Fabrication and Shell Optimization of Synergistic TiO2‐MoO3 Core–Shell Nanowire Array Anode for High Energy and Power Density Lithium‐Ion Batteries

A novel synergistic TiO₂‐MoO₃ (TO‐MO) core–shell nanowire array anode has been fabricated via a facile hydrothermal method followed by a subsequent controllable electrodeposition process. The nano‐MoO₃ shell provides large specific capacity as well as good electrical conductivity for fast charge transfer, while the highly electrochemically stable TiO₂ nanowire core (negligible volume change during Li insertion/desertion) remedies the cycling instability of MoO₃ shell and its array further provides a 3D scaffold for large amount electrodeposition of MoO₃. In combination of the unique electrochemical attributes of nanostructure arrays, the optimized TO‐MO hybrid anode (mass ratio: ca. 1:1) simultaneously exhibits high gravimetric capacity (ca. 670 mAh g^?1; approaching the hybrid's theoretical value), excellent cyclability (>200 cycles) and good rate capability (up to 2000 mA g^?1). The areal capacity is also as high as 3.986 mAh cm^?2, comparable to that of typical commercial LIBs. Furthermore, the hybrid anode was assembled for the first time with commercial LiCoO₂ cathode into a Li ion full cell, which shows outstanding performance with maximum power density of 1086 W kg_total ^?1 (based on the total mass of the TO‐MO and LiCoO₂) and excellent energy density (285 Wh kg_total ^?1) that is higher than many previously reported metal oxide anode‐based Li full cells.     

Optimization of Von Mises Stress Distribution in Mesoporous α‐Fe2O3/C Hollow Bowls Synergistically Boosts Gravimetric/Volumetric Capacity and High‐Rate Stability in Alkali‐Ion Batteries

Hollow structures are often used to relieve the intrinsic strain on metal oxide electrodes in alkali‐ion batteries. Nevertheless, one common drawback is that the large interior space leads to low volumetric energy density and inferior electric conductivity. Here, the von Mises stress distribution on a mesoporous hollow bowl (HB) is simulated via the finite element method, and the vital role of the porous HB structure on strain‐relaxation behavior is confirmed. Then, N‐doped‐C coated mesoporous α‐Fe₂O₃ HBs are designed and synthesized using a multistep soft/hard‐templating strategy. The material has several advantages: (i) there is space to accommodate strains without sacrificing volumetric energy density, unlike with hollow spheres; (ii) the mesoporous hollow structure shortens ion diffusion lengths and allows for high‐rate induced lithiation reactivation; and (iii) the N‐doped carbon nanolayer can enhance conductivity. As an anode in lithium‐ion batteries, the material exhibits a very high reversible capacity of 1452 mAh g^?1 at 0.1 A g^?1, excellent cycling stability of 1600 cycles (964 mAh g^?1 at 2 A g^?1), and outstanding rate performance (609 mAh g^?1 at 8 A g^?1). Notably, the volumetric specific capacity of composite electrode is 42% greater than that of hollow spheres. When used in potassium‐ion batteries, the material also shows high capacity and cycle stability.     

Watermelon‐Like Structured SiOx–TiO2@C Nanocomposite as a High‐Performance Lithium‐Ion Battery Anode

A unique watermelon‐like structured SiO_x–TiO₂@C nanocomposite is synthesized by a scalable sol–gel method combined with carbon coating process. Ultrafine TiO₂ nanocrystals are uniformly embedded inside SiO_x particles, forming SiO_x–TiO₂ dual‐phase cores, which are coated with outer carbon shells. The incorporation of TiO₂ component can effectively enhance the electronic and lithium ionic conductivities inside the SiO_x particles, release the structure stress caused by alloying/dealloying of Si component and maximize the capacity utilization by modifying the Si–O bond feature and decreasing the O/Si ratio (x‐value). The synergetic combination of these advantages enables the synthesized SiO_x–TiO₂@C nanocomposite to have excellent electrochemical performances, including high specific capacity, excellent rate capability, and stable long‐term cycleability. A stable specific capacity of ≈910 mAh g^?1 is achieved after 200 cycles at the current density of 0.1 A g^?1 and ≈700 mAh g^?1 at 1 A g^?1 for over 600 cycles. These results suggest a great promise of the proposed particle architecture, which may have potential applications in the improvement of various energy storage materials.     

