In this work, a scalable and cost-effective method including mechanical milling, centrifugation and spray drying was developed to fabricate Si nanoparticles.The synthesized Si nanoparticles show an average size of 62 ...In this work, a scalable and cost-effective method including mechanical milling, centrifugation and spray drying was developed to fabricate Si nanoparticles.The synthesized Si nanoparticles show an average size of 62 nm and exhibit a narrow particle size distribution. The influence of particle sizes on electrochemical performance of Si-based electrode was investigated, and it is found that as the particle size decreases in the studied range, the Si particles show a lower specific capacity and a higher irreversible capacity loss(ICL). Furthermore, an oxide layer with thickness of ～3 nm was detected on the surface of the as-received Si nanoparticles, and this layer can be effectively removed by hydrofluoric acid(HF) etching,resulting in much improved electrochemical performance over the as-received samples.展开更多
Polymer binder plays a pivotal role in electrochemical performance of high-capacity silicon(Si)anode that usually suffers from severe capacity fading due to enormous substantial volume change of Si during cycling.In a...Polymer binder plays a pivotal role in electrochemical performance of high-capacity silicon(Si)anode that usually suffers from severe capacity fading due to enormous substantial volume change of Si during cycling.In an effort to find efficient polymer binder that could mitigate such capacity fading,alginate-carboxymethyl chitosan(Alg-C-chitosan)composite polymer was investigated as a low-cost watersoluble binder for silicon anodes in lithium-ion batteries.The electrostatic interaction between carboxylate(-COO-)of Alg and protonated amines(-NH3+)of C-chitosan forms a selfhealing porous scaffold structure.Synergistic effect on the enhanced porous scaffold structure and self-healing electrostatic interaction of Alg-C-chitosan binder effectively can tolerate the tremendous volume change of Si and maintain an integrated electrode structure during cycling process.The Si nanopowder electrodes with Alg-C-chitosan composite binder exhibit an excellent cycling stability,with a capacity of750 mAh·g-1 remaining after 100 th cycling.In addition,an extraordinary areal capacity of 3.76 mAh·cm-2 is achieved for Si-based anodes with Alg-C-chitosan binder.展开更多
Silicon has been recognized as the most promising anode material for high capacity lithium ion batteries. However, large volume variations during charge and discharge result in pulverization of Si electrodes and fast ...Silicon has been recognized as the most promising anode material for high capacity lithium ion batteries. However, large volume variations during charge and discharge result in pulverization of Si electrodes and fast capacity loss on cycling. This drawback of Si electrodes can be overcome by combination with well-organized graphene foam. In this work, hierarchical three-dimensional carbon-coated mesoporous Si nanospheres@graphene foam （C@Si@GF） nanoarchitectures were successfully synthesized by a thermal bubble ejection assisted chemical-vapor-deposition and magnesiothermic reduction method. The morphology and structure of the as-prepared nanocomposites were characterized by field emission scanning electron microscopy, transmission electron microscopy and Raman spectroscopy. When employed as anode materials in lithium ion batteries, C@Si@GF nanocomposites exhibited superior electrochemical per- formance including a high specific capacity of 1,200 mAh/g at the current density of 1A/g, excellent high rate capabilities and an outstanding cyclability. Post-mortem analyses identified that the morphology of 3D C@Si@GF electrodes after 200 cycles was well maintained. The synergistic effects arising from the combination of mesoporous Si nanospheres and graphene foam nanoarchitectures may address the intractable pulverization problem of Si electrode.展开更多
Rechargeable lithium batteries have been widely regarded as a revolutionary technology to store renewable energy sources and extensively researched in the recent several decades.As an indispensable part of lithium bat...Rechargeable lithium batteries have been widely regarded as a revolutionary technology to store renewable energy sources and extensively researched in the recent several decades.As an indispensable part of lithium batteries,the evolution of anode materials has significantly promoted the development of lithium batteries.However,since conventional lithium batteries with graphite anodes cannot meet the ever-increasing demands in different application scenarios(such as electric vehicles and large-scale power supplies)which require high energy/power density and long cycle life,various improvement strategies and alternative anode materials have been exploited for better electrochemical performance.In this review,we detailedly introduced the characteristics and challenges of four representative anode materials for rechargeable lithium batteries,including graphite,Li_(4)Ti_(5)O_(12),silicon,and lithium metal.And some of the latest advances are summarized,which mainly contain the modification strategies of anode materials and partially involve the optimization of electrode/electrolyte interface.Finally,we make the conclusive comments and perspectives,and draw a development timeline on the four anode materials.This review aims to offer a good primer for newcomers in the lithium battery field and benefit the structure and material design of anodes for advanced rechargeable lithium batteries in the future.展开更多
