Breaking Mass Transport Limitations by Iodized Polyacrylonitrile Anodes for Extremely Fast-Charging Lithium-Ion Batteries

The fast-charging capability of rechargeable batteries is greatly limited by the sluggish ion transport kinetics in anode materials. Here we develop an iodized polyacrylonitrile (I-PAN) anode that can boost the bulk/interphase lithium (Li)-ion diffusion kinetics and accelerate Li-ion desolvation process to realize high-performance fast-charging Li-ion batteries. The iodine immobilized in I-PAN framework expands ion transport channels, compresses the electric double layer, and changes the inner Helmholtz plane to form LiF/LiI-rich solid electrolyte interphase layer. The dissolved iodine ions in the electrolyte self-induced by the interfacial nucleophilic substitution of PF₆⁻ not only promote the Li-ion desolvation process, but also reuse the plated/dead Li formed on the anode under fast-charging conditions. Consequently, the I-PAN anode exhibits a high capacity of 228.5 mAh g⁻¹ (39 % of capacity at 0.5 A g⁻¹ delivered in 18 seconds) and negligible capacity decay for 10000 cycles at 20 A g⁻¹. The I-PAN||LiNi_0.8Co_0.1Mn_0.1O₂ full cell shows excellent fast-charging performance with attractive capacities and negligible capacity decay for 1000 cycles at extremely high rates of 5 C and 10 C (1 C=180 mA g⁻¹). We also demonstrate high-performance fast-charging sodium-ion batteries using I-PAN anodes.     

Rechargeable Sodium-Ion Battery Based on Polyazaacene Analogue Anode

The high theoretical specific capacity, strong structural designability and relatively inexpensive manufacturing cost make the exploration of organic electrode materials more attractive in recent years. In this article, owing to the large π-conjugated structure, plenty of nitrogen heteroatoms and multiring aromatic system, polyazaacene analogue poly(1,6-dihydropyrazino[2,3 g]quinoxaline-2,3,8-triyl-7-(2H)-ylidene-7,8-dimethylidene) (PQL) was applied as the anode in sodium-ion batteries (SIBs). PQL was almost insoluble in conventional liquid organic electrolyte (1 M NaClO₄ in ethylene carbonate (EC)/dimethyl carbonate (DMC) (v:v=1 : 1) with 5 % fluoroethylene carbonate (FEC)), which strongly improved its cycle stability. The initial discharge capacity was obtained to be 1825 mAh g⁻¹ at the current density of 100 mA g⁻¹ and stabilized at 317 mAh g⁻¹ after 400 cycles with the coulombic efficiency as high as 97 %. It not only showed good rate capability at high current densities (202, 183 mAh g⁻¹ at 1 A g⁻¹ and 1.5 A g⁻¹) but also had a superior energy density around 290 Wh kg⁻¹.     

Facile Synthesis of Ultra-Small Few-Layer Nanostructured MoSe2 Embedded on N,P Co-Doped Bio-Carbon for High-Performance Half/Full Sodium-Ion and Potassium-Ion Batteries

Sodium/potassium-ion batteries (SIBs/PIBs) arouse intensive interest on account of the natural abundance of sodium/potassium resources, the competitive cost and appropriate redox potential. Nevertheless, the huge challenge for SIBs/PIBs lies in the scarcity of an anode material with high capacity and stable structure, which are capable of accommodating large-size ions during cycling. Furthermore, using sustainable natural biomass to fabricate electrodes for energy storage applications is a hot topic. Herein, an ultra-small few-layer nanostructured MoSe₂ embedded on N, P co-doped bio-carbon is reported, which is synthesized by using chlorella as the adsorbent and precursor. As a consequence, the MoSe₂/NP-C-2 composite represents exceedingly impressive electrochemical performance for both sodium-ion batteries (SIBs) and potassium-ion batteries (PIBs). It displays a promising reversible capacity (523 mAh g⁻¹ at 100 mA g⁻¹ after 100 cycles) and impressive long-term cycling performance (192 mAh g⁻¹ at 5 A g⁻¹ even after 1000 cycles) in SIBs, which are some of the best properties of MoSe₂-based anode materials for SIBs to date. To further probe the great potential applications, full SIBs pairing the MoSe₂/NP-C-2 composite anode with a Na₃V₂(PO₄)₃ cathode also exhibits a satisfactory capacity of 215 mAh g⁻¹ at 500 mA g⁻¹ after 100 cycles. Moreover, it also delivers a decent reversible capacity of 131 mAh g⁻¹ at 1 A g⁻¹ even after 250 cycles for PIBs.     

