Approaching high-performance lithium storage materials by constructing Li_(2)ZnTi_(3)O_(8)@LiAlO_(2) composites

The Li_(2)ZnTi_(3)O_(8)@Li AlO_(2)was synthesized by a facile high-temperature solid-state route.The LiAlO_(2)modification does not alter the morphology and particle size of Li_(2)Zn Ti_(3)O_(8)(LZTO).The LiAlO_(2)modification improves the structure stability,intercalation/deintercalation reversibility of lithium-ions,and electrochemical reaction activity of Li_(2)Zn Ti_(3)O_(8),and promotes the transfer of lithium ions.Benefited from the unique component,Li_(2)Zn Ti_(3)O_(8)@Li AlO_(2)(8wt%) shows a good rate performance with charge capacities of 203.9,194.8,187.4,180.6,and177.1 mAh·g^(-1)at 0.5,1,2,3,and 5 C,respectively.Nevertheless,pure LZTO only delivers charge capacities of 134.5,109.7,89.4,79.9,and 72.9 mAh·g^(-1)at the corresponding rates.Even at large charge–discharge rate,the Li_(2)Zn Ti_(3)O_(8)@Li AlO_(2)(8wt%) composite indicates a good cycle performance with a high reversible charge/discharge capacity of 263.5/265.8 mAh·g^(-1)at 5 C after 150 cycles.The introduction of LiAlO_(2)on the surface of Li_(2)Zn Ti_(3)O_(8)enhances electronic conductivity of the composite,resulting in the good electrochemical performance of Li_(2)Zn Ti_(3)O_(8)@Li AlO_(2)composite.Li_(2)Zn Ti_(3)O_(8)@LiAlO_(2)(8wt%) composite shows a good potential as an anode material for the next generation of high-performance Li-ion batteries.

Ge nanoparticles uniformly immobilized on 3D interconnected porous graphene frameworks as anodes for high-performance lithium-ion batteries

Germanium(Ge), an alloy-type anode material for lithium-ion batteries(LIBs), possesses many advantages such as high theoretical capacity and decent electrical conductivity. Nevertheless, its application is restricted by tremendous volume variation and tardy reaction kinetic during discharge/charge process.In this paper, the Ge/3DPG composites with Ge nanoparticles uniformly dispersed in 3D interconnected porous graphene(3DPG) skeleton are successfully prepared using a template-assisted in-situ reduction method. The unique 3D interconnected porous graphene can not only enhance the electronic conductivity and reaction kinetics of the materials, but also provide sufficient buffer space to effectively mitigate the volume expansion during cycling and strengthen the structural integrity. Moreover, the small-sized Ge nanoparticles in close conjunction with the 3D graphene can boost the surface-controlled reaction of the electrode, which contributes to a fast charge–discharge rate capability. The Ge/3DPG composite with optimized Ge/graphene mass ratio delivers high reversible specific capacity(1102 mAh g^(-1) after 100 cycles at 0.2 C), outstanding rate capability(494 mAh g^(-1) at 5 C), and admirable cycling stability(85.3% of capacity retention after 250 cycles at 0.5 C). This work provides a significant inspiration for the design and fabrication of advanced Ge-based anode materials for next-generation highperformance LIBs.

Bimetallic CoNiSe_(2)/C nanosphere anodes derived from Ni-Co-metal-organic framework precursor towards higher lithium storage capacity

Through uncomplicated carbonation process,a carbon-embedded CoNiSe_(2)/C nanosphere was synthesized from Ni-Co-MOF (metal-organic framework) precursor whose controllable structure and synergistic effect of bimetallic Ni/Co brought CoNiSe_(2)/C anodes with high specific surface area (172.79 m^(2)/g) and outstanding electrochemical performance.CoNiSe_(2)/C anodes obtained reversible discharge capacities of850.9 mAh/g at 0.1 A/g after cycling for 100 cycles.In addition,CoNiSe_(2)/C exhibits excellent cycle stability and reversibility in the rate test at a current density of 0.1–2.0 A/g.When the current density returns to 0.5 A/g for 150 cycles,its discharge ratio the capacity is 330.8 m Ah/g.Electrochemical impedance spectroscopy (EIS) tests suggested that CoNiSe_(2)/C anodes had a lower charge transfer impedance of 130.02Ωafter 30 cycles.In-situ X-ray diffraction (XRD) tests confirmed the alloying mechanism of CoNiSe_(2)/C which realized higher lithium storage capacity.This work affords substantial evidence for the extension of bimetallic selenides in secondary batteries,promoting the development of bimetallic selenides in anode materials for LIBs.

