Rational design of F,N-rich artificial interphase via chemical prelithiation initiation strategy enabling high coulombic efficiency and stable micro-sized SiO anodes

Silicon monoxide(SiO)is regarded as a potential candidate for anode materials of lithium-ion batteries(LIBs).Unfortunately,the application of SiO is limited by poor initial Coulombic efficiency(ICE)and unsteady solid electrolyte interface(SEI),which induce low energy,short cycling life,and poor rate properties.To address these drawbacks of SiO,we achieve in-situ construction of robust and fast-ion conducting F,N-rich SEI layer on prelithiated micro-sized SiO(P-μSiO)via the simple and continuous treatment ofμSiO in mild lithium 4,4′-dimethylbiphenyl solution and nonflammable hexafluorocyclotriphosphazene solution.Chemical prelithiation eliminates irreversible capacity through pre-forming inactive lithium silicates.Meanwhile,the symbiotic F,N-rich SEI with good mechanical stability and fast Li^(+)permeability is conductive to relieve volume expansion ofμSiO and boost the Li+diffusion kinetics.Consequently,the P-μSiO realizes an impressive electrochemical performance with an elevated ICE of 99.57%and a capacity retention of 90.67%after 350 cycles.Additionally,the full cell with P-μSiO anode and commercial LiFePO_(4) cathode displays an ICE of 92.03%and a high reversible capacity of 144.97 mA h g^(-1).This work offers a general construction strategy of robust and ionically conductive SEI for advanced LIBs.

基于聚碳酸丙烯酯基聚合物电解质和有机正极的全固态钠电池

聚碳酸酯具有较高的介电常数和较强极性的碳酸酯基团,是一类高性能的聚合物固态电解质,但是它在全固态钠离子电池体系中的研究非常少。本文以简便的方法成功制备出了聚碳酸丙烯酯基全固态聚合物电解质,并研究了该全固态电解质在以3,4,9,10-苝四甲酸二酐为正极的有机全固态钠电池中的应用。这种全固态聚合物电解质在钠离子电池中的应用能够有效提高钠离子电池的安全性,防止过充、电解液泄露甚至爆炸等一系列不安全因素带来的隐患。结果表明:这种聚碳酸丙烯酯基全固态聚合物电解质在室温下具有较高的电导率,并且循环前后的阻抗测试说明了该电解质与有机正极具有良好的兼容性。取代了传统液体有机电解液后,该全固态钠电池在室温下展示出了优异的循环性能,循环50周后,容量保持率为99.1%;然而,同类型的液体电池遭受了严重的容量衰减,循环50周后容量只有24.6 mAh·g^−1,容量保持率仅为20.5%。

不可燃氟代碳酸酯基钠离子电池电解液

锂离子电池由于其较高的能量密度而在我们的日常生活中被广泛使用,比如手机、笔记本电脑和电动汽车。然而,地球上有限的锂资源可能会阻碍其进一步的发展。近来,由于丰富的资源、合适的电化学平台和低廉的价格,钠离子电池正得到大家越来越多的关注,有希望成为下一代主流储能体系。然而,跟锂离子电池类似,钠离子电池的电解液主要是由易燃的有机碳酸酯或醚类溶剂、钠盐和一些添加剂组成,这就带来了安全隐患。此外,钠金属具有比锂更高的化学活性,导致钠离子电池可能具有比锂离子电池更大的危险性。为了解决这个安全性问题,我们提出一种不可燃的氟代碳酸酯基电解液。电解液成分是由0.9 mol·L^−1 NaPF6溶解在氟代碳酸乙烯酯(FEC)和二-2,2-三氟乙基碳酸酯(TFEC)(3:7,体积比)混合溶剂中组成。测试结果表明,该电解液体系不仅具有优异的阻燃能力,而且与钠离子电池的正负极都具有很好地相容性。在此电解液中,普鲁士蓝正极时表现出色的电化学性能,循环50圈后,仍有84 mAh·g^−1的容量。此外,商业化硬碳材料在该电解液中也表现出了较好的电化学性能。这项工作可能为开发下一代安全型钠离子电池提供新途径。

Self-assembled, highly-lithiophilic and well-aligned biomass engineered MXene paper enables dendrite-free lithium metal anode in carbonate-based electrolyte

Lithium metal anode is the ideal candidate for high-energy–density rechargeable batteries.However,uncontrolled dendrite growth hampers its commercialization.Herein,a dendrite-free composite Li metal anode is realized by a flexible,freestanding,well-aligned and highly-lithiophilic MXene paper designed by a facile electrostatic self-assembly of the exfoliated MXene nanosheets and natural polysaccharidechitosan (MX@CS).The MX@CS paper gets a well-aligned layered-3D structure with a micro-crumpled surface that can effectively decrease the local current density,guide even Li plating and suppress dendritic Li growth.More importantly,surface-adsorbed chitosan endows enhanced lithiophilicity for MXene substrate and thus reduces the Li nucleation overpotential,which is confirmed by the density functional theory calculations.Abundant lithiophilic groups on MX@CS surface provide highconcentration Li^(+)anchoring site promoting Li nucleation and laterally inducing uniform Li deposition,which effectively avoids the formation of dendritic Li.As a result,the MX@CS-Li anode with a dendrite-free Li morphology shows a significantly improved cycling life in commercial carbonatebased electrolyte.When coupled with LiNi_(0.8)Co_(0.1)Mn_(0.1)O_(2)cathode,the full cell exhibits a low capacity decay and steady ultrahigh Coulombic efficiency of 99.6%at a current density of 5C.These findings develop a new approach for designing high-performance metal-based rechargeable batteries.