Designing Solvated Double-Layer Polymer Electrolytes with Molecular Interactions Mediated Stable Interfaces for Sodium Ion Batteries

Unstable cathode-electrolyte and/or anode-electrolyte interface in polymer-based sodium-ion batteries (SIBs) will deteriorate their cycle performance. Herein, a unique solvated double-layer quasi-solid polymer electrolyte (SDL-QSPE) with high Na⁺ ion conductivity is designed to simultaneously improve stability on both cathode and anode sides. Different functional fillers are solvated with plasticizers to improve Na⁺ conductivity and thermal stability. The SDL-QSPE is laminated by cathode- and anode-facing polymer electrolyte to meet the independent interfacial requirements of the two electrodes. The interfacial evolution is elucidated by theoretical calculations and 3D X-ray microtomography analysis. The Na_0.67Mn_2/3Ni_1/3O₂|SDL-QSPE|Na batteries exhibit 80.4 mAh g⁻¹ after 400 cycles at 1 C with the Coulombic efficiency close to 100 %, which significantly outperforms those batteries using the monolayer-structured QSPE.     

In Situ Nitrogen Retention of Carbon Anode for Enhancing the Electrochemical Performance for Sodium-Ion Battery

Retaining nitrogen for polyacrylonitrile (PAN) based carbon anode is a cost-effective way to make full use of the advantages of PAN for sodium-ion batteries (SIBs). Here, a simple strategy has been successfully adopted to retain N atoms in situ and increase production yield of a novel composite PAZ by mixing 3 wt % of zinc borate (ZB) with poly (acrylonitrile-co-itaconic acid) (PANIA). Among the prepared carbonised fibre (CF) samples, PAZ-CF-700 maintains the highest N content, retaining 90 % of the original N from PANIA. It represents the highest capacity storage contribution (80.55 %) and the lowest impedance R_ct (117 Ω). Consequently, the specific capacity increases from 60 mAh g⁻¹ of PANIA-CF-700 to 190 mAh g⁻¹ of PAZ-CF-700 at a current density of 100 mA g⁻¹. At the same time, PAZ-CF-700 exhibits a good rate performance and excellent long-term cycling stability with a specific capacity of 94 mAh g⁻¹ after 4000 cycles at 1.6 A g⁻¹.     

Enhanced electrochemical performance of carbon-coated TiO2 nanobarbed fibers as anode material for lithium-ion batteries

We report the electrochemical performance of carbon-coated TiO₂ nanobarbed fibers (TiO₂@C NBFs) as anode material for lithium-ion batteries. The TiO₂@C NBFs are composed of TiO₂ nanorods grown on TiO₂ nanofibers as a core, coated with a carbon shell. These nanostructures form a conductive network showing high capacity and C-rate performance due to fast lithium-ion diffusion and effective electron transfer. The TiO₂@C NBFs show a specific reversible capacity of approximately 170 mAh g^− 1 after 200 cycles at a 0.5 A g^− 1 current density, and exhibit a discharge rate capability of 4 A g^− 1 while retaining a capacity of about 70 mAh g^− 1. The uniformly coated amorphous carbon layer plays an important role to improve the electrical conductivity during the lithiation–delithiation process.     

