Prolonged Cycle Life Research Articles

Exploiting Iodine Redox Chemistry for Achieving High‐Capacity and Durable PEO‐Based All‐Solid‐State LiFePO4/Li Batteries

AbstractPoly (ethylene oxide) (PEO)‐based electrolytes are extensively applied to LiFePO4/Li solid‐state batteries on account of their high safety and good flexibility. Nevertheless, the unsatisfactory energy density and inferior lifespan of the batteries still inhibit their large‐scale applications. Herein, graphitic carbon nitride nanosheets (GCN)‐assisted‐alkali metal iodides are proposed as multifunctional fillers for PEO‐based electrolytes. GCN is introduced to fix the location of iodine species through adsorption to reduce iodine migration and promote the kinetics of iodine redox reactions. Besides reducing the PEO crystallinity and elevating the ionic conductivity of electrolyte, the incorporation of GCN‐assisted‐alkali metal iodides facilitates lithium migration, constructs a stable interphase on the Li anode, and enables uniform deposition of lithium. Of particular note, extra capacity is provided through iodine redox reactions. The all‐solid‐state LiFePO4/Li battery using GCN‐LiI modified PEO electrolyte (GCN‐LiI‐PEO) delivers a high discharge capacity of 228.4 mAh g−1 at 0.1 C. Superior rate capability with 99.2 mAh g−1 at 10 C and high‐capacity retention of 87.3% after 900 cycles at 0.5 C are also achieved. Moreover, the LiFePO4/Li batteries using GCN‐assisted‐KI or NaI also achieve high capacity and prolonged cycle life. This work opens a promising avenue for pursuing high‐energy density solid‐state batteries.

A high-performance zinc anode enabled by carbon quantum dots with H2O-structure-regulating capabilities

Aqueous Zn metal batteries offer high specific capacity and adequate safety, but suffer from limited stability and longevity primarily due to interfacial H2O-induced parasitic reactions on Zn anode. It thus is imperative to understand and control the interfacial H2O behavior for enhancing electrochemical performance of Zn anode. Herein, we formulate a functional aqueous Zn2+ electrolyte, containing well-dispersed Zn-doped carbon quantum dots (ZCDs) that can dynamically self-enrich on the Zn anode surface and thus endowed with unique interfacial “H2O-structure-regulating” capabilities. The Zn anode in contact with this exotic electrolyte demonstrates an essentially dendrite-free plating/stripping process, a 64.1% HER inhibition efficiency, a substantially prolonged cycle life (over 1500 h at 5 mA cm−2), an exceptional cumulative capacity of ∼3.75 Ah cm−2, and a capacity retention of a Zn||V2O5 battery up to ∼83% over 4000 cycles. A mechanistic study, using a combination of in situ spectroscopies and density functional theory calculations, provides direct spectroscopic evidence that the enriched ZCDs on the Zn surface reduce the proportion of reactive solvated H2O and thereof suppresses the H2O-induced parasitic reactions. The results reported here underscore the crucial significance of regulating the interfacial H2O structures on Zn2+ deposition process, and also provide inspirational design criteria for better Zn-based energy conversion and storage devices.

Combining Solid Solution Strengthening and Second Phase Strengthening for Thinning Li Metal Foils.

Thin lithium (Li) metal foils have been proved to be indispensable yet elusive for practical high-energy-density lithium batteries. Currently, the realization of such thin foils (<50 μm) is impeded by the inferior mechanical processability of metallic Li. In this work, we demonstrate that the combination of solid solution strengthening and second phase strengthening, achieved by the addition of silver fluoride (AgF) to Li metal, can substantially enhance both the strength and ductility of metallic Li. Benefiting from the improved machinability, we succeed in fabricating an ultrathin (down to 5 μm), freestanding, and mechanically robust Li-AgF composite foil. More interestingly, the in situ-formed LixAg-LiF skeleton in the composite facilitates Li diffusion kinetics and uniform Li deposition, where the thin Li-AgF electrode displays a prolonged cycle life over 500 h at 1 mA cm-2 and 1 mAh cm-2 in a carbonate electrolyte. Coupled with a commercial LiCoO2 cathode (3.4 mAh cm-2), the LiCoO2||Li-AgF cell delivers a notable capacity retention of ∼90% over 100 cycles at 0.5 C with a low negative/positive ratio of 2.5.

