Porosity‐Controlled TiNb2O7 Microspheres with Partial Nitridation as A Practical Negative Electrode for High‐Power Lithium‐Ion Batteries

Titanium niobium oxide (TiNb₂O₇) has been recognized as a promising anode material for lithium‐ion batteries (LIBs) in view of its potential to operate at high rates with improved safety and high theoretical capacity of 387 mAh g^?1. However, it suffers from poor Li⁺ ion diffusivity and low electronic conductivity originated from its wide band gap energy (E_g > 2 eV). Here, porous TiNb₂O₇ microspheres (PTNO MSs) are prepared via a facile solvothermal reaction. PTNO MSs have a particle size of ≈1.2 μm and controllable pore sizes in the range of 5–35 nm. Ammonia gas nitridation treatment is conducted on PTNO MSs to introduce conducting Ti_1?xNb_xN layer on the surface and form nitridated PTNO (NPTNO) MSs. The porous structure and conducting Ti_1?xNb_xN layer enhance the transport kinetics associated with Li⁺ ions and electrons, which leads to significant improvement in electrochemical performance. As a result, the NPTNO electrode shows a high discharge capacity of ≈265 mAh g^?1, remarkable rate capability (≈143 mAh g^?1 at 100 C) and durable long‐term cyclability (≈91% capacity retention over 1000 cycles at 5 C). These results demonstrate the great potential of TiNb₂O₇ as a practical high‐rate anode material for LIBs.     

“Water‐in‐Salt” Electrolyte Makes Aqueous Sodium‐Ion Battery Safe,Green, and Long‐Lasting

Narrow electrochemical stability window (1.23 V) of aqueous electrolytes is always considered the key obstacle preventing aqueous sodium‐ion chemistry of practical energy density and cycle life. The sodium‐ion water‐in‐salt electrolyte (NaWiSE) eliminates this barrier by offering a 2.5 V window through suppressing hydrogen evolution on anode with the formation of a Na⁺‐conducting solid‐electrolyte interphase (SEI) and reducing the overall electrochemical activity of water on cathode. A full aqueous Na‐ion battery constructed on Na_0.66[Mn_0.66Ti_0.34]O₂ as cathode and NaTi₂(PO₄)₃ as anode exhibits superior performance at both low and high rates, as exemplified by extraordinarily high Coulombic efficiency (>99.2%) at a low rate (0.2 C) for >350 cycles, and excellent cycling stability with negligible capacity losses (0.006% per cycle) at a high rate (1 C) for >1200 cycles. Molecular modeling reveals some key differences between Li‐ion and Na‐ion WiSE, and identifies a more pronounced ion aggregation with frequent contacts between the sodium cation and fluorine of anion in the latter as one main factor responsible for the formation of a dense SEI at lower salt concentration than its Li cousin.     

Thick Binder‐Free Electrodes for Li–Ion Battery Fabricated Using Templating Approach and Spark Plasma Sintering Reveals High Areal Capacity

The templating approach is a powerful method for preparing porous electrodes with interconnected well‐controlled pore sizes and morphologies. The optimization of the pore architecture design facilitates electrolyte penetration and provides a rapid diffusion path for lithium ions, which becomes even more crucial for thick porous electrodes. Here, NaCl microsize particles are used as a templating agent for the fabrication of 1 mm thick porous LiFePO₄ and Li₄Ti₅O₁₂ composite electrodes using spark plasma sintering technique. These sintered binder‐free electrodes are self‐supported and present a large porosity (40%) with relatively uniform pores. The electrochemical performances of half and full batteries reveal a remarkable specific areal capacity (20 mA h cm^?2), which is 4 times higher than those of 100 µm thick electrodes present in conventional tape‐casted Li–ion batteries (5 mA h cm^?2). The 3D morphological study is carried out using full field transmission X‐ray microscopy in microcomputed tomography mode to obtain tortuosity values and pore size distributions leading to a strong correlation with their electrochemical properties. These results also demonstrate that the coupling between the salt templating method and the spark plasma sintering technique turns out to be a promising way to fabricate thick electrodes with high energy density.     