Silicon(Si)is a promising anode candidate for next-generation lithium-ion batteries(LIBs),but it suffers from poor electronic conductivity and dramatic volume variation during cycling,which poses a critical challenge ...Silicon(Si)is a promising anode candidate for next-generation lithium-ion batteries(LIBs),but it suffers from poor electronic conductivity and dramatic volume variation during cycling,which poses a critical challenge for stable battery operation.To mitigate these issues simultaneously,we propose a"double carbon synergistic encapsulation"strategy,namely thin carbon shell and nitrogen/phosphorus co-doped two-dimensional(2D)carbon sheet dual encapsulate Si nanoparticles(denoted as 2D NPC/C@Si).This double carbon structure can serve as a conductive medium and buffer matrix to accommodate the volume expansion of Si nanoparticles and enable fast electron/ion transport,which promotes the formation of a stable solid electrolyte interphase film during cycling.Through structural advantages,the resulting 2 D NPC/C@Si electrode demonstrates a high reversible capacity of592 mAh·g^(-1) at 0.2 A·g^(-1) with 90.5%excellent capacity retention after 100 cycles,outstanding rate capability(148 mAh·g^(-1) at 8 A·g^(-1)),and superior long-term cycling stability(326 mAh·g^(-1) at 1 A·g^(-1) for 500 cycles,86%capacity retention).Our findings elucidate the development of high-performance Si@C composite anodes for advanced LTBs.展开更多
Silicon-based nanomaterials have been of scientific and commercial interest in lithium-ion batteries due to the low cost,low toxicity,and high specific capacity with an order of magnitude beyond that of conventional g...Silicon-based nanomaterials have been of scientific and commercial interest in lithium-ion batteries due to the low cost,low toxicity,and high specific capacity with an order of magnitude beyond that of conventional graphite.The poor capacity retention,caused by pulverization of Si during cycling,triggers researchers and engineers to explore better battery materials.This review summarizes recent work in improving Si-based anode materials via different approaches from diverse Si nanostructures,Si/metal nanocomposites,to Si/C nanocomposites,and also offers perspectives of the Si-based anode materials.展开更多
Silicon-based material is one of the most promising substitutes of widely used graphite anodes for the next generation Li-ion batteries due to its high theoretical capacity,low working potential,environmental friendli...Silicon-based material is one of the most promising substitutes of widely used graphite anodes for the next generation Li-ion batteries due to its high theoretical capacity,low working potential,environmental friendliness,and abundant natural resource.However,the huge volume expansion and serious interfacial side reactions during lithiation and delithiation progresses of the silicon anode are the key issues which impede their further practical applications.Rational designs of silicon nanostructures are effective ways to address these problems.In this progress report,we firstly highlight the fundamental scientific problems,and then focus on recent progresses in design,preparation,in-situ characterization methods and failure mechanism of nanostructured silicon anode for high capacity lithium battery.We also summarize the key lessons from the successes so far and offer perspectives and future challenges to promote the applications of silicon anode in practical lithium batteries.展开更多