Modulating electronic structure with heteroatom dopants in porous hard carbon towards ultralong lifespan sodium-ion batteries

Hard carbon (HC) has been recognized as one of the most mature and commercialized anode materials for sodium-ion batteries (SIBs). However, it still faces problems such as low reversible capacity, poor rate capability and cycling stability for commercial applications. Herein, we propose a systematic investigation into heteroatom-doped engineering for tailoring the electronic structure of N-doped carbon by integrating heterogeneous atoms (S/P) into 3-dimensional (3D) interconnected porous HC. Thus-fabricated N/P dual-doped HC (NPDC) exhibits improved electronic conductivity and expanded interlayer spacing, which endows high rate capability and prolonged cycle life over 28,000cycles for SIBs (1400 h lifespan at 5.0 A/g). Theoretical and experimental results unravel that the electron-donating ability of P atoms with unmatched p orbital slightly change the spin density optimizes the adsorption energy and electronic structure to balance the Na+ adsorption/intercalation in NPDC. The “adsorption/intercalation” mechanism of Na+ in the NPDC is also illustrated by a detailed correlation analysis between electrochemical kinetics analysis and spectral information. Moreover, the corresponding pouch full battery delivers a high energy density of 254.7 Wh kg−1 with excellent rate capability and outstanding cycle stability (89.0% capacity retention) after 500cycles at 1.0C. This work provides a feasible approach to finely modulate the electronic structure of porous HC and facilitate the future design of printable carbon-based SIBs anodes.

A water-based binder with 3D network enabling long-cycle-life silicon/graphite composite anode materials for lithium ion batteries

A binder with strong bonding and 3D network is proven to be beneficial for the electrochemical performance of silicon anode material. Herein, a water-soluble binder with strong adhesion and 3D conductive structure is prepared by a one-pot method. The polymer consists of acrylic acid (AA), acrylamide (AM), and 2-acrylamide-2-methylpropanesulfonic acid (AMPS) forming a terpolymer (PtA), which is grafted to polyvinyl alcohol (PVA) chains to construct a strong hydrogen bonding 3D conductive network structure (PtA/PVA). The polar groups (-COOH and -CONH2) provide strong hydrogen bonding and intermolecular forces for adhesion, while the introduction of lithium salts and sulfonic acid groups provides fast channels for ion transport. In addition, the PVA links with abundant hydroxyl groups, conferring excellent electrochemical performance of silicon/graphite (Si@C 400) composite anodes. As a result, the Si@C 400 anode with the PtA/PVA binder has a reversible capacity of up to 329.8 mAh g−1 at 0.1C, and it shows a prolonged cycle life of 82.0% after 500 cycles at 0.5C. This study provides a promising strategy to design binder for silicon anodes with enhanced electrochemical properties.

Ion-Exchange Route Induced Heterostructured CoS2/FeS Nanoparticles Confined in Hollow N-Doped Carbon Frameworks for Enhanced Sodium Storage Performance

