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.     

Viscoelastic and Nonflammable Interface Design–Enabled Dendrite‐Free and Safe Solid Lithium Metal Batteries

Herein, a composite polymer electrolyte with a viscoelastic and nonflammable interface is designed to handle the contact issue and preclude Li dendrite formation. The composite polymer electrolyte (cellulose acetate/polyethylene glycol/Li_1.4Al_0.4Ti_1.6P₃O₁₂) exhibits a wide electrochemical window of 5 V (vs Li⁺/Li), a high Li⁺ transference number of 0.61, and an excellent ionic conductivity of above 10^?4 S cm^?1 at 60 °C. In particular, the intimate contact, low interfacial impedance, and fast ion‐transport process between the electrodes and solid electrolytes can be simultaneously achieved by the viscoelastic and nonflammable layer. Benefiting from this novel design, solid lithium metal batteries with either LiFePO₄ or LiCoO₂ as cathode exhibit superior cyclability and rate capability, such as a discharge capacity of 157 mA h g^?1 after 100 cycles at C/2 and 97 mA h g^?1 at 5C for LiFePO₄ cathode. Moreover, the smooth and uniform Li surface after long‐term cycling confirms the successful suppression of dendrite formation. The viscoelastic and nonflammable interface modification of solid electrolytes provides a promising and general strategy to handle the interfacial issues and improves the operative safety of solid lithium metal batteries.     

Ultrathin Li4Ti5O12 Nanosheet Based Hierarchical Microspheres for High‐Rate and Long‐Cycle Life Li‐Ion Batteries

Ultrathin Li₄Ti₅O₁₂ nanosheet based hierarchical microspheres are synthesized through a three‐step hydrothermal procedure. The average thickness of the Li₄Ti₅O₁₂ sheets is only ≈(6.6 ± 0.25) nm and the specific surface area of the sample is 178 m² g^?1. When applied into lithium ion batteries as anode materials, the hierarchical Li₄Ti₅O₁₂ microspheres exhibit high specific capacities at high rates (156 mA h g^?1 at 20 C, 150 mA h g^?1 at 50 C) and maintain a capacity of 126 mA h g^?1 after 3000 cycles at 20 C. The results clearly suggest that the utility of hierarchical structures based on ultrathin nanosheets can promote the lithium insertion/extraction reactions in Li₄Ti₅O₁₂. The obtained hierarchical Li₄Ti₅O₁₂ with ultrathin nanosheets and large specific surface area can be perfect anode materials for the lithium ion batteries applied in high power facilities, such as electric vehicles and hybrid electric vehicles.     

Hierarchical NiCo2S4@NiO Core–Shell Heterostructures as Catalytic Cathode for Long‐Life Li‐O2 Batteries

The critical challenges of Li‐O₂ batteries lie in sluggish oxygen redox kinetics and undesirable parasitic reactions during the oxygen reduction reaction and oxygen evolution reaction processes, inducing large overpotential and inferior cycle stability. Herein, an elaborately designed 3D hierarchical heterostructure comprising NiCo₂S₄@NiO core–shell arrays on conductive carbon paper is first reported as a freestanding cathode for Li‐O₂ batteries. The unique hierarchical array structures can build up multidimensional channels for oxygen diffusion and electrolyte impregnation. A built‐in interfacial potential between NiCo₂S₄ and NiO can drastically enhance interfacial charge transfer kinetics. According to density functional theory calculations, intrinsic LiO₂‐affinity characteristics of NiCo₂S₄ and NiO play an importantly synergistic role in promoting the formation of large peasecod‐like Li₂O₂, conducive to construct a low‐impedance Li₂O₂/cathode contact interface. As expected, Li‐O₂ cells based on NiCo₂S₄@NiO electrode exhibit an improved overpotential of 0.88 V, a high discharge capacity of 10 050 mAh g^?1 at 200 mA g^?1, an excellent rate capability of 6150 mAh g^?1 at 1.0 A g^?1, and a long‐term cycle stability under a restricted capacity of 1000 mAh g^?1 at 200 mA g^?1. Notably, the reported strategy about heterostructure accouplement may pave a new avenue for the effective electrocatalyst design for Li‐O₂ batteries.     