Free-standing Na_(2)C_(6)O_(6)/MXene composite paper for highperformance organic sodium-ion batteries

Sodium-ion batteries(SIBs)are regarded as the ideal low-cost choice for next-generation large-scale energy storage system.Carbonyl-based organic salt-disodium rhodizonate(Na_(2)C_(6)O_(6))with high theoretical specific capacity(501 mAh·g−1)is considered as a promising cathode material for SIBs.However,the dissolution of active material in electrolyte and low electronic conductivity lead to rapidly capacity decay and poor rate performance.Herein,a simple method is designed to construct free-standing and flexible Ti3C2Tx Na2C6O6/MXene paper via vacuum-assisted filtration and antisolvent approach.The MXene can form an electronic conductive network,adsorb the active materials,and offer additional active sites for Na storage.The binder-free Na_(2)C_(6)O_(6)/MXene paper delivers excellent electrochemical property with a high rate performance of 231 mAh·g−1 at 1,000 mA·g−1 and a high capacity of 215 mAh·g−1 after 100 cycles.This work provides an attractive strategy for designing high-performance organic electrode materials of SIBs.

Flexible and stable 3D lithium metal anodes based on self-standing MXene/COF frameworks for high-performance lithium-sulfur batteries

Lithium metal(Li)is believed to be the ultimate anode for lithium-ion batteries(LIBs)owing to the advantages of high theoretical capacity,the lowest electrochemical potential,and light weight.Nevertheless,issues such as uncontrollable growth of Li dendrites,large volume changes,high chemical reactivity,and unstable solid electrolyte interphase(SEI)hinder its rapid development and practical application.Herein a stable and dendrite-free Li-metal anode is obtained by designing a flexible and freestanding MXene/COF framework for metallic Li.COF-LZU1 microspheres are distributed among the MXene film framework.Lithiophilic COF-LZU1 microspheres as nucleation seeds can promote uniform Li nucleation by homogenizing the Li^(+)flux and lowering the nucleation barrier,finally resulting in dense and dendrite-free Li deposition.Under the regulation of the COF-LZU1 seeds,the Coulombic efficiency of the MXene/COF-LZU1 framework and electrochemical stability of corresponding symmetric cells are obviously enhanced.Li-S full cells with the modified Li-metal anode and sulfurized polyacrylonitrile(S@PAN)cathode also exhibited a superior electrochemical performance.

Scalable construction of SiO/wrinkled MXene composite by a simple electrostatic self-assembly strategy as anode for high-energy lithium-ion batteries

Available onlineSilicon monoxide(SiO)is a promising anode material fo r lithium-ion batteries(LIBs)due to its high theoretical specific capacity(~2400 mAh/g),low working potential(<0.5 V vs.Li^+/Li),low cost,easy synthesis,nontoxicity,abundant natural source and smaller volume expansion than Si.However,low intrinsic electrical conductivity,low initial Coulombic efficiency(ICE)and inevitable volume expansion(~200%)impede its practical application.Here we fabricate SiO/wrinkled MXene composite(SiO-WM)by an electrostatic self-assembly method.Importantly,this method is simple,scalable and taking into account all the issues of SiO.As a result,the SiO-WM exhibits imp roved rate capability,cycling performance and ICE than bare SiO.

Room-temperature liquid metal engineered iron current collector enables stable and dendrite-free sodium metal batteries in carbonate electrolytes

Metallic sodium(Na)is believed to be a promising anode material for sodium-ion batteries(SIBs)due to its low electrochemical potential,high theoretical specific capacity,superior electrical conductivity,and so on.However,issues such as high chemical activity,the growth of Na dendrites,large volume change,and unstable interface impede its practical application.We design a cheap iron(Fe)-based substrate decorated by a thin liquid metal Ga layer for stable and dendrite-free Na metal anodes in low-cost carbonate electrolytes.The inherent mechanism of Ga-based liquid metal in inhibiting the growth of Na dendrites was revealed for the first time.Liquid metal Ga with sodiophilic property can act as nucleation seeds to decrease the nucleation barrier and induce homogeneous Na+flux,resulting in uniform and dendrite-free Na deposition.Full cells with Na_(3)V_(2)(PO_(4))_(3) cathode were also assembled to verify the practical application ability of the modified Na metal anode.Under the regulation of the liquid metal layer,the Coulombic efficiency,cycling life,and capacity of batteries are obviously enhanced.The strategy proposed here cannot only reduce the cost of batteries but also improve their electrochemical and safety performance.

Metal-organic frameworks and their derivatives in stable Zn metal anodes for aqueous Zn-ion batteries

Zn metal anode is believed to be a promising anode material for aqueous Zn-ion batteries(ZIBs)due to the mer-its such as low electrochemical potential,low cost,high theoretical specific capacity,high hydrogen evolution overpotential,less-reactive property,environmental friendliness and easy processing.However,issues including uncontrollable growth of Zn dendrites,corrosion by aqueous electrolyte,large volume change and unstable in-terface hinder its further development.Recently,multifunctional metal-organic frameworks(MOFs)and their derivatives have shown huge advantages in solving the issues facing Zn metal anode,and large advances have been achieved.MOFs and their derivatives can stabilize Zn metal anode by interface engineering,designing host,decorating separator,constructing solid-state electrolyte and so on.Here we carefully summarize and analyse these advances.Meanwhile,some perspectives and outlooks are put forward.This review can promote the de-velopment of MOFs,Zn metal anode as well as aqueous ZIBs.