Organic pH Buffer for Dendrite-Free and Shuttle-Free Zn-I2 Batteries

Aqueous Zn-Iodine (I₂) batteries are attractive for large-scale energy storage. However, drawbacks include, Zn dendrites, hydrogen evolution reaction (HER), corrosion and, cathode “shuttle” of polyiodines. Here we report a class of N-containing heterocyclic compounds as organic pH buffers to obviate these. We evidence that addition of pyridine /imidazole regulates electrolyte pH, and inhibits HER and anode corrosion. In addition, pyridine and imidazole preferentially absorb on Zn metal, regulating non-dendritic Zn plating /stripping, and achieving a high Coulombic efficiency of 99.6 % and long-term cycling stability of 3200 h at 2 mA cm⁻², 2 mAh cm⁻². It is also confirmed that pyridine inhibits polyiodines shuttling and boosts conversion kinetics for I⁻/I₂. As a result, the Zn-I₂ full battery exhibits long cycle stability of >25 000 cycles and high specific capacity of 105.5 mAh g⁻¹ at 10 A g⁻¹. We conclude organic pH buffer engineering is practical for dendrite-free and shuttle-free Zn-I₂ batteries.     

Low-Temperature Synthesis of Honeycomb CuP2@C in Molten ZnCl2 Salt for High-Performance Lithium Ion Batteries

Phosphorus-rich metal phosphides have very high lithium storage capacities, but they are difficult to prepare. A low-temperature phosphorization method based on Mg reducing PCl₃ in ZnCl₂ molten salt at 300 °C is developed to synthesize phosphorus-rich CuP₂@C from a Cu-MOF derived Cu@C composite. Abnormal oxidation of Cu by Zn²⁺ in the molten salt is observed, which leads to the porous honeycomb nanostructure and homogeneously distributed ultrafine CuP₂ nanocrystals. The honeycomb CuP₂@C exhibits excellent lithium storage performance with high reversible capacity (1146 mAh g⁻¹ at 0.2 A g⁻¹) and superior cycling stability (720 mAh g⁻¹ after 600 cycles at 1.0 A g⁻¹), showing the promising application of P-rich metal phosphides in lithium ion batteries.     

Solution Synthesis of Porous Silicon Particles as an Anode Material for Lithium Ion Batteries

Nanostructured silicon-based materials with porous structures have recently been found to be impressive anode materials with high capacity and cycling performance for lithium-ion batteries. However, the current methods of preparing porous silicon have generally been confronted with the requirement for multiple steps and complex synthesis. In the present study, porous silicon with high surface area was prepared by using a high yielding and simple reaction in which commercial magnesium powder readily reacts with HSiCl₃ with the help of an amine catalyst under mild conditions. The obtained porous silicon was coated with a nitrogen-doped carbon layer and used as the anode for lithium-ion batteries. The porous Si-carbon nanocomposites exhibited excellent cycling performance with a retained discharge capacity of 1300 mA h g⁻¹ after 200 cycles at 1 A g⁻¹ and a discharge capacity of 750 mA h g⁻¹ at a current density of 2 A g⁻¹ after 250 cycles. Remarkably, the Coulombic efficiency was maintained at nearly 100 % throughout the measurements.     

Scalable Synthesis of Porous SiFe@C Composite with Excellent Lithium Storage

Utilizing cost-effective raw materials to prepare high-performance silicon-based anode materials for lithium-ion batteries (LIBs) is both challenging and attractive. Herein, a porous SiFe@C (pSiFe@C) composite derived from low-cost ferrosilicon is prepared via a scalable three-step procedure, including ball milling, partial etching, and carbon layer coating. The pSiFe@C material integrates the advantages of the mesoporous structure, the partially retained FeSi₂ conductive phase, and a uniform carbon layer (12–16 nm), which can substantially alleviate the huge volume expansion effect in the repeated lithium-ion insertion/extraction processes, effectively stabilizing the solid–electrolyte interphase (SEI) film and markedly enhancing the overall electronic conductivity of the material. Benefiting from the rational structure, the obtained pSiFe@C hybrid material delivers a reversible capacity of 1162.1 mAh g⁻¹ after 200 cycles at 500 mA g⁻¹, with a higher initial coulombic efficiency of 82.30 %. In addition, it shows large discharge capacities of 803.1 and 600.0 mAh g⁻¹ after 500 cycles at 2 and 4 A g⁻¹, respectively, manifesting an excellent electrochemical lithium storage. This work provides a good prospect for the commercial production of silicon-based anode materials for LIBs with a high lithium-storage capacity.     