Uniform Pomegranate‐Like Nanoclusters Organized by Ultrafine Transition Metal Oxide@Nitrogen‐Doped Carbon Subunits with Enhanced Lithium Storage Properties

Uniform pomegranate‐like nanoclusters (NCs) organized by ultrafine transition metal oxide@nitrogen‐doped carbon (TMO@N–C) subunits (diameter ≈ 4 nm) are prepared on a large scale for the first time through a facile, novel, and one‐pot approach. Taking pomegranate‐like Fe₃O₄@N–C NCs as an example, this unique structure provides short Li⁺/electron diffusion pathways for electrochemical reactions, structural stability during cycling, and high electrical conductivity, leading to superior electrochemical performance. The resulting pomegranate‐like Fe₃O₄@N–C NCs possess a high specific capacity (1204.3 mA h g^?1 at 0.5 A g^?1 over 100 cycles), a stable cycle life (1063.0 mA h g^?1 at 1 A g^?1, 98.4% retention after 1000 cycles), and excellent rate capacities (606.0 mA h g^?1 at 10 A g^?1, 92.0% retention; 417.1 mA h g^?1 at 20 A g^?1, 91.7% retention after 1000 cycles).     

Enhanced Cyclability of Lithium–Oxygen Batteries with Electrodes Protected by Surface Films Induced via In Situ Electrochemical Process

Although the rechargeable lithium–oxygen (Li–O₂) batteries have extremely high theoretical specific energy, the practical application of these batteries is still limited by the instability of their carbon‐based air‐electrode, Li metal anode, and electrodes, toward reduced oxygen species. Here a simple one‐step in situ electrochemical precharging strategy is demonstrated to generate thin protective films on both carbon nanotubes (CNTs), air‐electrodes and Li metal anodes simultaneously under an inert atmosphere. Li–O₂ cells after such pretreatment demonstrate significantly extended cycle life of 110 and 180 cycles under the capacity‐limited protocol of 1000 mA h g^?1 and 500 mA h g^?1, respectively, which is far more than those without pretreatment. The thin‐films formed from decomposition of electrolyte during in situ electrochemical precharging processes in an inert environment, can protect both CNTs air‐electrode and Li metal anode prior to conventional Li–O₂ discharge/charge cycling, where reactive reduced oxygen species are formed. This work provides a new approach for protection of carbon‐based air‐electrodes and Li metal anodes in practical Li–O₂ batteries, and may also be applied to other battery systems.     

Enabling High‐Energy Solid‐State Batteries with Stable Anode Interphase by the Use of Columnar Silicon Anodes

All‐solid‐state batteries (ASSBs) with silicon anodes are promising candidates to overcome energy limitations of conventional lithium‐ion batteries. However, silicon undergoes severe volume changes during cycling leading to rapid degradation. In this study, a columnar silicon anode (col‐Si) fabricated by a scalable physical vapor deposition process (PVD) is integrated in all‐solid‐state batteries based on argyrodite‐type electrolyte (Li₆PS₅Cl, 3 mS cm^?1) and Ni‐rich layered oxide cathodes (LiNi_0.9Co_0.05Mn_0.05O₂, NCM) with a high specific capacity (210 mAh g^?1). The column structure exhibits a 1D breathing mechanism similar to lithium, which preserves the interface toward the electrolyte. Stable cycling is demonstrated for more than 100 cycles with a high coulombic efficiency (CE) of 99.7–99.9% in full cells with industrially relevant areal loadings of 3.5 mAh cm^?2, which is the highest value reported so far for ASSB full cells with silicon anodes. Impedance spectroscopy revealed that anode resistance is drastically reduced after first lithiation, which allows high charging currents of 0.9 mA cm^?2 at room temperature without the occurrence of dendrites and short circuits. Finally, in‐operando monitoring of pouch cells gave valuable insights into the breathing behavior of the solid‐state cell.     

