batteries(KIBs/NIBs).The sample achieves a high reversible capacity of 395 m Ah g^(-1)for KIBs,of which FALB contributes 438 m Ah g^(-1)(higher than the theoretical capacity of Bi,386 m Ah g^(-1)),and it carries outstanding cycle and rate performance in KIBs/NIBs.

Three-Layer Structured SnO_(2)@C@TiO_(2)Hollow Spheres for High-Performance Sodium Storage

The unsatisfactory conductivity and large volume variation severely handicap the application of SnO_(2)in sodium-ion batteries(SIBs).Herein,we design unique three-layer structured SnO_(2)@C@TiO_(2)hollow spheres to tackle the above-mentioned issues.The hollow cavity affords empty space to accommodate the volume variation of SnO_(2),while the C and TiO_(2)protecting shells strengthen the structural integrity and enhances the electrical conductivity.As a result,the three-layer structured SnO_(2)@C@TiO_(2)hollow spheres demonstrate enhanced Na storage performances.The SnO_(2)@C@TiO_(2)manifests a reversible capacity two times to that of pristine SnO_(2)hollow spheres.In addition,Ex situ XRD reveals highly reversible alloying and conversion reactions in SnO_(2)@C@TiO_(2)hollow spheres.This study suggests the introduction of a hollow cavity and robust protecting shells is a promising strategy for constructing SIB anode materials.

Mitigated lattice distortion and oxygen loss of Li-rich layered cathode materials through anion/cation regulation by Ti^(4+)-substitution

Lithium-rich layered cathode material(LLM)can meet the requirement of power lithium-ion energy storage devices due to the great energy density.However,the de/intercalation of Li+will cause the irreversible loss of lattice oxygen and trigger transition metal(TM)ions migrate to Li+vacancies,resulting in capacity decay.Here we brought Ti4+in substitution of TM ions in Li_(1.2)Mn_(0.54)Ni_(0.13)Co_(0.13)O_(2),which could stabilize structure and expand the layer spacing of LLM.Moreover,optimized Ti-substitution can regulate the anions and cations of LLM,enhance the interaction with lattice oxygen,increase Ni^(3+) and Co^(3+),and improve Mn^(4+) coordination,improving reversibility of oxygen redox activation,maintaining the stable framework and facilitating the Li^(+) diffusion.Furthermore,we found 5%Ti-substitution sample delivered a high discharge capacity of 244.2 mAh/g at 50 mA/g,an improved cycling stability to 87.3%after 100 cycles and enhanced rate performance.Thereby Ti-substitution gives a new pathway to achieve high reversible cycle retention for LLMs.

Boosting Li-ion storage in Li2MnO_(3) by unequal-valent Ti4+-substitution and interlayer Li vacancies building

Lithium rich layered oxide(LRLO) has been considered as one of the promising cathodes for lithium-ion batteries(LIBs). The high voltage and large capacity of LRLO depend on Li2MnO_(3)phase. To ameliorate the electrochemical performance of Li2MnO_(3), also written as Li(Li1/3Mn2/3)O_(2), we propose a strategy to substitute Mn4+and Li+in Mn/Li transition metal layer with Ti4+, which can stabilize the structure of Li2MnO_(3)by inhibiting the excessive oxidation of O_(2)-above 4.5 V. More significantly, the unequal-valent substitution brings about the emergence of interlayer Li vacancies, which can promote the Li-ion diffusion based on the enlarged interlayer and increase the capacity by activating the Mn3+/4+redox. We designed Li0.7[Li1/3Mn2/3]0.7Ti0.3O_(2)with high interlayer Li vacancies, which presents a high capacity(290 m Ah/g at 10 m A/g) and stable cycling performance(84% over 60 cycles at 50 m A/g). We predict that this strategy will be helpful to further improve the electrochemical performance of LRLOs.

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.

Low-coordination water Prussian white as cathode for high-performance potassium-ion batteries

Prussian whites(PWs) with a three-dimensional framework can accommodate the insertion and extraction of ions with large radius,which have been widely used in potassium ion batteries.However,PWs show the poor cycling performance and inferior rate ability because of high coordinated water.In this work,PWs with different water content were synthesized via a coprecipitation method by controlling the reaction temperature.The sample with low-coordination water prohibits the best electrochemical performance.It shows a high capacity of 120.5 mAh/g at 100 mA/g for potassium-ion batteries(KIBs).It also exhibits a good rate performance,displaying a capacity of 73.2 mAh/g at 500 mA/g.