As a result of the high theoretical capacities, transition metal sulfides have attracted increasing attention as potential anodes for sodium-ion batteries (SIBs), but severely suffer from large volumetric variations, sluggish kinetics, and polysulfide shuttling. Herein, utilizing metal–organic frameworks (MOFs) as functional templates, heterostructured CoS2/FeS nanoparticles confined in a hollow N-doped carbon framework are successfully fabricated via a controlled ion-exchange reaction combined with subsequent carbonization and sulfurization processes. The construction of CoS2/FeS heterointerfaces promotes electron transfer and provides more active sites, while the derived N-doped carbon framework with a unique hollow interior effectively improves the electrical conductivity, alleviates the volumetric variations, and facilitates the sodium storage process with shortened Na+ diffusion paths. As anodes for SIBs, the optimal CoS2/FeS hybrid composite exhibits a high initial Coulombic efficiency (ICE) of 89.3%, a prolonged cycle life with a capacity of 494 mAh g–1 over 500 cycles under a current density of 1.0 A g–1, and an excellent rate capability of 428 mAh g–1 at 5.0 A g–1, showing the great promise for SIBs. This research offers an efficient and feasible approach for exploring and fabricating bimetallic sulfide heterostructures with a unique hollow structure for high-performance metal-ion batteries.

Fabrication of cerium nickel oxide (CeNiO3) nanoparticle on vanadium tetra sulphide (VS4) nanosheet composite materials as an enhanced electrode for supercapacitor applications

The CeNiO3 (CNO) is perceived as a promising anode material for supercapacitor applications because of its stable structure and prolonged cycle life. A series of CNO nanospheres anchored on a chain-like structure of VS4 (VS) with high sulphur content are successfully synthesized by in situ hydrothermal reaction. The CNO nanosphere anchoring on the layered VS structure of optimised sample exhibits an enhanced specific capacity by ≈2.76 times over pristine CNO and ≈9.75 times over pristine VS. When the CNO nanosphere is decorated over the layered surface of VS, which reduces the stacking of the nanosheet and diminishes volume expansion and contraction during the long charge-discharge cycles. Importantly, our research study suggests that the sulphur-oxide combination facilitates a diffusion-driven charge storage mechanism via a redox reaction, while higher sulphur content enhances surface-controlled charge storage. Additionally, an asymmetric supercapacitor is fabricated using CNO@VS10 as positive electrode and activated carbon (AC) as negative electrode, which exhibits maximum specific energy of 84.6 W h kg−1 with a specific power of 1094 W kg−1. In addition, DFT studies are utilized to support the experimental observations. Moreover, an array of LEDs displaying NML in printed circuit board (PCB) is lit up by utilizing CR2032 coin-cells connected in series.

Super-three-dimensional lithiophilic Cu-based current collector for anode-free lithium metal battery

The formation of Li dendrites and dead Li, which causes short circuits, continuous side reactions, low Coulombic efficiency (CE) and thermal runaway, severely hinders the development of anode-free lithium metal batteries. Here, Cu-based current collector with super-three-dimensional lithiophilic modification layer is developed by the pyrolysis of resorcinol formaldehyde on 3D engineered copper mesh (a-RF@3D CM). The modification layer, consisting of highly dispersed CuOx sites in the O-containing defective carbon, together with the super-three-dimensional microstructure exhibits excellent lithiophilicity and capability to effectively reduce the nucleation overpotential, accommodate the uniform dendrite-free lithium deposition, promote stable and inorganic-rich solid electrolyte interphase formation, and improve the cycle stability. As a result, the a-RF@3D CM current collector exhibits reduced nucleation overpotential of 14.2 mV and prolonged cycling life over 400 cycles with average CE >98.5%. In the LiFePO4||a-RF@3D CM anode-free cell, average CE of 99.50% and capacity retention of 60.66% are successfully achieved after 100 cycles. Meanwhile, average CE 99.78% and capacity retention of 64.43% are successfully achieved in LiFePO4||Li@a-RF@3D CM cell (N/P = 1.6) after 200 cycles. The work provides feasible way to realize the fabrication of anode-free lithium metal batteries and also enhance the understanding of solid electrolyte interface evolution and regulation strategy of Li plating–stripping in advanced Li metal-based batteries.