An Open‐Structured Matrix as Oxygen Cathode with High Catalytic Activity and Large Li2O2 Accommodations for Lithium–Oxygen Batteries

The nonaqueous lithium–oxygen (Li–O₂) battery is considered as one of the most promising candidates for next‐generation energy storage systems because of its very high theoretical energy density. However, its development is severely hindered by large overpotential and limited capacity, far less than theory, caused by sluggish oxygen redox kinetics, pore clogging by solid Li₂O₂ deposition, inferior Li₂O₂/cathode contact interface, and difficult oxygen transport. Herein, an open‐structured Co₉S₈ matrix with sisal morphology is reported for the first time as an oxygen cathode for Li–O₂ batteries, in which the catalyzing for oxygen redox, good Li₂O₂/cathode contact interface, favorable oxygen evolution, and a promising Li₂O₂ storage matrix are successfully achieved simultaneously, leading to a significant improvement in the electrochemical performance of Li–O₂ batteries. The intrinsic oxygen‐affinity revealed by density functional theory calculations and superior bifunctional catalytic properties of Co₉S₈ electrode are found to play an important role in the remarkable enhancement in specific capacity and round‐trip efficiency for Li–O₂ batteries. As expected, the Co₉S₈ electrode can deliver a high discharge capacity of ≈6875 mA h g^?1 at 50 mA g^?1 and exhibit a low overpotential of 0.57 V under a cutoff capacity of 1000 mA h g^?1, outperforming most of the current metal‐oxide‐based cathodes.     

Fe2O3 Nanoparticle Seed Catalysts Enhance Cyclability on Deep (Dis)charge in Aprotic LiO2 Batteries

Although the high energy density of Li?O₂ chemistry is promising for vehicle electrification, the poor stability and parasitic reactions associated with carbon‐based cathodes and the insulating nature of discharge products limit their rechargeability and energy density. In this study, a cathode material consisting of α‐Fe₂O₃ nanoseeds and carbon nanotubes (CNT) is presented, which achieves excellent cycling stability on deep (dis)charge with high capacity. The initial capacity of Fe₂O₃/CNT electrode reaches 805 mA h g^?1 (0.7 mA h cm^?2) at 0.2 mA cm^?2, while maintaining a capacity of 1098 mA h g^?1 (0.95 mA h cm^?2) after 50 cycles. The operando structural, spectroscopic, and morphological analysis on the evolution of Li₂O₂ indicates preferential Li₂O₂ growth on the Fe₂O₃. The similar d‐spacing of the (100) Li₂O₂ and (104) Fe₂O₃ planes suggest that the latter epitaxially induces Li₂O₂ nucleation. This results in larger Li₂O₂ primary crystallites and smaller secondary particles compared to that deposited on CNT, which enhances the reversibility of the Li₂O₂ formation and leads to more stable interfaces within the electrode. The mechanistic insights into dual‐functional materials that act both as stable host substrates and promote redox reactions in Li?O₂ batteries represent new opportunities for optimizing the discharge product morphology, leading to high cycling stability and coulombic efficiency.     

Direct Growth of Flower‐Like δ‐MnO2 on Three‐Dimensional Graphene for High‐Performance Rechargeable Li‐O2 Batteries

A challenge still remains to develop high‐performance and cost‐effective air electrode for Li‐O₂ batteries with high capacity, enhanced rate capability and long cycle life (100 times or above) despite recent advances in this field. In this work, a new design of binder‐free air electrode composed of three‐dimensional (3D) graphene (G) and flower‐like δ‐MnO₂ (3D‐G‐MnO₂) has been proposed. In this design, graphene and δ‐MnO₂ grow directly on the skeleton of Ni foam that inherits the interconnected 3D scaffold of Ni foam. Li‐O₂ batteries with 3D‐G‐MnO₂ electrode can yield a high discharge capacity of 3660 mAh g^?1 at 0.083 mA cm^?2. The battery can sustain 132 cycles at a capacity of 492 mAh g^?1 (1000 mAh g_carbon ^?1) with low overpotentials under a high current density of 0.333 mA cm^?2. A high average energy density of 1350 Wh Kg^?1 is maintained over 110 cycles at this high current density. The excellent catalytic activity of 3D‐G‐MnO₂ makes it an attractive air electrode for high‐performance Li‐O₂ batteries.     