Ti3+ Self‐Doped Dark Rutile TiO2 Ultrafine Nanorods with Durable High‐Rate Capability for Lithium‐Ion Batteries

Dark‐colored rutile TiO₂ nanorods doped by electroconducting Ti³⁺ have been obtained uniformly with an average diameter of ≈7 nm, and have been first utilized as anodes in lithium‐ion batteries. They deliver a high reversible specific capacity of 185.7 mAh g^?1 at 0.2 C (33.6 mA g^?1) and maintain 92.1 mAh g^?1 after 1000 cycles at an extremely high rate 50 C with an outstanding retention of 98.4%. Notably, the coulombic efficiency of Ti³⁺–TiO₂ has been improved by approximately 10% compared with that of pristine rutile TiO₂, which can be mainly attributed to its prompt electron transfer because of the introduction of Ti³⁺. Again the synergetic merits are noticed when the promoted electronic conductivity is combined with a shortened Li⁺ diffusion length resulting from the ultrafine nanorod structure, giving rise to the remarkable rate capabilities and extraordinary cycling stabilities for applications in fast and durable charge/discharge batteries. It is of great significance to incorporate Ti³⁺ into rutile TiO₂ to exhibit particular electrochemical characteristics triggering an effective way to improve the energy storage properties.     

Battery Performance and Photocatalytic Activity of Mesoporous Anatase TiO2 Nanospheres/Graphene Composites by Template‐Free Self‐Assembly

Nanosized mesoporous anatase TiO₂ particles have important applications in high‐performance lithium ion batteries and efficient photocatalysis. In contrast to the conventional synthesis routes where various soft or hard templates are usually employed, the direct growth of uniform mesoporous anatase TiO₂ nanospheres on graphene sheets by a template‐free self‐assembly process is presented. Compared to the conventional mesoporous anatase particles consisting of polycrystalline TiO₂, the microstructure of obtained mesoporous anatase nanospheres on graphene sheets is single‐crystal‐like. The growth mechanism, lithium ion battery performance, and photocatalytic activity of the resultant mesoporous anatase TiO₂ nanospheres/graphene composites are thoroughly investigated. In comparison to the reference TiO₂, the composite shows substantial improvement in lithium specific capacity from 1 C to 50 C, and photocatalytic removing organic pollutant and hydrogen evolution. More strikingly, the specific capacity of the composite at the rate of 50 C is as high as 97 mA h g^?1, 6 times higher than that of the reference TiO₂.     

Edge‐Enriched Ultrathin MoS2 Embedded Yolk‐Shell TiO2 with Boosted Charge Transfer for Superior Photocatalytic H2 Evolution

Exploring TiO₂‐photocatalysts for sunlight conversion has high demand in artificial photosynthesis. In this work, edge‐enriched ultrathin molybdenum disulfide (MoS₂) flakes are uniformly embedded into the bulk of yolk‐shell TiO₂ as a cocatalyst to accelerate photogenerated‐electron transfer from the bulk to the surface of TiO₂. The as‐formed MoS₂/TiO₂ (0.14 wt%) hybrids exhibit a high hydrogen evolution rate (HER) of 2443 µmol g^?1 h^?1, about 1000% and 470% of that of pristine TiO₂ (247 µmol g^?1 h^?1) and bulk MoS₂ decorated TiO₂ (513 µmol g^?1 h^?1). Such a greatly enhanced HER is attributed to the exposed catalytic edges of the ultrathin MoS₂ flakes with a robust chemical linkage (Ti? S bond), providing rapid charge transfer channels between TiO₂ and MoS₂. The catalytic stability is promoted by the antiaggregation of the highly dispersed MoS₂ flakes in the bulk of yolk‐shell TiO₂. The exponential fitted decay kinetics of time‐resolved photoluminescence (ns‐PL) spectra illustrates that embedding ultrathin MoS₂ flakes in TiO₂ effectively decreases the average lifetime of PL in the MoS₂/TiO₂ hybrids (τ_ave = 4.55 ns), faster than that of pristine TiO₂ (≈7.17 ns) and the bulk MoS₂/TiO₂ (≈6.13 ns), allowing a superior charge separation and charge trapping process for reducing water.     

