A review of hard carbon anodes for rechargeable sodium-ion batteries

Hard carbons(HCs)are recognized as potential anode materials for sodium-ion batteries(SIBs)because of their low cost,environmental friendliness,and the abundance of their precursors.The presence of graphitic domains,numerous pores,and disordered carbon layers in HCs plays a significant role in determining their sodium storage ability,but these structural features depend on the precursor used.The influence of functional groups,including heteroatoms and oxygen-containing groups,and the microstructure of the precursor on the physical and electrochemical properties of the HC produced are evaluated,and the effects of carbonization conditions(carbonization temperature,heating rate and atmosphere)are also discussed.

Black Phosphorus/Nanocarbons Constructing a Dual-Carbon Conductive Network for High-Performance Sodium-Ion Batteries

Black phosphorus has been recognized as a prospective candidate anode material for sodium-ion batteries(SIBs)due to its ultrahigh theoretical capacity of 2596 mA·h/g and high electric conductivity of≈300 S/m.However,its large volume expansion and contraction during sodiation/desodiation lead to poor cycling stability.In this work,a BP/graphite nanoparticle/nitrogen-doped multiwalled carbon nanotubes(BP/G/CNTs)composite with a dual-carbon conductive network is successfully fabricated as a promising anode material for SIBs through a simple two-step mechanical milling process.The unique structure can mitigate the eff ect of volume changes and provide additional electron conduction pathways during cycles.Furthermore,the formation of P–O–C bonds helps maintain the intimate connection between phosphorus and carbon,thereby improving the cycling and rate performance.As a result,the BP/G/CNTs composite delivers a high initial Coulombic efficiency(89.6%)and a high specific capacity for SIBs(1791.3 mA·h/g after 100 cycles at 519.2 mA/g and 1665.2 mA·h/g after 100 cycles at 1298 mA/g).Based on these results,the integrated strategy of one-and two-dimensional carbon materials can guide other anode materials for SIBs.

Pyridine-regulated Sb@InSbS_(3)ultrafine nanoplates as high-capacity and long-cycle anodes for sodium-ion batteries

Sb-based materials exhibit considerable potential for sodium-ion storage owing to their high theoretica capacities.However,the bulk properties of Sb-based materials always result in poor cycling and rate performances.To overcome these issues,pyridine-regulated Sb@InSbS_(3)ultrafine nanoplates loaded on reduced graphene oxides(Sb@InSbS_(3)@rGO)were designed and synthesized.During the synthesis process,pyridine was initially adopted to coordinate with In^(3+),and uniformly dispersed In_(2)S_(3)ultrafine nanoplates on reduced graphene oxide were generated after sulfidation.Next,partial In^(3+)was exchanged with Sb^(3+),and Sb@InSbS_(3)@rGO was obtained by using the subsequent annealing method.The unique structure of Sb@InSbS_(3)@rGO effectively shortened the transfer path of sodium ions and electrons and provided a high pseudocapacitance.As the anode in sodium-ion batteries,the Sb@InSbS_(3)@rGO electrode demonstrated a significantly higher reversible capacity better stability(445 m Ah·g^(-1)at 0.1 A·g^(-1)after 200 cycles and 212 mAh·g^(-1)at 2 A·g^(-1)after 1200 cycles),and superior rate(210 mAh·g^(-1)at 6.4 A·g^(-1))than the electrode without pyridine(355 mAh·g-1at 0.1 A·g-1after 55 cycles and 109 mAh·g^(-1)at 2 A·g^(-1)after 770 cycles)Furthermore,full cells were assembled by using the Sb@InSbS_(3)@rGO as anode and Na_(3)V_(2)(PO_(4))_(3)as cathode which demonstrated good cycling and rate performances and exhibited promising application prospects.These results indicate that adjusting the microstructure of electrode materials through coordination balance is A·good strategy for obtaining high-capacity,high-rate,and longcycle sodium storage performances.