MOF–Derived N–Doped C @ CoO/MoC Heterojunction Composite for Efficient Oxygen Reduction Reaction and Long-Life Zn–Air Battery

The high activity and reliability of bifunctional oxygen catalysts are imperative for rechargeable metal–air batteries. However, the preparation of bifunctional non–noble metal electrocatalysts with multiple active sites remains a great challenge. Herein, an MOF–derived N–doped C–loaded uniformly dispersed CoO/MoC heterojunction catalyst for high–performance dual function was prepared by a simple “codeposition–pyrolysis” method. Experimental investigations revealed that the formation of the heterojunction can tailor the valence of Co and Mo sites, which impressively modulates the electronic properties of the active sites and promotes the electrocatalytic processes. The optimal catalyst reveals a high–wave half potential (E1/2 = 0.841 V) for ORR and a low overpotential (E10 = 348 mV) for OER. The NCCM–600–based Zn–air battery displays a high peak power density of 133.36 mW cm−2 and a prolonged cycling life of more than 650 h. This work provides avenues for the development of functional materials with enhanced properties in a variety of practical energy applications.

In situ construction of zinc-rich polymeric solid–electrolyte interface for high-performance zinc anode

With their excellent reliability and environmental friendliness, zinc-ion batteries (ZIBs) are regarded as potential energy storage technologies. Unfortunately, their poor cycling durability and low Coulombic effectiveness (CE), driven by dendritic growth and surface passivation on the Zn anode, severely restrict their commercialization. Herein, we describe the in situ construction of a Zn-rich polymeric solid–electrolyte interface (SEI) using polyacrylic acid (PAA) as an electrolyte additive. On the one hand, the PAA SEI layer offers evenly distributed nucleation sites and promotes ion transport, hence suppressing dendrite growth. On the other hand, the SEI layer prevents direct contact between the Zn foil and the electrolyte, thus inhibiting side reactions. Additionally, the robust coordination of PAA with Zn2+ and the SEI layer's good adherence to the Zn foil provide long-term protection to the Zn anode. As a result, symmetric cells and Zn/V2O5 cells all deliver prolonged cycle life and superior electrochemical efficiency.

Reviving Inactive Lithium and Stabilizing Lithium Deposition for Improving the Performance of Anode-Free Lithium–Sulfur Batteries

Anode-free lithium–sulfur batteries (AFLSBs) show a surprisingly prolonged cycle life 2-fold higher than anode-free lithium metal batteries. The principal difference is the presence of an intrinsic polysulfide (PS) shuttle between electrodes in AFLSBs. However, the underlying mechanism for the impact of PS redox species on the electrochemical performance of AFLSBs is not clearly understood. Herein, we investigate the role of PS redox species in retrieving inactive lithium for compensating lithium inventory loss using titration gas chromatography, thereby quantifying inactive lithium accumulated after several cycles. Moreover, XPS analysis reveals reduced lithium sulfide (Li2S/Li2S2) species formed through PS redox shuttle refresh inactive solid electrolyte interface (SEI) composition and stabilize the consecutive cycle lithium deposition. Interestingly, synchrotron-based operando transmission X-ray microscopy (TXM) reveals dense and granular electrodeposited lithium morphologies in AFLSBs. Therefore, the interplay between reviving inactive lithium for compensating lithium inventory loss and stabilizing lithium electrodeposition endows high electrochemical performance in AFLSBs.

Improvement on cyclic stability of AB4-type La–Mg–Ni-based hydrogen storage alloys via merging Y element for nickel-metal hydride batteries

The newly discovered AB4-type superlattice structure of rare earth–Mg–Ni-based (RE–Mg–Ni) alloys have extended cycle life and power performance, which are a promising anode material for nickel-metal hydride (Ni/MH) battery. However, the cycling stability still needs to be enhanced to meet the requirement of utilization. Herein, we design low cost single-phase AB4-type alloys and clarify the effect of merging Y on Mg on the electrochemical performance. Studies show that the cycling stability of the alloy is significantly enhanced after partial replacement of Y on Mg, where the discharge capacity of the La0.65Sm0.12Y0.10Mg0.13Ni3.60Al0.15 alloy maintains 234.5 mAh g−1 after cycling 500 times with a capacity retention of 61.8%, in contrast to 191.6 mAh g−1 with 50.6% of the La0.65Sm0.12Mg0.23Ni3.60Al0.15 alloy. The prolonged cycling life relates to the reduction of pulverization due to the increased matching degree of the sublattice structure, and the prevention of oxidation in terms of the oxide film of Y. Whereas, the discharge ability at high rates and low temperatures of the alloy are deteriorated after Y replacement. The results pave the way to the component design of the RE–Mg–Ni-based alloys for long-life Ni/MH batteries.

