Molecular Engineering of Monodisperse SnO2 Nanocrystals Anchored on Doped Graphene with High‐Performance Lithium/Sodium‐Storage Properties in Half/Full Cells

The fabrication of ultrasmall and high‐content SnO₂ nanocrystals anchored on doped graphene can endow SnO₂ with superior electrochemical properties. Herein, an effective strategy, involving molecular engineering of a layer‐by‐layer assembly technique, is proposed to homogeneously anchor SnO₂ nanocrystals on nitrogen/sulfur codoped graphene (NSGS), which serves as an advanced anode material in lithium/sodium‐ion batteries (LIBs/SIBs). Benefiting from novel design and specific structure, the optimized NSGS for LIBs displays high initial capacity (2123.9 mAh g^?1 at 0.1 A g^?1), long‐term cycling performance (only 0.8% loss after 500 cycles), and good rate capability (477.4 mAh g^?1 at 5 A g^?1). In addition, the optimized NSGS for SIBs also delivers high initial capacity (791.7 mAh g^?1 at 0.1 A g^?1) and high reversible capacity (180.2 mAh g^?1 after 500 cycles at 0.5 A g^?1). Meanwhile, based on the detailed analysis of phase transition and electrochemical reaction kinetics, the reaction mechanisms of NSGS in LIBs and SIBs as well as the distinction in LIBs/SIBs are clearly articulated. Notably, to further explore the practical application, Li/Na⁺ full cells are also assembled by coupling the optimized NSGS anode with LiCoO₂ and Na₃V₂(PO₄)₃/C cathodes, respectively.     

Grafting Benzenediazonium Tetrafluoroborate onto LiNixCoyMnzO2 Materials Achieves Subzero‐Temperature High‐Capacity Lithium‐Ion Storage via a Diazonium Soft‐Chemistry Method

Subzero‐temperature Li‐ion batteries (LIBs) are highly important for specific energy storage applications. Although the nickel‐rich layered lithium transition metal oxides(LiNi_xCo_yMn_zO₂) (LNCM) (x > 0.5, x + y +z = 1) are promising cathode materials for LIBs, their very slow Li‐ion diffusion is a main hurdle on the way to achieve high‐performance subzero‐temperature LIBs. Here, a class of low‐temperature organic/inorganic hybrid cathode materials for LIBs, prepared by grafting a conducting polymer coating on the surface of 3 µm sized LiNi_0.6Co_0.2Mn_0.2O₂ (LNCM‐3) material particles via a greener diazonium soft‐chemistry method is reported. Specifically, LNCM‐3 particles are uniformly coated with a thin polyphenylene film via the spontaneous reaction between LNCM‐3 and C₆H₅N₂⁺BF₄^?. Compared with the uncoated one, the polyphenylene‐coated LNCM‐3 (polyphenylene/LNCM‐3) has shown much improved low‐temperature discharge capacity (≈148 mAh g^?1 at 0.1 C, ?20 °C), outstanding rate capability (≈105 mAh g^?1 at 1 C, ?20 °C), and superior low‐temperature long‐term cycling stability (capacity retention is up to 90% at 0.5 C over 1150 cycles). The low‐temperature performance of polyphenylene/LNCM‐3 is the best among the reported state‐of‐the art cathode materials for LIBs. The present strategy opens up a new avenue to construct advanced cathode materials for wider range applications.     