Conventional lithium-ion batteries(LIBs)with graphite anodes are approaching their theoretical limitations in energy density.Replacing the conventional graphite anodes with high-capacity Si-based anodes represents one...Conventional lithium-ion batteries(LIBs)with graphite anodes are approaching their theoretical limitations in energy density.Replacing the conventional graphite anodes with high-capacity Si-based anodes represents one of the most promising strategies to greatly boost the energy density of LIBs.However,the inherent huge volume expansion of Si-based materials after lithiation and the resulting series of intractable problems,such as unstable solid electrolyte interphase layer,cracking of electrode,and especially the rapid capacity degradation of cells,severely restrict the practical application of Sibased anodes.Over the past decade,numerous reports have demonstrated that polymer binders play a critical role in alleviating the volume expansion and maintaining the integrity and stable cycling of Si-based anodes.In this review,the state-of-the-art designing of polymer binders for Si-based anodes have been systematically summarized based on their structures,including the linear,branched,crosslinked,and conjugated conductive polymer binders.Especially,the comprehensive designing of multifunctional polymer binders,by a combination of multiple structures,interactions,crosslinking chemistries,ionic or electronic conductivities,soft and hard segments,and so forth,would be promising to promote the practical application of Si-based anodes.Finally,a perspective on the rational design of practical polymer binders for the large-scale application of Si-based anodes is presented.展开更多
Silicon has attracted much attention as a promising anode material for lithium-ion batteries (LIBs) due to its high theoretical capacity and rich resource abundance. However, the practical battery use of Si is challen...Silicon has attracted much attention as a promising anode material for lithium-ion batteries (LIBs) due to its high theoretical capacity and rich resource abundance. However, the practical battery use of Si is challenged by its low conductivity and drastic volume variation during the Li uptake/release process. Tremendous efforts have been made on shrinking the particle size of Si into nanoscale so that the volume variation could be accommodated. However, the bare nano-Si material would still pulverize upon (de)lithiation. Moreover, it shows an excessive surface area to invite unlimited growth of solid electrolyte interface that hinders the transportation of charge carriers, and an increased interparticle resistance. As a result, the Si nanoparticles gradually lose their electrical contact during the cycling process, which accounts for poor thermodynamic stability and sluggish kinetics of the anode reaction versus Li. To address these problems and improve the Li storage performance of nano-Si anode, proper structural design should be applied on the Si anode. In this perspective, we will briefly review some strategies for improving the electrochemistry versus Li of nano-Si materials and their derivatives, and show opinions on the optimal design of nanostructured Si anode for advanced LIBs.展开更多
Nanoporous silicon is a promising anode material for high energy density batteries due to its high cycling stability and high tap density compared to other nanostructured anode materials.However,the high cost of synth...Nanoporous silicon is a promising anode material for high energy density batteries due to its high cycling stability and high tap density compared to other nanostructured anode materials.However,the high cost of synthesis and low yield of nanoporous silicon limit its practical application.Here,we develop a scalable,low-cost top-down process of controlled oxidation of Mg2Si in the air,followed by HCl removal of MgO to generate nanoporous silicon without the use of HF.By controlling the synthesis conditions,the oxygen content,grain size and yield of the porous silicon are simultaneously optimized from commercial standpoints.In situ environmental transmission electron microscopy reveals the reaction mechanism;the Mg2Si microparticle reacts with O2 to form MgO and Si,while preventing SiO2 formation.Owing to the low oxygen content and microscale secondary structure,the nanoporous silicon delivers a higher initial reversible capacity and initial Coulombic efficiency compared to commercial Si nanoparticles(3,033 mAh/g vs.2,418 mAh/g,84.3%vs.73.1%).Synthesis is highly scalable,and a yield of 90.4%is achieved for the porous Si nanostructure with the capability to make an excess of 10 g per batch.Our synthetic nanoporous silicon is promising for practical applications in next generation lithium-ion batteries.展开更多
Porous silicon(Si)nanostructures have aroused much interest as lithium-ion battery anodes because of the large space to accommodate the volume change in lithiation and delithiation and shorter ion transfer distance.Ho...Porous silicon(Si)nanostructures have aroused much interest as lithium-ion battery anodes because of the large space to accommodate the volume change in lithiation and delithiation and shorter ion transfer distance.However,fabrication of porous structures tends to be difficult to control and complex,so,the final electrochemical performance can be compromised.Herein,a modest magnesiothermic reduction(MMR)reaction is demonstrated to produce blackberry-like porous Si nanospheres(PSSs)controllably using magnesium silicide(Mg_(2)Si)as Mg source and SiO_(2)nanospheres as the reactant.This improved MR method provides good control of the kinetics and heat release compared to the traditional MR(TMR)method using Mg powder as the reactant.The PSSs obtained by MMR reaction has higher structural integrity than that fabricated by TMR.After encapsulation with reduced graphene oxide,the Si/C composite exhibits superior cycling stability and rates such as a high reversible capacity of 1034 mAh·g^(-1)at0.5 C(4200 mAh·g^(-1)at 1.0 C)after 1000 cycles,capacity retention of 79.5%,and high rate capacity of 497 mAh·g^(-1)at 2.0 C.This strategy offers a new route to fabricate highperformance porous Si anodes and can be extended to other materials such as germanium.展开更多