Electrostatic Shielding Boosts Electrochemical Performance of Alloy-Type Anode Materials of Sodium-Ion Batteries

The applications of alloy-type anode materials for Na-ion batteries are always obstructed by enormous volume variation upon cycles. Here, K⁺ ions are introduced as an electrolyte additive to improve the electrochemical performance via electrostatic shielding, using Sn microparticles (μ-Sn) as a model. Theoretical calculations and experimental results indicate that K⁺ ions are not incorporated in the electrode, but accumulate on some sites. This accumulation slows down the local sodiation at the “hot spots”, promotes the uniform sodiation and enhances the electrode stability. Therefore, the electrode maintains a high specific capacity of 565 mAh g⁻¹ after 3000 cycles at 2 A g⁻¹, much better than the case without K⁺. The electrode also remains an areal capacity of ≈3.5 mAh cm⁻² after 100 cycles. This method does not involve time-consuming preparation, sophisticated instruments and expensive reagents, exhibiting the promising potential for other anode materials.     

A Multi-Wall Sn/SnO2@Carbon Hollow Nanofiber Anode Material for High-Rate and Long-Life Lithium-Ion Batteries

Multi-wall Sn/SnO₂@carbon hollow nanofibers evolved from SnO₂ nanofibers are designed and programable synthesized by electrospinning, polypyrrole coating, and annealing reduction. The synthesized hollow nanofibers have a special wire-in-double-wall-tube structure with larger specific surface area and abundant inner spaces, which can provide effective contacting area of electrolyte with electrode materials and more active sites for redox reaction. It shows excellent cycling stability by virtue of effectively alleviating pulverization of tin-based electrode materials caused by volume expansion. Even after 2000 cycles, the wire-in-double-wall-tube Sn/SnO₂@carbon nanofibers exhibit a high specific capacity of 986.3 mAh g⁻¹ (1 A g⁻¹) and still maintains 508.2 mAh g⁻¹ at high current density of 5 A g⁻¹. This outstanding electrochemical performance suggests the multi-wall Sn/SnO₂@ carbon hollow nanofibers are great promising for high performance energy storage systems.     

Improving Low-temperature Performance and Stability of Na2Ti6O13 Anodes by the Ti−O Spring Effect through Nb-doping

Na₂Ti₆O₁₃ (NTO) with high safety has been regarded as a promising anode candidate for sodium-ion batteries. In the present study, integrated modification of migration channels broadening, charge density re-distribution, and oxygen vacancies regulation are realized in case of Nb-doping and have obtained significantly enhanced cycling performance with 92 % reversible capacity retained after 3000 cycles at 3000 mA g⁻¹. Moreover, unexpected low-temperature performance with a high discharge capacity of 143 mAh g⁻¹ at 100 mA g⁻¹ under −15 °C is also achieved in the full cell. Theoretical investigation suggests that Nb preferentially replaces Ti3 sites, which effectively improves structural stability and lowers the diffusion energy barrier. What's more important, both the in situ X-ray diffraction (XRD) and in situ Raman furtherly confirm the robust spring effect of the Ti−O bond, making special charge compensation mechanism and respective regulation strategy to conquer the sluggish transport kinetics and low conductivity, which plays a key role in promoting electrochemical performance.     

Zincophilic Electrode Interphase with Appended Proton Reservoir Ability Stabilizes Zn Metal Anodes

The rampant dendrites and hydrogen evolution reaction (HER) resulting from the turbulent interfacial evolution at the anode/electrolyte are the main culprits of short lifespan and low Coulombic efficiency of Zn metal batteries. In this work, a versatile protective coating with excellent zincophilic and amphoteric features is constructed on the surface of Zn metal (ZP@Zn) as dendrite-free anodes. This kind of protective coating possesses the advantages of reversible proton storage and rapid desolvation kinetics, thereby mitigating the HER and facilitating homogeneous nucleation concomitantly. Furthermore, the space charge polarization effect promotes charge redistribution to achieve uniform Zn deposition. Accordingly, the ZP@Zn symmetric cell manifests excellent reversibility at an ultrahigh cumulative plating capacity of 4700 mAh cm⁻² and stable cycling at 80 % depth of discharge (DOD). The ZP@Zn//V₆O₁₃ pouch cell also reveals superior cycling stability with a high capacity of 326.6 mAh g⁻¹.     