Ice Templated Free‐Standing Hierarchically WS2/CNT‐rGO Aerogel for High‐Performance Rechargeable Lithium and Sodium Ion Batteries

A hybrid nanoarchitecture aerogel composed of WS₂ nanosheets and carbon nanotube‐reduced graphene oxide (CNT‐rGO) with ordered microchannel three‐dimensional (3D) scaffold structure was synthesized by a simple solvothermal method followed by freeze‐drying and post annealing process. The 3D ordered microchannel structures not only provide good electronic transportation routes, but also provide excellent ionic conductive channels, leading to an enhanced electrochemical performance as anode materials both for lithium‐ion batteries (LIBs) and sodium‐ion batteries (SIBs). Significantly, WS₂/CNT‐rGO aerogel nanostructure can deliver a specific capacity of 749 mA h g^?1 at 100 mA g^?1 and a high first‐cycle coulombic efficiency of 53.4% as the anode material of LIBs. In addition, it also can deliver a capacity of 311.4 mA h g^?1 at 100 mA g^?1, and retain a capacity of 252.9 mA h g^?1 at 200 mA g^?1 after 100 cycles as the anode electrode of SIBs. The excellent electrochemical performance is attributed to the synergistic effect between the WS₂ nanosheets and CNT‐rGO scaffold network and rational design of 3D ordered structure. These results demonstrate the potential applications of ordered CNT‐rGO aerogel platform to support transition‐metal‐dichalcogenides (i.e., WS₂) for energy storage devices and open up a route for material design for future generation energy storage devices.     

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.     

Enhanced Li‐Ion Accessibility in MXene Titanium Carbide by Steric Chloride Termination

Pseudocapacitance is a key charge storage mechanism to advanced electrochemical energy storage devices distinguished by the simultaneous achievement of high capacitance and a high charge/discharge rate by using surface redox chemistries. MXene, a family of layered compounds, is a pseudocapacitor‐like electrode material which exhibits charge storage through exceptionally fast ion accessibility to redox sites. Here, the authors demonstrate steric chloride termination in MXene Ti₂CT_x (T_x : surface termination groups) to open the interlayer space between the individual 2D Ti₂CT_x units. The open interlayer space significantly enhances Li‐ion accessibility, leading to high gravimetric and volumetric capacitances (300 F g^?1 and 130 F cm^?3) with less diffusion limitation. A Li‐ion hybrid capacitor consisting of the Ti₂CT_x negative electrode and the LiNi_1/3Co_1/3Mn_1/3O₂ positive electrode displays an unprecedented specific energy density of 160 W h kg^?1 at 220 W kg^?1 based on the total weight of positive and negative active materials.     

Vertically Aligned Sn4+ Preintercalated Ti2CTX MXene Sphere with Enhanced Zn Ion Transportation and Superior Cycle Lifespan

While 2D MXenes have been widely used in energy storage systems, surface barriers induced by restacking of nanosheets and the limited kinetics resulting from insufficient interlayer spacing are two unresolved issues. Here an Sn⁴⁺ preintercalated Ti₂CT_X with effectively enlarged interlayer spacing is synthesized. The preintercalated Ti₂CT_X is aligned on a carbon sphere to further enhance ion transportation by shortening the ion diffusion path and enhancing the reaction kinetics. As a result, when paired with a Zn anode, 12 500 cycles, which equals 2 800 h cycle time, and 5% capacity fluctuation are obtained, surpassing all reported MXene‐based aqueous electrodes. At 0.1 A g^‐1, the capacity reaches 138 mAh g^‐1, and 92 mAh g^‐1 remains even at 5 A g^‐1. In addition, the low anti‐self‐discharge rate of 0.989 mV h^‐1 associated with a high capacity retention of 80.5% over 548 h is obtained. Moreover, the fabricated quasi‐solid capacitor based on a hydrogel film electrolyte exhibits good mechanical deformation and weather resistance. This work employs both preintercalation and alignment to MXene and achieves enhanced ion diffusion kinetics in an aqueous zinc ion capacitors (ZICs) system, which may be applied to other MXene batteries for enhanced performance.     