Fe2O3 Nanoparticle Seed Catalysts Enhance Cyclability on Deep (Dis)charge in Aprotic Li?O2 Batteries

Although the high energy density of Li? O₂ chemistry is promising for vehicle electrification, the poor stability and parasitic reactions associated with carbon‐based cathodes and the insulating nature of discharge products limit their rechargeability and energy density. In this study, a cathode material consisting of α‐Fe₂O₃ nanoseeds and carbon nanotubes (CNT) is presented, which achieves excellent cycling stability on deep (dis)charge with high capacity. The initial capacity of Fe₂O₃/CNT electrode reaches 805 mA h g^?1 (0.7 mA h cm^?2) at 0.2 mA cm^?2, while maintaining a capacity of 1098 mA h g^?1 (0.95 mA h cm^?2) after 50 cycles. The operando structural, spectroscopic, and morphological analysis on the evolution of Li₂O₂ indicates preferential Li₂O₂ growth on the Fe₂O₃. The similar d‐spacing of the (100) Li₂O₂ and (104) Fe₂O₃ planes suggest that the latter epitaxially induces Li₂O₂ nucleation. This results in larger Li₂O₂ primary crystallites and smaller secondary particles compared to that deposited on CNT, which enhances the reversibility of the Li₂O₂ formation and leads to more stable interfaces within the electrode. The mechanistic insights into dual‐functional materials that act both as stable host substrates and promote redox reactions in Li? O₂ batteries represent new opportunities for optimizing the discharge product morphology, leading to high cycling stability and coulombic efficiency.     

Solvent‐Free Synthesis of Thin,Flexible, Nonflammable Garnet‐Based Composite Solid Electrolyte for All‐Solid‐State Lithium Batteries

Thin solid‐state electrolytes with nonflammability, high ionic conductivity, low interfacial resistance, and good processability are urgently required for next‐generation safe, high energy density lithium metal batteries. Here, a 3D Li_6.75La₃Zr_1.75Ta_0.25O₁₂ (LLZTO) self‐supporting framework interconnected by polytetrafluoroethylene (PTFE) binder is prepared through a simple grinding method without any solvent. Subsequently, a garnet‐based composite electrolyte is achieved through filling the flexible 3D LLZTO framework with a succinonitrile solid electrolyte. Due to the high content of garnet ceramic (80.4 wt%) and high heat‐resistance of the PTFE binder, such a composite electrolyte film with nonflammability and high processability exhibits a wide electrochemical window of 4.8 V versus Li/Li⁺ and high ionic transference number of 0.53. The continuous Li⁺ transfer channels between interconnected LLZTO particles and succinonitrile, and the soft electrolyte/electrode interface jointly contribute to a high ambient‐temperature ionic conductivity of 1.2 × 10^?4 S cm^?1 and excellent long‐term stability of the Li symmetric battery (stable at a current density of 0.1 mA cm^?2 for over 500 h). Furthermore, as‐prepared LiFePO₄|Li and LiNi_0.5Mn_0.3Co_0.2O₂|Li batteries based on the thin composite electrolyte exhibit high discharge specific capacities of 153 and 158 mAh g^?1 respectively, and desirable cyclic stabilities at room temperature.     

Li+ Pre‐Insertion Leads to Formation of Solid Electrolyte Interface on TiO2 Nanotubes That Enables High‐Performance Anodes for Sodium Ion Batteries

Recently, sodium ion batteries (SIBs) have been widely investigated as one of the most promising candidates for replacing lithium ion batteries (LIBs). For SIBs or LIBs, designing a stable and uniform solid electrolyte interphase (SEI) at the electrode–electrolyte interface is the key factor to provide high capacity, long‐term cycling, and high‐rate performance. In this paper, it is described how a remarkably enhanced SEI layer can be obtained on TiO₂ nanotube (TiO₂ NTs) arrays that allows for a strongly improved performance of sodium battery systems. Key is that a Li⁺ pre‐insertion in TiO₂ NTs can condition the SEI for Na⁺ replacement. SIBs constructed with Li‐pre‐inserted NTs deliver an exceptional Na⁺ cycling stability (e.g., 99.9 ± 0.1% capacity retention during 250 cycles at a current rate of 50 mA g^?1) and an excellent rate capability (e.g., 132 mA h g^?1 at a current rate of 1 A g^?1). The key factor in this outstanding performance is that Li‐pre‐insertion into TiO₂ NTs leads not only to an enhanced electronic conductivity in the tubes, but also expands the anatase lattice for facilitated subsequent Na⁺ cycling.     