Mn‐Rich P′2‐Na0.67[Ni0.1Fe0.1Mn0.8]O2 as High‐Energy‐Density and Long‐Life Cathode Material for Sodium‐Ion Batteries

Herein, P′2‐type Na_0.67[Ni_0.1Fe_0.1Mn_0.8]O₂ is introduced as a promising new cathode material for sodium‐ion batteries (SIBs) that exhibits remarkable structural stability during repetitive Na⁺ de/intercalation. The O? Ni? O? Mn? O? Fe? O bond in the octahedra of transition‐metal layers is used to suppress the elongation of the Mn? O bond and to improve the electrochemical activity, leading to the highly reversible Na storage mechanism. A high discharge capacity of ≈220 mAh g^?1 (≈605 Wh kg^?1) is delivered at 0.05 C (13 mAg^?1) with a high reversible capacity of ≈140 mAh g^?1 at 3 C and excellent capacity retention of 80% over 200 cycles. This performance is associated with the reversible P′2–OP4 phase transition and small volume change upon charge and discharge (≈3%). The nature of the sodium storage mechanism in a full cell paired with a hard carbon anode reveals an unexpectedly high energy density of ≈542 Wh kg^?1 at 0.2 C and good capacity retention of ≈81% for 500 cycles at 1 C (260 mAg^?1).     

Boosting Sodium Storage in TiF3/Carbon Core/Sheath Nanofibers through an Efficient Mixed‐Conducting Network

Sodium‐ion batteries (SIBs) are considered to be promising energy storage devices for large‐scale grid storage application due to the vast earth‐abundance and low cost of sodium‐containing precursors. Designing and fabricating a highly efficient anode is one of the keys to improve the electrochemical performance of SIBs. Recently, fluoride‐based materials are found to show an exceptional anode function with high theoretical specific capacity, based on open‐framework structure enabling Na insertion and also exhibiting improved safety. However, fluoride‐based materials suffer from sluggish kinetics and poor capacity retention essentially due to low electric conductivity. Here, an efficient mixed‐conducting network offering fast pathways is proposed to address these issues. This network relies on titanium fluoride?carbon (TiF₃?C) core/sheath nanofibers that are prepared via electrospinning. Such highly interconnected electrodes exhibit an enhanced and faster sodium storage performance. Carbon sheath nanofibers are key to an efficient ion‐ and electron‐conducting network that enable Na⁺/e^? transfer to reach the nanosized TiF₃. In addition, in‐situ‐converted Ti and NaF particles embedded in the carbon matrix allow high reversible interfacial storage. As a result, the TiF₃?C core/sheath electrode exhibits a high capacity of 161 mAh g^?1 at a high current density of 1000 mA g^?1 over 2000 cycles.     

An Ion‐Exchange Promoted Phase Transition in a Li‐Excess Layered Cathode Material for High‐Performance Lithium Ion Batteries

A new approach to intentionally induce phase transition of Li‐excess layered cathode materials for high‐performance lithium ion batteries is reported. In high contrast to the limited layered‐to‐spinel phase transformation that occurred during in situ electrochemical cycles, a Li‐excess layered Li[Li_0.2Mn_0.54Ni_0.13Co_0.13]O₂ is completely converted to a Li₄Mn₅O₁₂‐type spinel product via ex situ ion‐exchanges and a post‐annealing process. Such a layered‐to‐spinel phase conversion is examined using in situ X‐ray diffraction and in situ high‐resolution transmission electron microscopy. It is found that generation of sufficient lithium ion vacancies within the Li‐excess layered oxide plays a critical role for realizing a complete phase transition. The newly formed spinel material exhibits initial discharge capacities of 313.6, 267.2, 204.0, and 126.3 mAh g^?1 when cycled at 0.1, 0.5, 1, and 5 C (1 C = 250 mA g^?1), respectively, and can retain a specific capacity of 197.5 mAh g^?1 at 1 C after 100 electrochemical cycles, demonstrating remarkably improved rate capability and cycling stability in comparison with the original Li‐excess layered cathode materials. This work sheds light on fundamental understanding of phase transitions within Li‐excess layered oxides. It also provides a novel route for tailoring electrochemical performance of Li‐excess layered cathode materials for high‐capacity lithium ion batteries.     