Lithium‐Pretreated Hard Carbon as High‐Performance Sodium‐Ion Battery Anodes

Hard carbon (HC) is the state‐of‐the‐art anode material for sodium‐ion batteries (SIBs). However, its performance has been plagued by the limited initial Coulombic efficiency (ICE) and mediocre rate performance. Here, experimental and theoretical studies are combined to demonstrate the application of lithium‐pretreated HC (LPHC) as high‐performance anode materials for SIBs by manipulating the solid electrolyte interphase in tetraglyme (TEGDME)‐based electrolyte. The LPHC in TEGDME can 1) deliver > 92% ICE and ≈220 mAh g^?1 specific capacity, twice of the capacity (≈100 mAh g^?1) in carbonate electrolyte; 2) achieve > 85% capacity retention over 1000 cycles at 1000 mA g^?1 current density (4 C rate, 1 C = 250 mA g^?1) with a specific capacity of ≈150 mAh g^?1, ≈15 times of the capacity (10 mAh g^?1) in carbonate. The full cell of Na₃V₂(PO₄)₃‐LPHC in TEGDME demonstrated close to theoretical specific capacity of ≈98 mAh g^?1 based on Na₃V₂(PO₄)₃ cathode, ≈2.5 times of the value (≈40 mAh g^?1) with nontreated HC. This work provides new perception on the anode development for SIBs.     

Achieving High Pseudocapacitance of 2D Titanium Carbide (MXene) by Cation Intercalation and Surface Modification

Supercapacitors attract great interest because of the increasing and urgent demand for environment‐friendly high‐power energy sources. Ti₃C₂, a member of MXene family, is a promising electrode material for supercapacitors owing to its excellent chemical and physical properties. However, the highest gravimetric capacitance of the MXene‐based electrodes is still relatively low (245 F g^?1) and the key challenge to improve this is to exploit more pseudocapacitance by increasing the active site concentration. Here, a method to significantly improve the gravimetric capacitance of Ti₃C₂T_x MXenes by cation intercalation and surface modification is reported. After K⁺ intercalation and terminal groups (OH^?/F^?) removing , the intercalation pseudocapacitance is three times higher than the pristine MXene, and MXene sheets exhibit a significant enhancement (about 211% of the origin) in the gravimetric capacitance (517 F g^?1 at a discharge rate of 1 A g^?1). Moreover, the as‐prepared electrodes show above 99% retention over 10 000 cycles. This improved electrochemical performance is attributed to the large interlayer voids of Ti₃C₂ and lowest terminated surface group concentration. This study demonstrates a new strategy applicable to other MXenes (Ti₂CT_x , Nb₂CT_x , etc.) in maximizing their potential applications in energy storage.     

Template‐Free Construction of Self‐Supported Sb Prisms with Stable Sodium Storage

Antimony (Sb) is a promising anode material for sodium‐ion batteries owing to its large capacity of 660 mAh g^?1. However, its practical application is restricted by the rapid capacity decay resulted from a large volume expansion up to 390% upon Na alloying. Herein, construction of a self‐supported Sb array that has enough space allowing for effective accommodation of the volume change is reported. The array of Sb prisms is directly grown on a Cu substrate via a template‐free electrodeposition, followed by mild heating to consolidate the structural integrity between Sb and Cu. The resulting 3D architecture endows the Sb array with excellent sodium storage performance, exhibiting a reversible capacity of 578 mAh g^?1 and retaining 531 mAh g^?1 over 100 cycles at 0.5 C. The potential of Sb array in sodium‐ion full cells by pairing it with a Na_0.67(Ni_0.23Mg_0.1Mn_0.67)O₂ cathode is further demonstrated. This full cell affords a specific energy of 197 Wh kg^?1 at 0.2 C and a specific power of 1280 W kg^?1 at 5 C. Considering its low cost and scale‐up capability, the template‐free route may find extensive applications in designing electrode architectures.     