High‐Performance All‐Solid‐State Lithium–Sulfur Batteries Enabled by Amorphous Sulfur‐Coated Reduced Graphene Oxide Cathodes

Safety and the polysulfide shuttle reaction are two major challenges for liquid electrolyte lithium–sulfur (Li–S) batteries. Although use of solid‐state electrolytes can overcome these two challenges, it also brings new challenges by increasing the interface resistance and stress/strain. In this work, the interface resistance and stress/strain of sulfur cathodes are significantly reduced by conformal coating ≈2 nm sulfur (S) onto reduced graphene oxide (rGO). An Li–S full cell consisting of an rGO@S‐Li₁₀GeP₂S₁₂‐acetylene black (AB) composite cathode is evaluated. At 60 °C, the all‐solid‐state Li–S cell demonstrates a similar electrochemical performance as in liquid organic electrolyte, with high rate capacities of 1525.6, 1384.5, 1336.3, 903.2, 502.6, and 204.7 mA h g^?1 at 0.05, 0.1, 0.5, 1.0, 2.0, and 5.0 C, respectively. It can maintain a high and reversible capacity of 830 mA h g^?1 at 1.0 C for 750 cycles. The uniform distribution of the rGO@S nanocomposite in the Li₁₀GeP₂S₁₂‐AB matrix generates uniform volume changes during lithiation/delithiation, significantly reducing the stress/strain, thus extending the cycle life. Minimization of the stress/strain of solid cells is the key for a long cycle life of all‐solid‐state Li–S batteries.     

A Lithium Amide‐Borohydride Solid‐State Electrolyte with Lithium‐Ion Conductivities Comparable to Liquid Electrolytes

High ionic conductivity of up to 6.4 × 10^?3 S cm^?1 near room temperature (40 °C) in lithium amide‐borohydrides is reported, comparable to values of liquid organic electrolytes commonly employed in lithium‐ion batteries. Density functional theory is applied coupled with X‐ray diffraction, calorimetry, and nuclear magnetic resonance experiments to shed light on the conduction mechanism. A Li₄Ti₅O₁₂ half‐cell battery incorporating the lithium amide‐borohydride electrolyte exhibits good rate performance up to 3.5 mA cm^?2 (5 C) and stable cycling over 400 cycles at 1 C at 40 °C, indicating high bulk and interfacial stability. The results demonstrate the potential of lithium amide‐borohydrides as solid‐state electrolytes for high‐power lithium‐ion batteries.     

Nanoparticles Encapsulated in Porous Carbon Matrix Coated on Carbon Fibers: An Ultrastable Cathode for Li‐Ion Batteries

Nanostructured V₂O₅ is emerging as a new cathode material for lithium ion batteries for its distinctly high theoretic capacity over the current commercial cathodes. The main challenges associated with nanostructured V₂O₅ cathodes are structural degradation, instability of the solid‐electrolyte interface layer, and poor electron conductance, which lead to low capacity and rapid decay of cyclic stability. Here, a novel composite structure of V₂O₅ nanoparticles encapsulated in 3D networked porous carbon matrix coated on carbon fibers (V₂O₅/3DC‐CFs) is reported that effectively addresses the mentioned problems. Remarkably, the V₂O₅/3DC‐CF electrode exhibits excellent overall lithium‐storage performance, including high Coulombic efficiency, excellent specific capacity, outstanding cycling stability and rate property. A reversible capacity of ≈183 mA h g^?1 is obtained at a high current density of 10 C, and the battery retains 185 mA h g^?1 after 5000 cycles, which shows the best cycling stability reported to date among all reported cathodes of lithium ion batteries as per the knowledge. The outstanding overall properties of the V₂O₅/3DC‐CF composite make it a promising cathode material of lithium ion batteries for the power‐intensive energy storage applications.     