Sodium Storage and Transport Properties in Layered Na2Ti3O7 for Room‐Temperature Sodium‐Ion Batteries

Layered sodium titanium oxide, Na₂Ti₃O₇, is synthesized by a solid‐state reaction method as a potential anode for sodium‐ion batteries. Through optimization of the electrolyte and binder, the microsized Na₂Ti₃O₇ electrode delivers a reversible capacity of 188 mA h g^?1 in 1 M NaFSI/PC electrolyte at a current rate of 0.1C in a voltage range of 0.0–3.0 V, with sodium alginate as binder. The average Na storage voltage plateau is found at ca. 0.3 V vs. Na⁺/Na, in good agreement with a first‐principles prediction of 0.35 V. The Na storage properties in Na₂Ti₃O₇ are investigated from thermodynamic and kinetic aspects. By reducing particle size, the nanosized Na₂Ti₃O₇ exhibits much higher capacity, but still with unsatisfied cyclic properties. The solid‐state interphase layer on Na₂Ti₃O₇ electrode is analyzed. A zero‐current overpotential related to thermodynamic factors is observed for both nano‐ and microsized Na₂Ti₃O₇. The electronic structure, Na⁺ ion transport and conductivity are investigated by the combination of first‐principles calculation and electrochemical characterizations. On the basis of the vacancy‐hopping mechanism, a quasi‐3D energy favorable trajectory is proposed for Na₂Ti₃O₇. The Na⁺ ions diffuse between the TiO₆ octahedron layers with pretty low activation energy of 0.186 eV.     

Flexible Ion‐Conducting Composite Membranes for Lithium Batteries

The use of metallic lithium anodes enables higher energy density and higher specific capacity Li‐based batteries. However, it is essential to suppress lithium dendrite growth during electrodeposition. Li‐ion‐conducting ceramics (LICC) can mechanically suppress dendritic growth but are too fragile and also have low Li‐ion conductivity. Here, a simple, versatile, and scalable procedure for fabricating flexible Li‐ion‐conducting composite membranes composed of a single layer of LICC particles firmly embedded in a polymer matrix with their top and bottom surfaces exposed to allow for ionic transport is described. The membranes are thin (<100 μm) and possess high Li‐ion conductance at thicknesses where LICC disks are mechanically unstable. It is demonstrated that these membranes suppress Li dendrite growth even when the shear modulus of the matrix is lower than that of lithium. It is anticipated that these membranes enable the use of metallic lithium anodes in conventional and solid‐state Li‐ion batteries as well as in future Li? S and Li? O₂ batteries.     

Slurry‐Fabricable Li+‐Conductive Polymeric Binders for Practical All‐Solid‐State Lithium‐Ion Batteries Enabled by Solvate Ionic Liquids

For mass production of all‐solid‐state lithium‐ion batteries (ASLBs) employing highly Li⁺ conductive and mechanically sinterable sulfide solid electrolytes (SEs), the wet‐slurry process is imperative. Unfortunately, the poor chemical stability of sulfide SEs severely restrict available candidates for solvents and in turn polymeric binders. Moreover, the binders interrupt Li⁺‐ionic contacts at interfaces, resulting in the below par electrochemical performance. In this work, a new scalable slurry fabrication protocol for sheet‐type ASLB electrodes made of Li⁺‐conductive polymeric binders is reported. The use of intermediate‐polarity solvent (e.g., dibromomethane) for the slurry allows for accommodating Li₆PS₅Cl and solvate‐ionic‐liquid‐based polymeric binders (NBR‐Li(G3)TFSI, NBR: nitrile?butadiene rubber, G3: triethylene glycol dimethyl ether, LiTFSI: lithium bis(trifluoromethanesulfonyl)imide) together without suffering from undesirable side reactions or phase separation. The LiNi_0.6Co_0.2Mn_0.2O₂ and Li₄Ti₅O₁₂ electrodes employing NBR‐Li(G3)TFSI show high capacities of 174 and 160 mA h g^?1 at 30 °C, respectively, which are far superior to those using conventional NBR (144 and 76 mA h g^?1). Moreover, high areal capacity of 7.4 mA h cm^?2 is highlighted for the LiNi_0.7Co_0.15Mn_0.15O₂ electrodes with ultrahigh mass loading of 45 mg cm^?2. The facilitated Li⁺‐ionic contacts at interfaces paved by NBR‐Li(G3)TFSI are evidenced by the complementary analysis from electrochemical and ⁷Li nuclear magnetic resonance measurements.     