Glyoxylic-Acetal-Based Electrolytes for Sodium-Ion Batteries and Sodium-Ion Capacitors.

A comprehensive study on the properties and implementation of glyoxylic-acetals in sodium-ion energy storage systems is presented. Electrolytes containing 1,1,2,2-tetramethoxyethane (tetramethoxyglyoxal, TMG), 1,1,2,2-tetraethoxyethane (tetraethoxyglyoxal, TEG) and a mixture of the latter with propylene carbonate (PC) exhibit increased thermal stabilities and higher flash points compared to classical electrolytes based on carbonates as solvents. Due to its favorable properties, 1 m NaTFSI in TEG/PC (3 : 7), has been selected and used for sodium-ion energy storage systems based on a Prussian Blue (PB) positive electrode and a hard carbon (HC) negative electrode. Compared to conventional electrolyte (based on a 1 : 1 mixture of ethylene carbonate, EC, and dimethyl carbonate, DMC), this glyoxylic-acetal electrolyte provides competitive capacity and prolonged cycle life. Postmortem XPS analysis indicates that the electrode-electrolyte interphases formed in presence of TEG are thicker and presumably more protective, inhibiting typical degradation processes of the electrodes. Furthermore, it is demonstrated that the suitable properties of TEG on the cycling stability can also be exploited for the construction of highly stable sodium-ion capacitors.

Porous Organic Cage as a Sulfur Host for Upgrading Capacity and Longevity of Li–S Batteries

Suffering from the severe shuttle effect, constructing high-performance lithium–sulfur (Li–S) batteries with high capacity and prolonged cycling life remains a great challenge. Developing porous host materials for sulfur loading remains a tendency. Porous organic cages (POCs), as a kind of porous material, exhibit potential in energy storage and conversion because of their inherent cavities and plentiful active sites. Herein, two POC materials of CPOC-301 and HPOC-401 with large octahedral cavities and abundant N and O heteroatoms were explored as host materials for loading a high sulfur content of 84 wt % in Li–S batteries. The resulting CPOC-301-S and HPOC-401-S cathodes exhibit improved electrochemical performances with high specific capacity (1302 and 1109 mA h g–1 at 0.05 C, respectively) and excellent cycling reversibility and stability (a low average capacity fading rate of 0.015% for 2500 cycles at 5 C for CPOC-301-S). Moreover, the interconversion of keto-enamine in CPOC-301 could accelerate the redox kinetics. This work provides the blueprint for POC families applied as promising host materials for advanced Li–S batteries.

Flexible Hierarchical Co‐Doped NiS2@CNF‐CNT Electron Deficient Interlayer with Grass‐Roots Structure for Li–S Batteries