MnMoO4 Electrocatalysts for Superior Long‐Life and High‐Rate Lithium‐Oxygen Batteries

Lithium‐oxygen batteries represent a significant scientific challenge for high‐rate and long‐term cycling using oxygen electrodes that contain efficient electrocatalysts. The mixed transition metal oxide catalysts provide the most efficient catalytic activity for partial heterogeneous surface cations with oxygen vacancies as the active phase. They include multiple oxidation states and oxygen vacancies. Here, using a combination of transmission electron microscopy, differential electrochemical mass spectrometry, X‐ray photoelectron spectroscopy, and electrochemical properties to probe the surface of the MnMoO₄ nanowires, it is shown that the intrinsic MnMoO₄ oxygen vacancies on the oxygen electrode are an effective strategy to achieve a high reversibility and high efficiency for lithium‐oxygen (Li‐O₂) batteries. The modified MnMoO₄ nanowires exhibit a highly stable capacity at a fixed capacity of 5000 mA h g_sp^?1 (calculated weight of Super P carbon black) during 50 cycles, a high‐rate capability at a current rate of 3000 mA g_sp^?1 during 70 cycles, and a long‐term reversible capacity during 188 cycles at a fixed capacity of 1000 mA h g_sp^?1. It is demonstrated that this strategy for creating mixed transition metal oxides (e.g., MnMoO₄) may pave the way for the new structural design of electrocatalysts for Li‐O₂ batteries.     

Hydrogenated Core–Shell MAX@K2Ti8O17 Pseudocapacitance with Ultrafast Sodium Storage and Long‐Term Cycling

Sodium‐ion batteries are considered alternatives to lithium‐ion batteries for energy storage devices due to their competitive cost and source abundance. However, the development of electrode materials with long‐term stability and high capacity remains a great challenge. Here, this paper describes for the first time the synthesis of a new class of core–shell MAX@K₂Ti₈O₁₇ by alkaline hydrothermal reaction and hydrogenation of MAX, which grants high sodium ion‐intercalation pseudocapacitance. This composite electrode displays extraordinary reversible capacities of 190 mA h g^?1 at 200 mA g^?1 (0.9 C, theoretical value of ≈219 mA h g^?1) and 150 mA h g^?1 at 1000 mA g^?1 (4.6 C). More importantly, a reversible capacity of 75 mA h g^?1 at 10 000 mA g^?1 (46 C) is retained without any apparent capacity decay even after more than 10 000 cycles. Experimental tests and first‐principle calculations confirm that the increase in Ti³⁺ on the surface layers of MAX@K₂Ti₈O₁₇ by hydrogenation increases its conductivity in addition to enhancing the sodium‐ion intercalation pseudocapacitive process. Furthermore, the distorted dodecahedrons between Ti and O layers not only provide abundant sites for sodium‐ion accommodation but also act as wide tunnels for sodium‐ion transport.     

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.     

Sulfur‐Embedded Activated Multichannel Carbon Nanofiber Composites for Long‐Life,High‐Rate Lithium–Sulfur Batteries

Despite the 3–5 fold higher energy density than the conventional Li‐ion cells at a lower cost, commercialization of Li–S batteries is hindered by the insulating nature of sulfur and the dissolution of intermediate polysulfides (Li₂S _X , 4 < X ≤ 8) into the electrolyte. The authors demonstrate here multichannel carbon nanofibers that are composed of parallel mesoporous channels connected with micropores as sulfur containment. In addition, hydroxyl functional groups are formed on the carbon surface through a chemical activation to enhance the interaction between sulfur and carbon. In the sulfur embedded composite, the mesoporous multichannel enhances the active material utilization and sulfur loading, while the micropores act as a reaction chamber for sulfur component and trap site for polysulfide with the assistance of the functional groups. This sulfur–carbon composite electrode with 2.2 mg cm^?2 sulfur displays excellent performance with high rate capability (initial capacity of 1351 mA h g^?1 at C/5 rate and 847 mA h g^?1 at 5C rate), maintaining 920 mA h g^?1 even after 300 cycles (a decay of 0.07% per cycle). Furthermore, a stable reversible capacity of as high as ≈1100 mA h g^?1 is realized with a higher sulfur loading of 4.6 mg cm^?2.