Site‐Selective In Situ Electrochemical Doping for Mn‐Rich Layered Oxide Cathode Materials in Lithium‐Ion Batteries

Various doped materials have been investigated to improve the structural stability of layered transition metal oxides for lithium‐ion batteries. Most doped materials are obtained through solid state methods, in which the doping of cations is not strictly site selective. This paper demonstrates, for the first time, an in situ electrochemical site‐selective doping process that selectively substitutes Li⁺ at Li sites in Mn‐rich layered oxides with Mg²⁺. Mg²⁺ cations are electrochemically intercalated into Li sites in delithiated Mn‐rich layered oxides, resulting in the formation of [Li_1?xMg_y][Mn_1?zM_z]O₂ (M = Co and Ni). This Mg²⁺ intercalation is irreversible, leading to the favorable doping of Mg²⁺ at the Li sites. More interestingly, the amount of intercalated Mg²⁺ dopants increases with the increasing amount of Mn in Li_1?x[Mn_1?zM_z]O₂, which is attributed to the fact that the Mn‐to‐O electron transfer enhances the attractive interaction between Mg²⁺ dopants and electronegative O^δ? atoms. Moreover, Mg²⁺ at the Li sites in layered oxides suppresses cation mixing during cycling, resulting in markedly improved capacity retention over 200 cycles. The first‐principle calculations further clarify the role of Mg²⁺ in reduced cation mixing during cycling. The new concept of in situ electrochemical doping provides a new avenue for the development of various selectively doped materials.     

Exceptionally Enhanced Electrode Activity of (Pr,Ce)O2−δ‐Based Cathodes for Thin‐Film Solid Oxide Fuel Cells

It is shown that an electrochemically‐driven oxide overcoating substantially improves the performance of metal electrodes in high‐temperature electrochemical applications. As a case study, Pt thin films are overcoated with (Pr,Ce)O_2?δ (PCO) by means of a cathodic electrochemical deposition process that produces nanostructured oxide layers with a high specific surface area and uniform metal coverage and then the coated films are examined as an O₂‐electrode for thin‐film‐based solid oxide fuel cells. The combination of excellent conductivity, reactivity, and durability of PCO dramatically improves the oxygen reduction reaction rate while maintaining the nanoscale architecture of PCO layers and thus the performance of the PCO‐coated Pt thin‐film electrodes at high temperatures. As a result, with an oxide coating step lasting only 5 min, the electrode resistance is successfully reduced by more than 1000 times at 500 °C in air. These observations provide a new direction for the design of high‐performance electrodes for high‐temperature electrochemical cells.     

Exploiting the Condensation Reactions of Acetophenone to Engineer Carbon‐Encapsulated Nb2O5 Nanocrystals for High‐Performance Li and Na Energy Storage Systems