AbstractThe key means to improve the performance of lithium–sulfur batteries (LSBs) is to reduce the internal resistance by building an electronic/ionic pathway and to accelerate the conversion kinetics of lithium polysulfides (LiPSs) through modulation of interface functions. Herein, inspired by a grass root system, a flexible hierarchical CNF‐CNT (carbon nanofiber‐carbon nanotube) membrane decorated with Co‐doped NiS2nanoparticles (Co‐NiS2@CNF‐CNT) is designed as an interlayer for LSBs, in which the in situ grown CNTs (root hairs) are wound on CNF (roots). Density functional theory (DFT) calculations show that Co doping introduces electron‐deficient regions at the doping sites in NiS2, thus improving chemical adsorption and catalytic activities toward LiPSs. The cell pairs with the Co‐NiS2@CNF‐CNT interlayer exhibit a high rate performance of 951.4 mAh g−1at 3 C, a reversible capacity of 944.1 mAh g−1after 500 cycles at 0.2 C, and a prolonged cycle life of 3000 cycles at 5 C. More importantly, an areal capacity of 7.96 mAh cm−2is achieved with a sulfur loading of 9.6 mg cm−2. This work provides a strategy for enhancing the electrochemical performance of LSBs by combining 3D hierarchical conductive skeletons and electron‐deficient functional adsorption and catalysis materials.

An integrated architecture of mutually infiltrated nanoarray cathode and polymer electrolyte improves the performances of solid-state lithium−oxygen batteries

In solid-state lithium−oxygen (Li−O2) batteries, solid polymer electrolytes (SPEs) usually cannot efficiently infiltrate into porous cathodes to form sufficient cathode/electrolyte/oxygen triple-phase interfaces for oxygen reduction reactions. The confined cathode/SPE interfaces in cathode/SPE/lithium anode sandwich-type cells only provide limited reaction sites accessible to lithium ion, electron, and oxygen gas. The resulted high interface resistances challenge the practical application of solid-state Li−O2 batteries. This work proposes an integrated architecture of mutually infiltrated nanoarray cathode and polymer electrolyte to produce more active sites and therefore lower the interface resistance. In detail, the integrated assemblies of cathode and SPE (Co3O4@CC-SPE) are prepared via partially infiltrating polymer and salt solution into Co3O4 nanosheets array (Co3O4@CC). The abundant cathode/SPE/oxygen triple-phase interfaces and the three-dimensional ion and electron-conducting networks in the Co3O4@CC-SPE assemblies achieve lower polarization, higher reversible capacity, and prolonged cycle life of solid-state Li−O2 batteries. The Co3O4@CC-SPE/Li cell shows a higher discharge capacity of 3.3 mA h cm−2 (6600 mA h g−1) and a higher 101 stable cycles than the 1.2 mA h cm−2 (2400 mA h g−1) and only 15 cycles of the sandwich-type counterparts. The present work provides new opportunities for developing practical solid-state Li−O2 batteries via the mutually infiltrated nanoarray cathode and polymer electrolyte.

Nonepitaxial Electrodeposition of (002)-Textured Zn Anode on Textureless Substrates for Dendrite-Free and Hydrogen Evolution-Suppressed Zn Batteries.

Nontoxic and safe aqueous Zn batteries are largely restricted by the detrimental dendrite growth and hydrogen evolution of Zn metal anode. The (002)-textured Zn electrodeposition, demonstrated as an effective approach for solving these issues, is nevertheless achieved mainly by epitaxial or hetero-epitaxial deposition of Zn on pre-textured substrates. Herein, the electrodeposition of (002)-textured and compact Zn on textureless substrates (commercial Zn, Cu, and Ti foils) at a medium-high galvanostatic current density is reported. According to the systematic investigations on Zn nucleation and growth behaviors, this is ascribed to two reasons: i) the promoted nonepitaxial nucleation of fine horizontal (002) nuclei at increased overpotential and ii) the competitive growth advantages of (002)-orientated nuclei. The resulting freestanding (002)-textured Zn film exhibits significantly suppressed hydrogen evolution and prolonged Zn plating-stripping cycling life, achieving over 2100 mAh cm-2 cumulative capacity under a current density of 10 mA cm-2 and a high depth of discharge (DOD) of 45.5%. Therefore, this study provides both fundamental and practical insights into long-life Zn metal batteries.

Confronting Sulfur Electrode Passivation and Li Metal Electrode Degradation in Lithium-Sulfur Batteries Using Thiocyanate Anion.