Self-template synthesis of peapod-like MnO@N-doped hollow carbon nanotubes as an advanced anode for lithium-ion batteries

The exploration of low-cost and high-performance transition metal oxides/carbon(TMOs/C)-based anodes to replace commercial graphite is still a huge challenge for the development of lithium-ion batteries(LIBs).In this work,MnO@N-doped hollow carbon nanotubes(MnO@NHCNT-v,v refers to the adding volume of pyrrole)hybrids are successfully prepared by a facile selftemplate strategy using Mn3O4 nanotubes(Mn3O4 NT)and pyrrole(PY)as the precursors.The morphology,structure and composition of these MnO@NHCNT-v samples are systematically investigated.And the effect of PY adding amounts on the synthesis of MnO@NHCNT-v samples is also explored.The results show that the Mn_(3)O_(4) NT works as a self-template,which releases Mn3+and guides the growth of polypyrrole(PPY)on Mn_(3)O_(4) NT.Meanwhile,it is demonstrated that the synthesis of MnO@NHCNTv hybrids can be well regulated by the added PY amounts.As a result,MnO@NHCNT-1 hybrid not only makes a good balance on the proportion of MnO and carbon matrix but also simultaneously obtains unique peapod-like structure and successful N doping in NHCNT,resulting in good electrical contact between the two components,enhanced chemical binding by Mn-N-C bonds and enough void space inside its microstructure.Benefitting from these merits,the resulting MnO@NHCNT-1 hybrid exhibits outstanding cycling stability and rate capability when used as a LIBs anode.Our work offers a good guidance on the design and preparation of low-price and high-performance TMOs/C-based LIBs anodes.

Metal oxyacid salts-confined pyrolysis towards hierarchical porous metal oxide@carbon(MO@C)composites as lithium-ion battery anodes

Transition metal oxides(TMOs)have been thought of potential anodic materials for lithium-ion batteries(LIBs)owing to their intriguing properties.However,the limited conductivity and drastic volume change still hinder their practical applications.Herein,a metal oxyacid salts-confined pyrolysis strategy is proposed to construct hierarchical porous metal oxide@carbon(MO@C,MO=MoO_(2),V_(2)O_(5),WO_(3))composites for solving the aforementioned problems.A water-evaporation-induced self-assembly mechanism has been put forward for fabricating the MO@polyvinyl pyrrolidone(PVP)@SiO_(2)precursors.After the following pyrolysis and etching process,small MO nanoparticles can be successfully encapsulated in the hierarchical porous carbon framework.Profiting from the synergistic effect of MO nanoparticles and highly conductive carbon framework,MO@C composites show excellent electrochemical properties.For example,the as-obtained MoO_(2)@C composite exhibits a large discharge capacity(1513.7 mAh·g^(−1)at 0.1 A·g^(−1)),good rate ability(443.5 mAh·g^(−1)at 5.0 A·g^(−1)),supernal long-lived stability(669.1 mAh·g^(−1)after 1000 cycles at 1.0 A·g^(−1)).This work will inspire the design of novel anode materials for high-performance LIBs.

Boosting the high-rate performance and cycling life of NaTi_(2)(PO_(4))_(3) anode by forming N-doped carbon coating derived from polyacrylonitrile

Poor electron conductivity is the key issue influencing the rate capability of NaTi_(2)(PO_(4))_(3)(NTP).Hence,herein,polyacrylonitrile(PAN)was utilized as a NTP modifier by simply mixing NTP in a liquid PAN suspension,followed by sintering at 850℃ for 5 h.The product with a PAN/NTP mass ratio of 0.3 delivered splendid rate capabilities(achieving lithiation capacities of 282.9,243.0,207.1,173.1,133.5,and 257.5 mAh g^(−1) at 0.1,0.2,0.4,0.8,1.6,and 0.1 A^(−1),respectively)and excellent long cycling life(capacity retention of 165.5 mAh g^(−1) after 1200 cycles at 0.5 A g−1).Based on detailed structural and compositional characterizations,as well as cyclic voltammetry(CV)and electrochemical impedance spectroscopy(EIS),the uniform N-doped carbon coating stemming from PAN carbonization around the NTP particles promoted electron transfer,while the oxygen vacancies induced by N-doping in NTP facilitated Li+diffusion.The boosted and well matched electronic and ionic conductivities give rise to the optimized electrochemical performance.

A novel Mo-based oxide β-SnMoO4 as anode for lithium ion battery

Recently,the development of new electrode materials for lithium-ion batteries(LIBs)has received intensive attention.As an important family of inorganic materials,mixed Mo-based transition metal oxides system is focused as anode materials.In the present work,a simple route has been adopted for the synthesis of layered-flake-likeβ-SnMo04 Nano-assemblies,which have been explored as potential anode materials for the first time in lithium-ion battery(LIB).Overall,the current reports on metal molybdate as anode materials are still rarely.As the anode material for LIBs,it was observed that the fabricated anode is capable of delivering a steady state capacity of almost 400 mAh/g up to 300 cycles under the influence of200 mA/g current density.Further,the anode material is suitable for use as a rated capacity anode because of its high current density tolerance.The present study can be further extended for the generation of a wide variety of other novel materials for multidisciplinary energy related applications.