Li-ion batteries(LIBs)have demonstrated great promise in electric vehicles and hybrid electric vehicles.However,commercial graphite materials,the current predominant anodes in LIBs,have a low theoretical capacity of o...Li-ion batteries(LIBs)have demonstrated great promise in electric vehicles and hybrid electric vehicles.However,commercial graphite materials,the current predominant anodes in LIBs,have a low theoretical capacity of only 372 mAh·g?1,which cannot meet the everincreasing demand of LIBs for high energy density.Nanoscale Si is considered an ideal form of Si for the fabrication of LIB anodes as Si–C composites.Synthesis of nanoscale Si in a facile,cost-effective way,however,still poses a great challenge.In this work,nanoscale Si was prepared by a controlled magnesiothermic reaction using diatomite as the Si source.It was found that the nanoscale Si prepared under optimized conditions(800°C,10 h)can deliver a high initial specific capacity(3053 mAh·g?1 on discharge,2519 mAh·g?1 on charge)with a high first coulombic efficiency(82.5%).When using sand-milled diatomite as a precursor,the obtained nanoscale Si exhibited a well-dispersed morphology and had a higher first coulombic efficiency(85.6%).The Si–C(Si:graphite=1:7 in weight)composite using Si from the sand-milled diatomite demonstrated a high specific capacity(over 700 mAh·g?1 at 100 mA·g?1),good rate capability(587 mAh·g?1 at 500 mA·g?1),and a long cycle life(480 mAh·g?1 after 200 cycles at 500 mA·g?1).This work gives a facile method to synthesize nanoscale Si with both high capacity and high first coulombic efficiency.展开更多
Dramatic capacity fading and poor rate performance are two main obstacles that severely hamper the widespread application of the Si anode owing to its large volume variation during cycling and low intrinsic electrical...Dramatic capacity fading and poor rate performance are two main obstacles that severely hamper the widespread application of the Si anode owing to its large volume variation during cycling and low intrinsic electrical conductivity.To mitigate these issues,free-standing N-doped porous carbon nanofibers sheathed pumpkin-like Si/C composites(Si/C-ZIF-8/CNFs)are designed and synthesized by electrospinning and carbonization methods,which present greatly enhanced electrochemical properties for lithium-ion battery anodes.This particular structure alleviates the volume variation,promotes the formation of stable solid electrolyte interphase(SEI)film,and improves the electrical conductivity.As a result,the as-obtained free-standing Si/C-ZIF-8/CNFs electrode delivers a high reversible capacity of 945.5 mAh g^(-1) at 0.2 A g^(-1) with a capacity retention of 64% for 150 cycles,and exhibits a reversible capacity of 538.6 mA h g^(-1) at 0.5 A g^(-1) over 500 cycles.Moreover,the full cell composed of a freestanding Si/C-ZIF-8/CNFs anode and commercial LiNi_(1/3)Co_(1/3)Mn_(1/3)O_(2)(NCM)cathode shows a capacity of 63.4 mA h g^(-1) after 100 cycles at 0.2 C,which corresponds to a capacity retention of 60%.This rational design could provide a new path for the development of high-performance Si-based anodes.展开更多
基金financially supported by the National Natural Science Foundation of China (No. 51404030)the National Key Technologies Research and Development Program (No. 2016YFB0100400)+2 种基金the Natural Science Foundation of Beijing Municipality (No. 3154043)the Beijing Science and Technology Plan (No. Z151100000115015)the Beijing Nova Program (No. Z161100004916096)
文摘In this work, a scalable and cost-effective method including mechanical milling, centrifugation and spray drying was developed to fabricate Si nanoparticles.The synthesized Si nanoparticles show an average size of 62 nm and exhibit a narrow particle size distribution. The influence of particle sizes on electrochemical performance of Si-based electrode was investigated, and it is found that as the particle size decreases in the studied range, the Si particles show a lower specific capacity and a higher irreversible capacity loss(ICL). Furthermore, an oxide layer with thickness of ～3 nm was detected on the surface of the as-received Si nanoparticles, and this layer can be effectively removed by hydrofluoric acid(HF) etching,resulting in much improved electrochemical performance over the as-received samples.