锂离子电池高比容量FeSn2-C复合负极材料的合成与性能

Sn基合金负极材料具有高达990 mAh·g^-1的理论比容量,但其也存在因脱嵌锂过程发生巨大的体积变化而导致循环性能较差的问题. 本文以Sn、Fe、石墨为原料利用简易的高能球磨法成功制备了具有核壳结构的FeSn₂-C复合物,系统研究了球磨时间、FeSn₂相含量对材料物相结构及电化学性能的影响,并分析了电极的失效机理. 研究表明,球磨时间的增加有利于FeSn₂金属间化合物相的形成及材料颗粒的细化,进而有利于材料比容量的增加及循环性能的提升;FeSn₂相含量的增加能够提高FeSn₂-C材料的比容量,但会降低FeSn₂-C电极的循环稳定性. 经工艺优化及组分调节,球磨24 h合成的Sn₂₀Fe₁₀C₇₀材料具有最优的电化学性能,材料的比容量在540 mAh·g^-1左右,并能稳定循环100次,是一种非常有发展前途的锂离子电池高比容量负极材料.     

Two-Dimensional Germanium Sulfide Nanosheets as an Ultra-Stable and High Capacity Anode for Lithium Ion Batteries

Lithium ion batteries (LIBs) at present still suffer from low rate capability and poor cycle life during fast ion insertion/extraction processes. Searching for high-capacity and stable anode materials is still an ongoing challenge. Herein, a facile strategy for the synthesis of ultrathin GeS₂ nanosheets with the thickness of 1.1 nm is reported. When used as anodes for LIBs, the two-dimensional (2D) structure can effectively increase the electrode/electrolyte interface area, facilitate the ion transport, and buffer the volume expansion. Benefiting from these merits, the as-synthesized GeS₂ nanosheets deliver high specific capacity (1335 mAh g⁻¹ at 0.15 A g⁻¹), extraordinary rate performance (337 mAh g⁻¹ at 15 A g⁻¹) and stable cycling performance (974 mAh g⁻¹ after 200 cycles at 0.5 A g⁻¹). Importantly, our fabricated Li-ion full cells manifest an impressive specific capacity of 577 mAh g⁻¹ after 50 cycles at 0.1 A g⁻¹ and a high energy density of 361 Wh kg⁻¹ at a power density of 346 W kg⁻¹. Furthermore, the electrochemical reaction mechanism is investigated by the means of ex-situ high-resolution transmission electron microscopy. These results suggest that GeS₂ can use to be an alternative anode material and encourage more efforts to develop other high-performance LIBs anodes.     

Carbonyl-rich Poly(pyrene-4,5,9,10-tetraone Sulfide) as Anode Materials for High-Performance Li and Na-Ion Batteries

Organic carbonyl electrode materials are widely employed for alkali metal-ion secondary batteries in terms of their sustainability, structure designability and abundant resources. As a typical redox-active organic electrode materials, pyrene-4, 5, 9, 10-tetraone (PT) shows high theoretical capacity due to the rich carbonyl active sites. But its electrochemical behavior in secondary batteries still needs further exploration. Herein, PT-based linear polymers (PPTS) is synthesized with thioether bond as bridging group and then employed as an anode material for lithium-ion batteries (LIBs) and sodium-ion batteries (SIBs). As expected, PPTS shows improved conductivity and insolubility in the non-aqueous electrolyte. When used as an anode material for LIBs, PPTS delivers a high reversible specific capacity of 697.1 mAh g⁻¹ at 0.1 A g⁻¹ and good rate performance (335.4 mAh g⁻¹ at 1 A g⁻¹). Moreover, a reversible specific capacity of 205.2 mAh g⁻¹ at 0.05 A g⁻¹ could be obtained as an anode material for SIBs.     