Salt anions with a high donor number (DN) enable high sulfur utilization in lithium-sulfur (Li-S) batteries by inducing three-dimensional (3D) Li2 S growth. However, their insufficient compatibility with Li metal electrodes limits their cycling stability. Herein, a new class of salt anion, thiocyanate (SCN- ), is presented, which features a Janus character of electron donor and acceptor. Due to a strong Li+ coordination by SCN- and the direct interaction of SCN- with polysulfide anions, the LiSCN electrolyte has a remarkably high lithium polysulfide solubility. This electrolyte induces 3D Li2 S formation and ameliorates cathode passivation, even more than Br- , a typical high DN anion. Moreover, SCN- forms a Li3 N-enriched stable SEI layer at the surface of the Li metal electrode, enhancing cycling stability. A Li-S battery with the LiSCN electrolyte shows high current density operation (2.54mA cm⁻2 ) with high discharge capacity (1133 mAh g⁻1 ) and prolonged cycle life (100 cycles). This work demonstrates that the cathode and anode performance in a Li-S battery can be simply and concurrently enhanced by the single salt anion.

Yolk-shell porous Fe3O4@C anchored on graphene as anode for Li-ion half/full batteries with high rate capability and long cycle life

Iron oxides have been widely studied as anode materials for lithium-ion batteries (LIBs) due to their high conductivity (5 × 104 S m−1) and high capacity (ca. 926 mAh g−1). However, having a large volume change and being highly prone to dissolution/aggregation during charge/discharge cycles hinder their practical application. Herein, we report a design strategy for constructing yolk-shell porous Fe3O4@C anchored on graphene nanosheets (Y-S-P-Fe3O4/GNs@C). This particular structure can not only introduce sufficient internal void space to accommodate the volume change of Fe3O4 but also afford a carbon shell to restrict Fe3O4 overexpansion, thus greatly improving capacity retention. In addition, the pores in Fe3O4 can effectively promote ion transport, and the carbon shell anchored on graphene nanosheets is capable of enhancing overall conductivity. Consequently, Y-S-P-Fe3O4/GNs@C features a high reversible capacity of 1143 mAh g−1, an excellent rate capacity (358 mAh g−1 at 10.0 A g−1), and a prolonged cycle life with robust cycling stability (579 mAh g−1 remaining after 1800 cycles at 2.0 A g−1) when assembled into LIBs. The assembled Y-S-P-Fe3O4/GNs@C//LiFePO4 full-cell delivers a high energy density of 341.0 Wh kg−1 at 37.9 W kg−1. The Y-S-P-Fe3O4/GNs@C is proved to be an efficient Fe3O4-based anode material for LIBs.

Material, configuration, and fabrication designs for lean-electrolyte lithium–sulfur cell with a high-loading sulfur cathode

The lithium–sulfur battery is considered a promising candidate for third-generation commercial rechargeable batteries because of the high theoretical capacity of sulfur (1675 mA h g−1). However, the insulating solid-state active material causes low sulfur loading and content, challenging the increase of the energy density. The complex conversion reaction between solid-state and liquid-state active materials during charging/discharging process leads to high electrolyte usage and short cycle life. These issues affecting the evaluation of the electrochemical characteristics and performance of lithium–sulfur batteries are important for the commercialization of this technology. Herein, we propose a design of cathode material, configuration, and fabrication. This design realizes a porous carbon electrospun substrate built up with nonwoven carbon nanofibers having low nanoporosity. The carbon electrospun substrate is used as a porous electrode substrate to encapsulate insulating sulfur using a hot-pressing method, forming a hot-pressed electrospun cathode. The carbon electrospun substrate has a conductive, low-weight network to accommodate and exploit a high amount of sulfur (8 mg cm−2 and 73 wt%) at low electrolyte-to-sulfur ratios (7–4 μL mg−1), which achieves high charge-storage capacity (740 mA h g−1), large energy density (11.8 mW h cm−2), excellent rate performance (C/20–C/2 rates), and a prolonged cycle life (200 cycles).