基金financially supported by the National Natural Science Foundation of China (No. 51404032)the National High Technology Research and Development Program of China(No. 2013AA050904)
文摘Polymer binder plays a pivotal role in electrochemical performance of high-capacity silicon(Si)anode that usually suffers from severe capacity fading due to enormous substantial volume change of Si during cycling.In an effort to find efficient polymer binder that could mitigate such capacity fading,alginate-carboxymethyl chitosan(Alg-C-chitosan)composite polymer was investigated as a low-cost watersoluble binder for silicon anodes in lithium-ion batteries.The electrostatic interaction between carboxylate(-COO-)of Alg and protonated amines(-NH3+)of C-chitosan forms a selfhealing porous scaffold structure.Synergistic effect on the enhanced porous scaffold structure and self-healing electrostatic interaction of Alg-C-chitosan binder effectively can tolerate the tremendous volume change of Si and maintain an integrated electrode structure during cycling process.The Si nanopowder electrodes with Alg-C-chitosan composite binder exhibit an excellent cycling stability,with a capacity of750 mAh·g-1 remaining after 100 th cycling.In addition,an extraordinary areal capacity of 3.76 mAh·cm-2 is achieved for Si-based anodes with Alg-C-chitosan binder.
文摘Silicon has been recognized as the most promising anode material for high capacity lithium ion batteries. However, large volume variations during charge and discharge result in pulverization of Si electrodes and fast capacity loss on cycling. This drawback of Si electrodes can be overcome by combination with well-organized graphene foam. In this work, hierarchical three-dimensional carbon-coated mesoporous Si nanospheres@graphene foam （C@Si@GF） nanoarchitectures were successfully synthesized by a thermal bubble ejection assisted chemical-vapor-deposition and magnesiothermic reduction method. The morphology and structure of the as-prepared nanocomposites were characterized by field emission scanning electron microscopy, transmission electron microscopy and Raman spectroscopy. When employed as anode materials in lithium ion batteries, C@Si@GF nanocomposites exhibited superior electrochemical per- formance including a high specific capacity of 1,200 mAh/g at the current density of 1A/g, excellent high rate capabilities and an outstanding cyclability. Post-mortem analyses identified that the morphology of 3D C@Si@GF electrodes after 200 cycles was well maintained. The synergistic effects arising from the combination of mesoporous Si nanospheres and graphene foam nanoarchitectures may address the intractable pulverization problem of Si electrode.
基金supported by grants from the Natural Science Foundation of Jiangsu Province(BK20180098)the Open Research Fund of National Laboratory of Solid State Microstructures of Nanjing University(M32045&M33042)。
文摘Rechargeable lithium batteries have been widely regarded as a revolutionary technology to store renewable energy sources and extensively researched in the recent several decades.As an indispensable part of lithium batteries,the evolution of anode materials has significantly promoted the development of lithium batteries.However,since conventional lithium batteries with graphite anodes cannot meet the ever-increasing demands in different application scenarios(such as electric vehicles and large-scale power supplies)which require high energy/power density and long cycle life,various improvement strategies and alternative anode materials have been exploited for better electrochemical performance.In this review,we detailedly introduced the characteristics and challenges of four representative anode materials for rechargeable lithium batteries,including graphite,Li_(4)Ti_(5)O_(12),silicon,and lithium metal.And some of the latest advances are summarized,which mainly contain the modification strategies of anode materials and partially involve the optimization of electrode/electrolyte interface.Finally,we make the conclusive comments and perspectives,and draw a development timeline on the four anode materials.This review aims to offer a good primer for newcomers in the lithium battery field and benefit the structure and material design of anodes for advanced rechargeable lithium batteries in the future.