Defect‐Rich Soft Carbon Porous Nanosheets for Fast and High‐Capacity Sodium‐Ion Storage

Soft carbon has attracted tremendous attention as an anode in rocking‐chair batteries owing to its exceptional properties including low‐cost, tunable interlayer distance, and favorable electronic conductivity. However, it fails to exhibit decent performance for sodium‐ion storage owing to difficulties in the formation of sodium intercalation compounds. Here, microporous soft carbon nanosheets are developed via a microwave induced exfoliation strategy from a conventional soft carbon compound obtained by pyrolysis of 3,4,9,10‐perylene tetracarboxylic dianhydride. The micropores and defects at the edges synergistically leads to enhanced kinetics and extra sodium‐ion storage sites, which contribute to the capacity increase from 134 to 232 mAh g^?1 and a superior rate capability of 103 mAh g^?1 at 1000 mA g^?1 for sodium‐ion storage. In addition, the capacitance‐dominated sodium‐ion storage mechanism is identified through the kinetics analysis. The in situ X‐ray diffraction analyses are used to reveal that sodium ions intercalate into graphitic layers for the first time. Furthermore, the as‐prepared nanosheets can also function as an outstanding anode for potassium‐ion storage (reversible capacity of 291 mAh g^?1) and dual‐ion full cell (cell‐level capacity of 61 mAh g^?1 and average working voltage of 4.2 V). These properties represent the potential of soft carbon for achieving high‐energy, high‐rate, and low‐cost energy storage systems.     

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.     

Partially Reduced Holey Graphene Oxide as High Performance Anode for Sodium‐Ion Batteries

The current Na⁺ storage performance of carbon‐based materials is still hindered by the sluggish Na⁺ ion transfer kinetics and low capacity. Graphene and its derivatives have been widely investigated as electrode materials in energy storage and conversion systems. However, as anode materials for sodium‐ion batteries (SIBs), the severe π–π restacking of graphene sheets usually results in compact structure with a small interlayer distance and a long ion transfer distance, thus leading to low capacity and poor rate capability. Herein, partially reduced holey graphene oxide is prepared by simple H₂O₂ treatment and subsequent low temperature reduction of graphene oxide, leading to large interlayer distance (0.434 nm), fast ion transport, and larger Na⁺ storage space. The partially remaining oxygenous groups can also contribute to the capacity by redox reaction. As anode material for SIBs, the optimized electrode delivers high reversible capacity, high rate capability (365 and 131 mAh g^?1 at 0.1 and 10 A g^?1, respectively), and good cycling performance (163 mAh g^?1 after 3000 cycles at a current density of 2 A g^?1), which is among the best reported performances for carbon‐based SIB anodes.     

A Novel α‐MoO3/Single‐Walled Carbon Nanohorns Composite as High‐Performance Anode Material for Fast‐Charging Lithium‐Ion Battery

Orthorhombic α‐MoO₃ is a potential anode material for lithium‐ion batteries due to its high theoretical capacity of 1100 mAh g^?1 and excellent structural stability. However, its intrinsic poor electronic conductivity and high volume expansion during the charge–discharge process impede it from achieving a high practical capacity. A novel composite of α‐MoO₃ nanobelts and single‐walled carbon nanohorns (SWCNHs) is synthesized by a facile microwave hydrothermal technique and demonstrated as a high‐performance anode material for lithium‐ion batteries. The α‐MoO₃/SWCNH composite displays superior electrochemical properties (654 mAh g^?1 at 1 C), excellent rate capability (275 mAh g^?1 at 5 C), and outstanding cycle life (capacity retention of >99% after 3000 cycles at 1 C) without any cracking of the electrode. The presence of SWCNHs in the composite enhances the electrochemical properties of α‐MoO₃ by acting as a lithium storage material, electronic conductive medium, and buffer against pulverization.     