Efficient synthetic methods to produce high‐performance electrode‐active materials are crucial for developing energy storage devices for large‐scale applications, such as hybrid supercapacitors (HSCs). Here, an effective approach to obtain controllable carbon‐encapsulated T‐Nb₂O₅ nanocrystals (NCs) is presented, based on the solvothermal treatment of NbCl₅ in acetophenone. Two separate condensation reactions of acetophenone generate an intimate and homogeneous mixture of Nb₂O₅ particles and 1,3,5‐triphenylbenzene (TPB), which acts as a unique carbon precursor. The electrochemical performance of the resulting composites as anode electrode materials can be tuned by varying the Nb₂O₅/TPB ratio. Remarkable performances are achieved for Li‐ion and Na‐ion energy storage systems at high charge–discharge rates (specific capacities of ≈90 mAh g^?1 at 100 C rate for lithium and ≈125 mAh g^?1 at 20 C for sodium). High energy and power densities are also achieved with Li‐ and Na‐ion HSC devices constructed by using the Nb₂O₅/C composites as anode and activated carbon (YPF‐50) as cathode, demonstrating the excellent electrochemical properties of the materials synthesized with this approach.     

Design and Performance of Rechargeable Sodium Ion Batteries,and Symmetrical Li‐Ion Batteries with Supercapacitor‐Like Power Density Based upon Polyoxovanadates

The polyanion Li₇V₁₅O₃₆(CO₃) is a nanosized molecular cluster (≈1 nm in size), that has the potential to form an open host framework with a higher surface‐to‐bulk ratio than conventional transition metal oxide electrode materials. Herein, practical rechargeable Na‐ion batteries and symmetric Li‐ion batteries are demonstrated based on the polyoxovanadate Li₇V₁₅O₃₆(CO₃). The vanadium centers in {V₁₅O₃₆(CO₃)} do not all have the same V^IV/V redox potentials, which permits symmetric devices to be created from this material that exhibit battery‐like energy density and supercapacitor‐like power density. An ultrahigh specific power of 51.5 kW kg^?1 at 100 A g^?1 and a specific energy of 125 W h kg^?1 can be achieved, along with a long cycling life (>500 cycles). Moreover, electrochemical and theoretical studies reveal that {V₁₅O₃₆(CO₃)} also allows the transport of large cations, like Na⁺, and that it can serve as the cathode material for rechargeable Na‐ion batteries with a high specific capacity of 240 mA h g^?1 and a specific energy of 390 W h kg^?1 for the full Na‐ion battery. Finally, the polyoxometalate material from these electrochemical energy storage devices can be easily extracted from spent electrodes by simple treatment with water, providing a potential route to recycling of the redox active material.     

K‐Ion Storage Enhancement in Sb2O3/Reduced Graphene Oxide Using Ether‐Based Electrolyte

In this work, an ether‐based electrolyte is adopted instead of conventional ester‐based electrolyte for an Sb₂O₃‐based anode and its enhancement mechanism is unveiled for K‐ion storage. The anode is fabricated by anchoring Sb₂O₃ onto reduced graphene oxide (Sb₂O₃‐RGO) and it exhibits better electrochemical performance using an ether‐based electrolyte than that using a conventional ester‐based electrolyte. By optimizing the concentration of the electrolyte, the Sb₂O₃‐RGO composite delivers a reversible specific capacity of 309 mAh g^?1 after 100 cycles at 100 mA g^?1. A high specific capacity of 201 mAh g^?1 still remains after 3300 cycles (111 days) at 500 mA g^?1 with almost no decay, exhibiting a longer cycle life compared with other metallic oxides. In order to further reveal the intrinsic mechanism, the energy changes for K atom migrating from surface into the sublayer of Sb₂O₃ are explored by density functional theory calculations. According to the result, the battery using the ether‐based electrolyte exhibits a lower energy change and migration barrier than those using other electrolytes for K‐ion, which is helpful to improve the K‐ion storage performance. It is believed that the work can provide deep understanding and new insight to enhance electrochemical performance using ether‐based electrolytes for KIBs.     