基金financially supported by the National Natural Science Foundation of China(Grant Nos.52072323,21805278 and 51872098)the Leading Project Foundation of Science Department of Fujian Province(No.2018H0034)+2 种基金the“Double-First Class”Foundation of Materials and Intelligent Manufacturing Discipline of Xiamen Universitythe Opening Project of National Joint Engineering Research Center for Abrasion Control and Molding of Metal MaterialsHenan Key Laboratory of High-temperature Structural and Functional Materials,Henan University of Science and Technology(No.HKDNM2019013)。
文摘Silicon(Si)is a promising anode candidate for next-generation lithium-ion batteries(LIBs),but it suffers from poor electronic conductivity and dramatic volume variation during cycling,which poses a critical challenge for stable battery operation.To mitigate these issues simultaneously,we propose a"double carbon synergistic encapsulation"strategy,namely thin carbon shell and nitrogen/phosphorus co-doped two-dimensional(2D)carbon sheet dual encapsulate Si nanoparticles(denoted as 2D NPC/C@Si).This double carbon structure can serve as a conductive medium and buffer matrix to accommodate the volume expansion of Si nanoparticles and enable fast electron/ion transport,which promotes the formation of a stable solid electrolyte interphase film during cycling.Through structural advantages,the resulting 2 D NPC/C@Si electrode demonstrates a high reversible capacity of592 mAh·g^(-1) at 0.2 A·g^(-1) with 90.5%excellent capacity retention after 100 cycles,outstanding rate capability(148 mAh·g^(-1) at 8 A·g^(-1)),and superior long-term cycling stability(326 mAh·g^(-1) at 1 A·g^(-1) for 500 cycles,86%capacity retention).Our findings elucidate the development of high-performance Si@C composite anodes for advanced LTBs.
基金supported by the National Basic Research Program of China (2011CB935700 and 2012CB932900)the National Natural Science Foundation of China (91127044 and 21073205)the Chinese Academy of Sciences
文摘Silicon-based nanomaterials have been of scientific and commercial interest in lithium-ion batteries due to the low cost,low toxicity,and high specific capacity with an order of magnitude beyond that of conventional graphite.The poor capacity retention,caused by pulverization of Si during cycling,triggers researchers and engineers to explore better battery materials.This review summarizes recent work in improving Si-based anode materials via different approaches from diverse Si nanostructures,Si/metal nanocomposites,to Si/C nanocomposites,and also offers perspectives of the Si-based anode materials.
基金supported by the National Programs for Nano-Key Project (2017YFA0206700)the National Key R&D Program of China (2018YFB1502100)+2 种基金the National Natural Science Foundation of China (21835004)111 Project from the Ministry of Education of China (B12015)the Fundamental Research Funds for the Central Universities, Nankai University (63191711 and 63191416)
文摘Silicon-based material is one of the most promising substitutes of widely used graphite anodes for the next generation Li-ion batteries due to its high theoretical capacity,low working potential,environmental friendliness,and abundant natural resource.However,the huge volume expansion and serious interfacial side reactions during lithiation and delithiation progresses of the silicon anode are the key issues which impede their further practical applications.Rational designs of silicon nanostructures are effective ways to address these problems.In this progress report,we firstly highlight the fundamental scientific problems,and then focus on recent progresses in design,preparation,in-situ characterization methods and failure mechanism of nanostructured silicon anode for high capacity lithium battery.We also summarize the key lessons from the successes so far and offer perspectives and future challenges to promote the applications of silicon anode in practical lithium batteries.
基金Beijing National Laboratory for Molecular Sciences,Grant/Award Number:2019BMS20022National Natural Science Foundation of China,Grant/Award Number:22005314+3 种基金Strategic Priority Research Program of the Chinese Academy of Sciences,Grant/Award Number:XDA21070300The China Postdoctoral Science Foundation,Grant/Award Number:2019M660805The National Key R&D Program of China,Grant/Award Number:2019YFA0705600The Special Financial Grant from the China Postdoctoral Science Foundation,Grant/Award Number:2020T130658。
文摘Conventional lithium-ion batteries(LIBs)with graphite anodes are approaching their theoretical limitations in energy density.Replacing the conventional graphite anodes with high-capacity Si-based anodes represents one of the most promising strategies to greatly boost the energy density of LIBs.However,the inherent huge volume expansion of Si-based materials after lithiation and the resulting series of intractable problems,such as unstable solid electrolyte interphase layer,cracking of electrode,and especially the rapid capacity degradation of cells,severely restrict the practical application of Sibased anodes.Over the past decade,numerous reports have demonstrated that polymer binders play a critical role in alleviating the volume expansion and maintaining the integrity and stable cycling of Si-based anodes.In this review,the state-of-the-art designing of polymer binders for Si-based anodes have been systematically summarized based on their structures,including the linear,branched,crosslinked,and conjugated conductive polymer binders.Especially,the comprehensive designing of multifunctional polymer binders,by a combination of multiple structures,interactions,crosslinking chemistries,ionic or electronic conductivities,soft and hard segments,and so forth,would be promising to promote the practical application of Si-based anodes.Finally,a perspective on the rational design of practical polymer binders for the large-scale application of Si-based anodes is presented.