Phosphorus and phosphide nanomaterials for sodium-ion batteries

Sodium-ion batteries have received remarkable attention as next-generation high-performance electrochemical energy storage devices because of their cost effectiveness and the broad geographical distribution of sodium. As a critical component of sodium-ion batteries, anode materials, especially nanostructured anodes, have a significant effect on the electrochemical performance of sodium-ion batteries. Recent research indicates that phosphorus and metal phosphides show great promise as anode candidates for sodium-ion batteries because of their low cost and relatively high theoretical gravimetric and volumetric specific capacities. In this review, we systematically summarize recent research progress on state-of-the-art nanostructured phosphorus and phosphides, including the synthetic strategies, Na-storage mechanisms, and the relationship between the nanostructure and electrochemical performance. Moreover, we present an overview of future challenges and opportunities based on current developments.

Effects of Cr doping on structural and electrochemical properties of Li_(4)Ti_(5)O_(12) nanostructure for sodium-ion battery anode

Sodium-ion batteries are considered as promising alternatives to lithium-ion batteries,owing to their low cost and abundant raw materials.Among the several candidate materials for the anode,spinel-type Li_(4)Ti_(5)O_(12)has potential owing to its superior safety originating from an appropriate operating voltage and the reversible Na^(+)intercalation properties.However,a low diffusion coefficient for Na^(+)and the insulating nature of LTO remains challenging for practical sodium-ion battery systems.Herein,we present a strategy for integrating physical and chemical approaches to achieve superior electrochemical properties in LTO.We demonstrate that carefully controlling the amount of Cr doping is crucial to enhance the electrochemical properties of nanostructured LTO.Optimized Cr doped LTO shows a superior reversible capacity of 110 m Ah g^(-1) after 400 cycles at 1 C,with a three-fold higher capacity(75 m Ah g^(-1))at 10 C compared with undoped LTO material.This suggests that appropriately Cr doped nanostructured LTO is a promising anode material for sodium-ion batteries.

Nanostructured Na-ion and Li-ion anodes for battery application： A comparative overview

This paper offers a comprehensive overview on the role of nanostructures in the development of advanced anode materials for application in both lithium and sodium-ion batteries. In particular, this review highlights the differences between the two chemistries, the critical effect of nanosize on the electrode performance, as well as the routes to exploit the inherent potential of nanostructures to achieve high specific energy at the anode, enhance the rate capability, and obtain a long cycle life. Furthermore, it gives an overview of nanostructured sodium- and lithium-based anode materials, and presents a critical analysis of the advantages and issues associated with the use of nanotechnology.

B, N-Co-doped Carbon Tubes with P Encapsulated in 3D Graphene Aerogel for High-stable Lithium-ion Batteries

Li-related anodes with stable ability and excellent rate performance are urgently being pursued to overcome the slow kinetic of current lithium ion storage devices.In this work,an annealing-hydrothermal method is developed to fabricate the anode of a three-dimension nano-construction with robust charge transfer networks,which is composed of elements B,N co-doped carbon tube(BN-CT)as the carrier of red phosphorous to(3D BN-CT@P).Then,3D BN-CT@P is embedded in the graphene aerogel network to obtain (3D BN-CT@P@GA).Impressively,the 3D BN-CT@P@GA shows high capacity and good cycle stability in the potential rage of 0.01-2.5V.Especially,the discharge capacity is~800 mAh g^(-1) at 500 mA g^(-1) after 500 cycles when evaluated as anode materials for lithium-ion batteries(LIBs).The improved electrochemical performances result from the unique structure of the 3D BN-CT@P@GA.With the hetero atoms doping,the active P can load up to the BN-CT,which can realize the high capacity as well as the low potential for the anode.At the same time,the graphene aerogel network provides the protection for the BN-CT@P species and good conductivity to enhance ion diffusion.This work fundamentally presents an effective structural engineering way for improving the performance of P-based anodes for advanced LIBs.