Open‐Structured V2O5·nH2O Nanoflakes as Highly Reversible Cathode Material for Monovalent and Multivalent Intercalation Batteries

The high‐capacity cathode material V₂O₅·n H₂O has attracted considerable attention for metal ion batteries due to the multielectron redox reaction during electrochemical processes. It has an expanded layer structure, which can host large ions or multivalent ions. However, structural instability and poor electronic and ionic conductivities greatly handicap its application. Here, in cell tests, self‐assembly V₂O₅·n H₂O nanoflakes shows excellent electrochemical performance with either monovalent or multivalent cation intercalation. They are directly grown on a 3D conductive stainless steel mesh substrate via a simple and green hydrothermal method. Well‐layered nanoflakes are obtained after heat treatment at 300 °C (V₂O₅·0.3H₂O). Nanoflakes with ultrathin flower petals deliver a stable capacity of 250 mA h g^?1 in a Li‐ion cell, 110 mA h g^?1 in a Na‐ion cell, and 80 mA h g^?1 in an Al‐ion cell in their respective potential ranges (2.0–4.0 V for Li and Na‐ion batteries and 0.1–2.5 V for Al‐ion battery) after 100 cycles.     

Interface‐Engineered All‐Solid‐State Li‐Ion Batteries Based on Garnet‐Type Fast Li+ Conductors

All‐solid‐state Li‐ion batteries based on Li₇La₃Zr₂O₁₂ (LLZO) garnet structures require novel electrode assembly strategies to guarantee a proper Li⁺ transfer at the electrode–electrolyte interfaces. Here, first stable cell performances are reported for Li‐garnet, c‐Li_6.25Al_0.25La₃Zr₂O₁₂, all‐solid‐state batteries running safely with a full ceramics setup, exemplified with the anode material Li₄Ti₅O₁₂. Novel strategies to design an enhanced Li⁺ transfer at the electrode–electrolyte interface using an interface‐engineered all‐solid‐state battery cell based on a porous garnet electrolyte interface structure, in which the electrode material is intimately embedded, are presented. The results presented here show for the first time that all‐solid‐state Li‐ion batteries with LLZO electrolytes can be reversibly charge–discharge cycled also in the low potential ranges (≈1.5 V) for combinations with a ceramic anode material. Through a model experiment, the interface between the electrode and electrolyte constituents is systematically modified revealing that the interface engineering helps to improve delivered capacities and cycling properties of the all‐solid‐state Li‐ion batteries based on garnet‐type cubic LLZO structures.     

High‐Voltage Oxygen‐Redox‐Based Cathode for Rechargeable Sodium‐Ion Batteries

Recently, anionic‐redox‐based materials have shown promising electrochemical performance as cathode materials for sodium‐ion batteries. However, one of the limiting factors in the development of oxygen‐redox‐based electrodes is their low operating voltage. In this study, the operating voltage of oxygen‐redox‐based electrodes is raised by incorporating nickel into P2‐type Na_2/3[Zn_0.3Mn_0.7]O₂ in such a way that the zinc is partially substituted by nickel. As designed, the resulting P2‐type Na_2/3[(Ni_0.5Zn_0.5)_0.3Mn_0.7]O₂ electrode exhibits an average operating voltage of 3.5 V and retains 95% of its initial capacity after 200 cycles in the voltage range of 2.3–4.6 V at 0.1C (26 mA g^?1). Operando X‐ray diffraction analysis reveals the reversible phase transition: P2 to OP4 phase on charge and recovery to the P2 phase on discharge. Moreover, ex situ X‐ray absorption near edge structure and X‐ray photoelectron spectroscopy studies reveal that the capacity is generated by the combination of Ni²⁺/Ni⁴⁺ and O^2?/O^1? redox pairs, which is supported by first‐principles calculations. It is thought that this kind of high voltage redox species combined with oxygen redox could be an interesting approach to further increase energy density of cathode materials for not only sodium‐based rechargeable batteries, but other alkali‐ion battery systems.     