基金the financial support of this work by the National Natural Science Foundation of China (No.21773078)the Fundamental Research Funds for the Central Universities of China (Nos.2662015PY163 and 2662017JC025).
文摘Silicon has attracted much attention as a promising anode material for lithium-ion batteries (LIBs) due to its high theoretical capacity and rich resource abundance. However, the practical battery use of Si is challenged by its low conductivity and drastic volume variation during the Li uptake/release process. Tremendous efforts have been made on shrinking the particle size of Si into nanoscale so that the volume variation could be accommodated. However, the bare nano-Si material would still pulverize upon (de)lithiation. Moreover, it shows an excessive surface area to invite unlimited growth of solid electrolyte interface that hinders the transportation of charge carriers, and an increased interparticle resistance. As a result, the Si nanoparticles gradually lose their electrical contact during the cycling process, which accounts for poor thermodynamic stability and sluggish kinetics of the anode reaction versus Li. To address these problems and improve the Li storage performance of nano-Si anode, proper structural design should be applied on the Si anode. In this perspective, we will briefly review some strategies for improving the electrochemistry versus Li of nano-Si materials and their derivatives, and show opinions on the optimal design of nanostructured Si anode for advanced LIBs.
基金This work was supported by Samsung SDI.Part of this work was performed at the Stanford Nano Shared Facilities(SNSF)Stanford Nanofabrication Facility(SNF).
文摘Nanoporous silicon is a promising anode material for high energy density batteries due to its high cycling stability and high tap density compared to other nanostructured anode materials.However,the high cost of synthesis and low yield of nanoporous silicon limit its practical application.Here,we develop a scalable,low-cost top-down process of controlled oxidation of Mg2Si in the air,followed by HCl removal of MgO to generate nanoporous silicon without the use of HF.By controlling the synthesis conditions,the oxygen content,grain size and yield of the porous silicon are simultaneously optimized from commercial standpoints.In situ environmental transmission electron microscopy reveals the reaction mechanism;the Mg2Si microparticle reacts with O2 to form MgO and Si,while preventing SiO2 formation.Owing to the low oxygen content and microscale secondary structure,the nanoporous silicon delivers a higher initial reversible capacity and initial Coulombic efficiency compared to commercial Si nanoparticles(3,033 mAh/g vs.2,418 mAh/g,84.3%vs.73.1%).Synthesis is highly scalable,and a yield of 90.4%is achieved for the porous Si nanostructure with the capability to make an excess of 10 g per batch.Our synthetic nanoporous silicon is promising for practical applications in next generation lithium-ion batteries.
基金the National Natural Science Foundation of China(Nos.51974208 and51504171)the Major Project of Technology Innovation of Hubei Province(No.2018AAA011)+4 种基金the Special Project of Central Government for Local Science and Technology Development of Hubei Province(No.2019ZYYD024)the Innovation Group of Natural Science Foundation of Hubei Province(No.2019CFA020)Wuhan Yellow Crane Talents ProgramCity University of Hong Kong Applied Research Grant(ARG)(No.9667122)Hong Kong Research Grants Council(RGC)General Research Funds(GRF)(No.City U 11205617)。
文摘Porous silicon(Si)nanostructures have aroused much interest as lithium-ion battery anodes because of the large space to accommodate the volume change in lithiation and delithiation and shorter ion transfer distance.However,fabrication of porous structures tends to be difficult to control and complex,so,the final electrochemical performance can be compromised.Herein,a modest magnesiothermic reduction(MMR)reaction is demonstrated to produce blackberry-like porous Si nanospheres(PSSs)controllably using magnesium silicide(Mg_(2)Si)as Mg source and SiO_(2)nanospheres as the reactant.This improved MR method provides good control of the kinetics and heat release compared to the traditional MR(TMR)method using Mg powder as the reactant.The PSSs obtained by MMR reaction has higher structural integrity than that fabricated by TMR.After encapsulation with reduced graphene oxide,the Si/C composite exhibits superior cycling stability and rates such as a high reversible capacity of 1034 mAh·g^(-1)at0.5 C(4200 mAh·g^(-1)at 1.0 C)after 1000 cycles,capacity retention of 79.5%,and high rate capacity of 497 mAh·g^(-1)at 2.0 C.This strategy offers a new route to fabricate highperformance porous Si anodes and can be extended to other materials such as germanium.