Boosting sodium storage of mesoporous TiO2 nanostructure regulated by carbon quantum dots

It has been demonstrated that the conductivity and electrochemical properties of TiO2 nanomate rials can be significantly improved by an incorporation of carbon additives.In the study,we develop a novel Ndoped TiO2 mesoporous nanostructure via the addition of carbon quantum dots(CQDs)solution following a scalable hydrothermal process.The as-made TiO2 product shows well-defined morphology,high conductivity,large surface area,and abundant mesopores.When evaluated as anodes for sodiumion batteries,the CQDs@TiO2 product annealed at 500℃exhibits a superior sodium storage capability.It delivers a high reversible capacity of 168.8 mAh/g at 100 mA/g over 500 cycles and long cycling stability.The remarkable performance of CQDs@TiO2 mainly arises from the large surface area and mesoporous architecture constructed by ultrathin TiO2 nanosheets,as well as the full coope ration between CQDs and TiO2.

Universal architecture and defect engineering dual strategy for hierarchical antimony phosphate composite toward fast and durable sodium storage

Antimony(Sb)-ba sed anode materials are feasible candidates for sodium-ion batteries(SIBs) due to their high theoretical specific capacity and excellent electrical conductivity.However,they still suffer from volume distortion,structural collapse,and ionic conduction interruption upon cycling.Herein,a hierarchical array-like nanofiber structure was designed to address these limitations by combining architecture engineering and anion tuning strategy,in which SbPO_(4-x) with oxygen vacancy nanosheet arrays are anchored on the surface of interwoven carbon nanofibers(SbPO_(4-x)@CNFs).In particular,bulky PO_(4)^(3-) anions mitigate the large volume distortion and generate Na_(3)PO_(4) with high ionic conductivity,collectively improving cyclic stability and ionic transport efficiency.The abundant oxygen vacancies substantially boost the intrinsic electronic conductivity of SbPO_4,further accelerating the reaction dynamics.In addition,hierarchical fibrous structures provide abundant active sites,construct efficient conducting networks,and enhance the electron/ion transport capacity.Benefiting from the advanced structural design,the SbPO_(4-x)@CNFs electrodes exhibit outstanding cycling stability(1000 cycles at 1.0 A g^(-1) with capacity decay of 0.05% per cycle) and rapid sodium storage performance(293.8 mA h g^(-1) at 5.0 A g^(-1)).Importantly,systematic in-/ex-situ techniques have revealed the "multi-step conversion-alloying" reaction process and the "battery-capacitor dual-mode" sodium-storage mechanism.This work provides valuable insights into the design of anode materials for advanced SIBs with elevated stability and superior rate performance.

Phosphorus-doping and oxygen vacancy endowing anatase TiO_(2) with excellent sodium storage performance

Titanium dioxide is considered to be promising anode for sodium-ion batteries due to stable structure during the charge/discharge process.However,its practical application is hindered by the slow electron/ion transport.Herein,phosphorus-doped anatase TiO_(2) nanoparticles with oxygen vacancies are successfully synthesized and utilized as high-performance sodium-storage materials.The dual strategy of phosphorus-doping and oxygen vacancies can concurrently boost electronic conductivity and adjust ion diffusion kinetics.They significantly contribute to the improved rate performance(167 mAh·g^(-1) at 20.0C)and stable cycling(95.9%after 2000 cycles at 20.0C).The proposed dual strategy can be potentially used to improve other oxide anodes for rechargeable batteries.