Oxygen Vacancies Evoked Blue TiO2(B) Nanobelts with Efficiency Enhancement in Sodium Storage Behaviors

Oxygen vacancies (OVs) dominate the physical and chemical properties of metal oxides, which play crucial roles in the various fields of applications. Density functional theory calculations show the introduction of OVs in TiO₂(B) gives rise to better electrical conductivity and lower energy barrier of sodiation. Here, OVs evoked blue TiO₂(B) (termed as B‐TiO₂(B)) nanobelts are successfully designed upon the basis of electronically coupled conductive polymers to TiO₂, which is confirmed by electron paramagnetic resonance and X‐ray photoelectron spectroscopy. The superiorities of OVs with the aid of carbon encapsulation lead to higher capacity (210.5 mAh g^?1 (B‐TiO₂(B)) vs 102.7 mAh g^?1 (W‐TiO₂(B)) at 0.5 C) and remarkable long‐term cyclability (the retention of 94.4% at a high rate of 10 C after 5000 times). In situ X‐ray diffractometer analysis spectra also confirm that an enlarged interlayer spacing stimulated by OVs is beneficial to accommodate insertion and removal of sodium ions to accelerate storage kinetics and preserve its original crystal structure. The work highlights that injecting OVs into metal oxides along with carbon coating is an effective strategy for improving capacity and cyclability performances in other metal oxide based electrochemical energy systems.     

Reconstruction of Conformal Nanoscale MnO on Graphene as a High‐Capacity and Long‐Life Anode Material for Lithium Ion Batteries

To tackle the issue of inferior cycle stability and rate capability for MnO anode materials in lithium ion batteries, a facile strategy is explored to prepare a hybrid material consisting of MnO nanocrystals grown on conductive graphene nanosheets. The prepared MnO/graphene hybrid anode exhibits a reversible capacity as high as 2014.1 mAh g^?1 after 150 discharge/charge cycles at 200 mA g^?1, excellent rate capability (625.8 mAh g^?1 at 3000 mA g^?1), and superior cyclability (843.3 mAh g^?1 even after 400 discharge/charge cycles at 2000 mA g^?1 with only 0.01% capacity loss per cycle). The results suggest that the reconstruction of the MnO/graphene electrodes is intrinsic due to conversion reactions. A long‐term stable nanoarchitecture of graphene‐supported ultrafine manganese oxide nanoparticles is formed upon cycling, which yields a long‐life anode material for lithium ion batteries. The lithiation and delithiation behavior suggests that the further oxidation of Mn(II ) to Mn(IV ) and the interfacial lithium storage upon cycling contribute to the enhanced specific capacity. The excellent rate capability benefits from the presence of conductive graphene and a short transportation length for both lithium ions and electrons. Moreover, the as‐formed hybrid nanostructure of MnO on graphene may help achieve faster kinetics of conversion reactions.     