基金the National Natural Science Foundation of China(No.51572238)Zhejiang Provincial Natural Science Foundation(No.LY19E020013)the Joint Research Project of Zhejiang University with Zotye Automobile Corporation Limited on Si-Based Anode Materials(No.P-ZH-2018-003).
文摘Li-ion batteries(LIBs)have demonstrated great promise in electric vehicles and hybrid electric vehicles.However,commercial graphite materials,the current predominant anodes in LIBs,have a low theoretical capacity of only 372 mAh·g?1,which cannot meet the everincreasing demand of LIBs for high energy density.Nanoscale Si is considered an ideal form of Si for the fabrication of LIB anodes as Si–C composites.Synthesis of nanoscale Si in a facile,cost-effective way,however,still poses a great challenge.In this work,nanoscale Si was prepared by a controlled magnesiothermic reaction using diatomite as the Si source.It was found that the nanoscale Si prepared under optimized conditions(800°C,10 h)can deliver a high initial specific capacity(3053 mAh·g?1 on discharge,2519 mAh·g?1 on charge)with a high first coulombic efficiency(82.5%).When using sand-milled diatomite as a precursor,the obtained nanoscale Si exhibited a well-dispersed morphology and had a higher first coulombic efficiency(85.6%).The Si–C(Si:graphite=1:7 in weight)composite using Si from the sand-milled diatomite demonstrated a high specific capacity(over 700 mAh·g?1 at 100 mA·g?1),good rate capability(587 mAh·g?1 at 500 mA·g?1),and a long cycle life(480 mAh·g?1 after 200 cycles at 500 mA·g?1).This work gives a facile method to synthesize nanoscale Si with both high capacity and high first coulombic efficiency.
基金financially supported by the National Natural Science Foundation of China(Grant Nos.21965034,21703185,U1903217,51901013,and 21666037)the Xinjiang Autonomous Region Major Projects(2017A02004)+4 种基金the Leading Project Foundation of Science Department of Fujian Province(Grant No.2018H0034)the Resource Sharing Platform Construction Project of Xinjiang Province(PT1909)the Nature Science Foundation of Xinjiang Province(2017D01C074)the Opening Project of National Joint Engineering Research Center for Abrasion Control and Molding of Metal Materials,Henan University of Science and Technology(No.HKDNM201906)the Young Scholar Science Foundation of Xinjiang Educational Institutions(XJEDU2016S030)。
文摘Dramatic capacity fading and poor rate performance are two main obstacles that severely hamper the widespread application of the Si anode owing to its large volume variation during cycling and low intrinsic electrical conductivity.To mitigate these issues,free-standing N-doped porous carbon nanofibers sheathed pumpkin-like Si/C composites(Si/C-ZIF-8/CNFs)are designed and synthesized by electrospinning and carbonization methods,which present greatly enhanced electrochemical properties for lithium-ion battery anodes.This particular structure alleviates the volume variation,promotes the formation of stable solid electrolyte interphase(SEI)film,and improves the electrical conductivity.As a result,the as-obtained free-standing Si/C-ZIF-8/CNFs electrode delivers a high reversible capacity of 945.5 mAh g^(-1) at 0.2 A g^(-1) with a capacity retention of 64% for 150 cycles,and exhibits a reversible capacity of 538.6 mA h g^(-1) at 0.5 A g^(-1) over 500 cycles.Moreover,the full cell composed of a freestanding Si/C-ZIF-8/CNFs anode and commercial LiNi_(1/3)Co_(1/3)Mn_(1/3)O_(2)(NCM)cathode shows a capacity of 63.4 mA h g^(-1) after 100 cycles at 0.2 C,which corresponds to a capacity retention of 60%.This rational design could provide a new path for the development of high-performance Si-based anodes.