Rational Design of Hydroxyl‐Rich Ti3C2Tx MXene Quantum Dots for High‐Performance Electrochemical N2 Reduction

To enable an efficient and cost‐effective electrocatalytic N₂ reduction reaction (NRR) the development of an electrocatalyst with a high NH₃ yield and good selectivity is required. In this work, Ti₃C₂T_x MXene‐derived quantum dots (Ti₃C₂T_x QDs) with abundant active sites enable the development of efficient NRR electrocatalysts. Given surface functional groups play a key role on the electrocatalytic performance, density functional theory calculations are first conducted, clarifying that hydroxyl groups on Ti₃C₂T_x offer excellent NRR activity. Accordingly, hydroxyl‐rich Ti₃C₂T_x QDs (Ti₃C₂OH QDs) are synthesized as NRR catalysts by alkalization and intercalation. This material offers an NH₃ yield and Faradaic efficiency of 62.94 µg h^?1 mg^?1_cat. and 13.30% at ?0.50 V, respectively, remarkably higher than reported MXene catalysts. This work demonstrates that MXene catalysts can be mediated through the optimization of both QDs sizes and functional groups for efficient ammonia production at room temperature.     

Capture and Catalytic Conversion of Polysulfides by In Situ Built TiO2‐MXene Heterostructures for Lithium–Sulfur Batteries

The detrimental shuttle effect in lithium–sulfur batteries mainly results from the mobility of soluble polysulfide intermediates and their sluggish conversion kinetics. Herein, presented is a multifunctional catalyst with the merits of strong polysulfides adsorption ability, superior polysulfides conversion activity, high specific surface area, and electron conductivity by in situ crafting of the TiO₂‐MXene (Ti₃C₂T_x) heterostructures. The uniformly distributed TiO₂ on MXene sheets act as capturing centers to immobilize polysulfides, the hetero‐interface ensures rapid diffusion of anchored polysulfides from TiO₂ to MXene, and the oxygen‐terminated MXene surface is endowed with high catalytic activity toward polysulfide conversion. The improved lithium–sulfur batteries deliver 800 mAh g^?1 at 2 C and an ultralow capacity decay of 0.028% per cycle over 1000 cycles at 2 C. Even with a high sulfur loading of 5.1 mg cm^?2, the capacity retention of 93% after 200 cycles is still maintained. This work sheds new insights into the design of high‐performance catalysts with manipulated chemical components and tailored surface chemistry to regulate polysulfides in Li–S batteries.     

Covalent Encapsulation of Sulfur in a MOF‐Derived S,N‐Doped Porous Carbon Host Realized via the Vapor‐Infiltration Method Results in Enhanced Sodium–Sulfur Battery Performance

Practical applications of room temperature sodium–sulfur batteries are still inhibited by the poor conductivity and slow reaction kinetics of sulfur, and dissolution of intermediate polysulfides in the commonly used electrolytes. To address these issues, starting from a novel 3D Zn‐based metal–organic framework with 2,5‐thiophenedicarboxylic acid and 1,4‐bis(pyrid‐4‐yl) benzene as ligands, a S, N‐doped porous carbon host with 3D tubular holes for sulfur storage is fabricated. In contrast to the commonly used melt‐diffusion method to confine sulfur physically, a vapor‐infiltration method is utilized to achieve sulfur/carbon composite with covalent bonds, which can join electrochemical reaction without low voltage activation. A polydopamine derived N‐doped carbon layer is further coated on the composite to confine the high‐temperature‐induced gas‐phase sulfur inside the host. S and N dopants increase the polarity of the carbon host to restrict diffusion of sulfur, and its 3D porous structure provides a large storage area for sulfur. As a result, the obtained composite shows outstanding electrochemical performance with 467 mAh g^?1 (1262 mAh g^?1_(sulfur)) at 0.1 A g^?1, 270 mAh g^?1 (730 mAh g^?1_(sulfur)) after 1000 cycles at 1 A g^?1 and 201 mAh g^?1 (543 mAh g^?1_(sulfur)) at 5.0 A g^?1.     