High-performance sodium storage for cobalt phosphide composite array electrodes

Transition metal phosphides hold great potential as sodium-ion batteries anode materials owing to their high theoretical capacity and modest plateau.However,volume changes and low intrinsic conductivity seriously largely hinder the further development of metal phosphide anodes.The design of phosphide anode materials with reasonable structure is conducive to solving the problems of volume expansion and slow reaction kinetics during the reaction.In this work,a composite material integrating zeolite imidazolate backbone(ZIF) and carbon materials was synthesized by the original growth method.Furthermore,by the oxidation-phosphating process,CoP nanoarray composites riveted to carbon fiber(CoP@CF) were obtained.In the CoP@CF,CoP nanoparticles are uniformly distributed on ZIF-derived carbon,reducing agglomeration and volume change during cycling.CF also provides a highly conductive network for the active material,improving the electrode kinetics.Therefore,when evaluated as an anode for sodium-ion batteries,CoP@CF electrode displays enhanced reversible capacity(262 mAh·g^(-1) at 0.1 A·g^(-1)after 100 cycles),which is much better than that of pure CF electrode(57 mAh·g^(-1) at 0.1 A·g^(-1) after 100 cycles)prepared without the addition of CoP.The rate performance of CoP@CF electrode is also superior to that of pure CF electrode at various current densities from 0.05 to1 A·g^(-1).The sodium storage behavior of CoP@CF was revealed by ex-situ X-ray photoelectron spectroscopy,X-ray diffraction,and synchrotron radiation absorption spectroscopy.This method provides a reference for the design and synthesis of anode materials in sodium-ion batteries.

Ultrafine Sn_(4)P_(3)nanocrystals from chloride reduction on mechanically activated Na surface for sodium/lithium ion batteries

Nanostructured metal phosphides are very attractive materials in energy storage and conversion,but their applications are severely limited by complicated preparation steps,harsh conditions and large excess of highly toxic phosphorus source.Here we develop a highly efficient one-step method to synthesize Sn_(4)P_(3)nanostructure based on simultaneous reduction of SnCl_(4)and PCl_(3)on mechanically activated Na surface and in situ phosphorization.The low-toxic PCl3 displays a very high phosphorizing efficiency(100%).Furthermore,this simple method is powerful to control phosphide size.Ultrafine Sn_(4)P_(3)nanocrystals(<5 nm)supported on carbon sheets(Sn_(4)P_(3)/C)are obtained,which is due to the unique bottom-up surface-limited reaction.As the anode material for sodium/lithium ion batteries(SIBs/LIBs),the Sn_(4)P_(3)/C shows profound sodiation/lithiation extents,good phase-conversion reversibility,excellent rate performance and long cycling stability,retaining high capacities of 420 mAh/g for SIBs and 760 mAh/g for LIBs even after 400 cycles at 1.0 A/g.Combining simple and efficient preparation,low-toxic and high-efficiency phosphorus source and good control of nanosize,this method is very promising for low-cost and scalable preparation of high-performance Sn_(4)P_(3)anode.

自模板法构筑中空纳米结构CoP-C复合微球及其电化学储钠性能

过渡金属磷化物因具有合适的电压平台和较大的理论容量,是一种理想的钠离子电池负极材料。然而,由于过渡金属磷化物导电性差且与钠离子反应过程中体积膨胀严重,导致其倍率和循环性能较差。本研究以磷化钴为研究对象,采用自牺牲模板法,以钴-甘油微米球(Co-gly)为前驱体,通过气相磷化法构筑了中空纳米结构CoP-C复合微球(CoP-C HS)。通过XRD、SEM、TEM和HRTEM等分析技术对所制备的材料进行了结构表征。将该材料用作钠离子电池负极材料时,相较块状CoP,CoP-C HS的储钠性能得到显著提升:在200 mA·g^(-1)的电流密度下循环1000圈后比容量仍然保持在112 mAh·g^(-1);在1 A·g^(-1)的大电流密度下可逆充放电容量达到了126 mAh·g^(-1)。中空纳米结构为电化学反应提供了更多活性位点并能够有效缓解脱钠/嵌钠过程中的体积膨胀,而与碳复合能提高材料的导电性并有效抑制材料循环过程中的结构破坏。