A Covalent Organic Framework as a Long-life and High-Rate Anode Suitable for Both Aqueous Acidic and Alkaline Batteries

Aqueous rechargeable batteries are prospective candidates for large-scale grid energy storage. However, traditional anode materials applied lack acid-alkali co-tolerance. Herein, we report a covalent organic framework containing pyrazine (C=N) and phenylimino (−NH−) groups (HPP-COF) as a long-cycle and high-rate anode for both acidic and alkaline batteries. The HPP-COF′s robust covalent linkage and the hydrogen bond network between −NH− and water molecules collectively improve the acid-alkaline co-tolerance. More importantly, the hydrogen bond network promotes the rapid transport of H⁺/OH⁻ by the Grotthuss mechanism. As a result, the HPP-COF delivers a superior capacity and cycle stability (66.6 mAh g⁻¹@ 30 A g⁻¹, over 40000 cycles in 1 M H₂SO₄ electrolyte; 91.7 mAh g⁻¹@ 100 A g⁻¹, over 30000 cycles @ 30 A g⁻¹ in 1 M NaOH electrolyte). The work opens a new direction for the structural design and application of COF materials in acidic and alkaline batteries.     

Sulfur-/Nitrogen-Rich Albumen Derived “Self-Doping” Graphene for Sodium-Ion Storage

The development of sodium-ion batteries (SIBs) is hindered by the rapid reduction in reversible capacity of carbon-based anode materials. Outside-in doping of carbon-based anodes has been extensively explored. Nickel and NiS₂ particles embedded in nitrogen and sulfur codoped porous graphene can significantly improve the electrochemical performance. Herein a built-in heteroatom “self-doping” of albumen-derived graphene for sodium storage is reported. The built-in sulfur and nitrogen in albumen act as the doping source during the carbonization of proteins. The sulfur-rich proteins in albumen can also guide the doping and nucleation of nickel sulfide nanoparticles. Additionally, the porous architecture of the carbonized proteins is achieved through removable KCl/NaCl salts (medium) under high-temperature melting conditions. During the carbonization process, nitrogen can also reduce the carbonization temperature of thermally stable carbon materials. In this work, the NS-graphene delivered a specific capacity of 108.3 mAh g⁻¹ after 800 cycles under a constant current density of 500 mA g⁻¹. In contrast, the Ni/NiS₂/NS-graphene maintained a specific capacity of 134.4 mAh g⁻¹; thus the presence of Ni/NiS₂ particles improved the electrochemical performance of the whole composite.     

Hierarchical Hollow-Nanocube Ni−Co Skeleton@MoO3/MoS2 Hybrids for Improved-Performance Lithium-Ion Batteries

Improving the performance of anode materials for lithium-ion batteries (LIBs) is a hotly debated topic. Herein, hollow Ni−Co skeleton@MoS₂/MoO₃ nanocubes (NCM-NCs), with an average size of about 193 nm, have been synthesized through a facile hydrothermal reaction. Specifically, MoO₃/MoS₂ composites are grown on Ni−Co skeletons derived from nickel–cobalt Prussian blue analogue nanocubes (Ni−Co PBAs). The Ni−Co PBAs were synthesized through a precipitation method and utilized as self-templates that provided a larger specific surface area for the adhesion of MoO₃/MoS₂ composites. According to Raman spectroscopy results, as-obtained defect-rich MoS₂ is confirmed to be a metallic 1T-phase MoS₂. Furthermore, the average particle size of Ni−Co PBAs (≈43 nm) is only about one-tenth of the previously reported particle size (≈400 nm). If assessed as anodes of LIBs, the hollow NCM-NC hybrids deliver an excellent rate performance and superior cycling performance (with an initial discharge capacity of 1526.3 mAh g⁻¹ and up to 1720.6 mAh g⁻¹ after 317 cycles under a current density of 0.2 A g⁻¹). Meanwhile, ultralong cycling life is retained, even at high current densities (776.6 mAh g⁻¹ at 2 A g⁻¹ after 700 cycles and 584.8 mAh g⁻¹ at 5 A g⁻¹ after 800 cycles). Moreover, at a rate of 1 A g⁻¹, the average specific capacity is maintained at 661 mAh g⁻¹. Thus, the hierarchical hollow NCM-NC hybrids with excellent electrochemical performance are a promising anode material for LIBs.