Fast and Stable Proton Conduction in Heavily Scandium‐Doped Polycrystalline Barium Zirconate at Intermediate Temperatures

The environmental benefits of fuel cells and electrolyzers have become increasingly recognized in recent years. Fuel cells and electrolyzers that can operate at intermediate temperatures (300–450 °C) require, in principle, neither the precious metal catalysts that are typically used in polymer‐electrolyte‐membrane systems nor the costly heat‐resistant alloys used in balance‐of‐plant components of high‐temperature solid oxide electrochemical cells. These devices require an electrolyte with high ionic conductivity, typically more than 0.01 S cm^?1, and high chemical stability. To date, however, high ionic conductivities have been found in chemically unstable materials such as CsH₂PO₄, In‐doped SnP₂O₇, BaH₂, and LaH_3?2xO_x. Here, fast and stable proton conduction in 60‐at% Sc‐doped barium zirconate polycrystal, with a total conductivity of 0.01 S cm^?1 at 396 °C for 200 h is demonstrated. Heavy doping of Sc in barium zirconate simultaneously enhances the proton concentration, bulk proton diffusivity, specific grain boundary conductivity, and grain growth. An accelerated stability test under a highly concentrated and humidified CO₂ stream using in situ X‐ray diffraction shows that the perovskite phase is stable over 240 h at 400 °C under 0.98 atm of CO₂. These results show great promises as an electrolyte in solid‐state electrochemical devices operated at intermediate temperatures.     

A Self‐Forming Composite Electrolyte for Solid‐State Sodium Battery with Ultralong Cycle Life

Replacing organic liquid electrolyte with inorganic solid electrolytes (SE) can potentially address the inherent safety problems in conventional rechargeable batteries. However, solid‐state batteries (SSBs) have been plagued by the relatively low ionic conductivity of SEs and large charge‐transfer resistance between electrode and SE. Here, a new design strategy is reported for improving the ionic conductivity of SE by self‐forming a composite material. An optimized Na⁺ ion conducting composite electrolyte derived from the Na_{1+ n} Zr₂Si _n P_{3? n} O₁₂ NASICON (Na Super Ionic Conductor) structure is successfully synthesized, yielding ultrahigh ionic conductivity of 3.4 mS cm^?1 at 25 °C and 14 mS cm^?1 at 80 °C. On the other hand, in order to enhance the charge‐transfer rate at the electrode/electrolyte interface, an interface modification strategy is demonstrated by utilization of a small amount of nonflammable and nonvolatile ionic liquid (IL) at the cathode side in SSBs. The IL acts as a wetting agent, enabling a favorable interface kinetic in SSBs. The Na₃V₂(PO₄)₃/IL/SE/Na SSB exhibits excellent cycle performance and rate capability. A specific capacity of ≈90 mA h g^?1 is maintained after 10 000 cycles without capacity decay under 10 C rate at room temperature. This provides a new perspective to design fast ion conductors and fabricate long life SSBs.     

An Air‐Stable Densely Packed Phosphorene–Graphene Composite Toward Advanced Lithium Storage Properties

Phosphorene, monolayer or few‐layer black phosphorus (BP), has recently triggered strong scientific interest for lithium/sodium ion batteries (LIBs/SIBs) applications. However, there are still challenges regarding large‐scale fabrication, poor air stability. Herein, we report the high‐yield synthesis of phosphorene with good crystallinity and tunable size distributions via liquid‐phase exfoliation of bulk BP in formamide. Afterwards, a densely packed phosphorene–graphene composite (PG‐SPS, a packing density of 0.6 g cm^?3) is prepared by a simple and easily up‐scalable spark plasma sintering (SPS) process. When working as anode materials of LIBs, PG‐SPS exhibit much improved first‐cycle Coloumbic efficiency (60.2%) compared to phosphorene (11.5%) and loosely stacked phosphorene–graphene composite (34.3%), high specific capacity (1306.7 mAh g^?1) and volumetric capacity (256.4 mAh cm^?3), good rate capabilities (e.g., 415.0 mAh g^?1 at 10 A g^?1) as well as outstanding long‐term cycling life (91.9% retention after 800 cycles at 10 A g^?1). Importantly, excellent air stability of PG‐SPS over the 60 days observation in maintaining its high Li storage properties can be achieved. On the contrary, 95.2% of BP in PG sample was oxidized after only 10 days exposure to ambience, leading to severe degradation of electrochemical properties.