An Ultrastable Presodiated Titanium Disulfide Anode for Aqueous “Rocking‐Chair” Zinc Ion Battery

Rechargeable aqueous Zn‐based batteries are attractive candidates as energy storage technology, but the uncontrollable Zn dendrites, low stripping/plating coulombic efficiency, and inefficient utilization of Zn metal limit the battery reliability and energy density. Herein, for the first time, a novel presodiated TiS₂ (Na_0.14TiS₂) is proposed and investigated as an intercalated anode for aqueous Zn‐ion batteries, showing a capacity of 140 mAh g^?1 with a suitable potential of 0.3 V (vs Zn²⁺/Zn) at 0.05 A g^?1 and superior cyclability of 77% retention over 5000 cycles at 0.5 A g^?1. The remarkable performance originates from the buffer phase formation of Na_0.14TiS₂ after chemically presodiating TiS₂, which not only improves the structural reversibility and stability but also enhances the diffusion coefficient and electronic conductivity, and lowers cation migration barrier, as evidenced by a series of experimental and theoretical studies. Moreover, an aqueous “rocking‐chair” Zn‐ion full battery is successfully demonstrated by this Na_0.14TiS₂ anode and ZnMn₂O₄ cathode, which delivers a capacity of 105 mAh g^?1 (for anode) with an average voltage of 0.95 V at 0.05 A g^?1 and preserves 74% retention after 100 cycles at 0.2 A g^?1, demonstrating the feasibility of Zn‐ion full batteries for energy storage applications.     

In Situ Synthesis of Hierarchical Core Double‐Shell Ti‐Doped LiMnPO4@NaTi2(PO4)3@C/3D Graphene Cathode with High‐Rate Capability and Long Cycle Life for Lithium‐Ion Batteries

Olivine‐type LiMnPO₄ (LMP) cathodes have gained enormous attraction for Li‐ion batteries (LIBs), thanks to their large theoretical capacity, high discharge platform, and thermal stability. However, it is still hugely challenging to achieve encouraging Li‐storage behaviors owing to their low electronic conductivity and limited lithium diffusion. Herein, the core double‐shell Ti‐doped LMP@NaTi₂(PO₄)₃@C/3D graphene (TLMP@NTP@C/3D‐G) architecture is designed and constructed via an in situ synthetic methodology. A continuous electronic conducting network is formed with the unfolded 3D‐G and conducting carbon nanoshell. The Nasicon‐type NTP nanoshell with exceptional ionic conductivity efficiently inhibits gradual enrichment in by‐products, and renders low surfacial/interfacial electron/ion‐diffusion resistance. Besides, a rapid Li⁺ diffusion in the bulk structure is guaranteed with the reduction of Mn_Li+˙ antisite defects originating from the synchronous Ti‐doping. Benefiting from synergetic contributions from these design rationales, the integrated TLMP@NTP@C/3D‐G cathode yields high initial discharge capacity of ≈164.8 mAh g^?1 at 0.05 C, high‐rate reversible capacity of ≈116.2 mAh g^?1 at 10 C, and long‐term capacity retention of ≈93.3% after 600 cycles at 2 C. More significantly, the electrode design developed here will exert significant impact upon constructing other advanced cathodes for high‐energy/power LIBs.     

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.     

A Highly Reversible Nano‐Si Anode Enabled by Mechanical Confinement in an Electrochemically Activated LixTi4Ni4Si7 Matrix

This paper reports a Si‐Ti‐Ni ternary alloy developed for commercial application as an anode material for lithium ion batteries. Our alloy exhibits a stable capacity above 900 mAh g^?1 after 50 cycles and a high coulombic efficiency of up to 99.7% during cycling. To enable a highly reversible nano‐Si anode, melt spinning is employed to embed nano‐Si particles in a Ti₄Ni₄Si₇ matrix. The Ti₄Ni₄Si₇ matrix fulfills two important purposes. First, it reduces the maximum stress evolved in the nano‐Si particles by applying a compressive stress to mechanically confine Si expansion during lithiation. And second, the Ti₄Ni₄Si₇ matrix is a good mixed conductor that isolates nano‐Si from the liquid electrolyte, thus preventing parasitic reactions responsible for the formation of a solid electrolyte interphase. Given that a coulombic efficiency above 99.5% is rarely reported for Si based anode materials, this alloy's performance suggests a promising new approach to engineering Si anode materials.