Bimetal–Organic Framework: One‐Step Homogenous Formation and its Derived Mesoporous Ternary Metal Oxide Nanorod for High‐Capacity,High‐Rate,and Long‐Cycle‐Life Lithium Storage

Metal–organic frameworks (MOFs) and relative structures with uniform micro/mesoporous structures have shown important applications in various fields. This paper reports the synthesis of unprecedented mesoporous Ni_xCo_3?xO₄ nanorods with tuned composition from the Co/Ni bimetallic MOF precursor. The Co/Ni‐MOFs are prepared by a one‐step facile microwave‐assisted solvothermal method rather than surface metallic cation exchange on the preformed one‐metal MOF template, therefore displaying very uniform distribution of two species and high structural integrity. The obtained mesoporous Ni_0.3Co_2.7O₄ nanorod delivers a larger‐than‐theoretical reversible capacity of 1410 mAh g^?1 after 200 repetitive cycles at a small current of 100 mA g^?1 with an excellent high‐rate capability for lithium‐ion batteries. Large reversible capacities of 812 and 656 mAh g^?1 can also be retained after 500 cycles at large currents of 2 and 5 A g^?1, respectively. These outstanding electrochemical performances of the ternary metal oxide have been mainly attributed to its interconnected nanoparticle‐integrated mesoporous nanorod structure and the synergistic effect of two active metal oxide components.     

A New Strategy to Build a High‐Performance P′2‐Type Cathode Material through Titanium Doping for Sodium‐Ion Batteries

Herein, Ti⁴⁺ in P′2‐Na_0.67[(Mn_0.78Fe_0.22)_0.9Ti_0.1]O₂ is proposed as a new strategy for optimization of Mn‐based cathode materials for sodium‐ion batteries, which enables a single phase reaction during de‐/sodiation. The approach is to utilize the stronger Ti–O bond in the transition metal layers that can suppress the movements of Mn–O and Fe–O by sharing the oxygen with Ti by the sequence of Mn–O–Ti–O–Fe. It delivers a discharge capacity of ≈180 mAh g^?1 over 200 cycles (86% retention), with S‐shaped smooth charge–discharge curves associated with a small volume change during cycling. The single phase reaction with a small volume change is further confirmed by operando synchrotron X‐ray diffraction. The low activation barrier energy of ≈541 meV for Na⁺ diffusion is predicted using first‐principles calculations. As a result, Na_0.67[(Mn_0.78Fe_0.22)_0.9Ti_0.1]O₂ can deliver a high reversible capacity of ≈153 mAh g^?1 even at 5C (1.3 A g^?1), which corresponds to ≈85% of the capacity at 0.1C (26 mA g^?1). The nature of the sodium storage mechanism governing the ultrahigh electrode performance in a full cell with a hard carbon anode is elucidated, revealing the excellent cyclability and good retention (≈80%) for 500 cycles (111 mAh g^?1) at 5C (1.3 A g^?1).     

A Green and Facile Way to Prepare Granadilla‐Like Silicon‐Based Anode Materials for Li‐Ion Batteries

A yolk‐shell‐structured carbon@void@silicon (CVS) anode material in which a void space is created between the inside silicon nanoparticle and the outer carbon shell is considered as a promising candidate for Li‐ion cells. Untill now, all the previous yolk‐shell composites were fabricated through a templating method, wherein the SiO₂ layer acts as a sacrificial layer and creates a void by a selective etching method using toxic hydrofluoric acid. However, this method is complex and toxic. Here, a green and facile synthesis of granadilla‐like outer carbon coating encapsulated silicon/carbon microspheres which are composed of interconnected carbon framework supported CVS nanobeads is reported. The silicon granadillas are prepared via a modified templating method in which calcium carbonate was selected as a sacrificial layer and acetylene as a carbon precursor. Therefore, the void space inside and among these CVS nanobeads can be formed by removing CaCO₃ with diluted hydrochloric acid. As prepared, silicon granadillas having 30% silicon content deliver a reversible capacity of around 1100 mAh g^?1 at a current density of 250 mA g^?1 after 200 cycles. Besides, this composite exhibits an excellent rate performance of about 830 and 700 mAh g^?1 at the current densities of 1000 and 2000 mA g^?1, respectively.     

Freestanding Metallic 1T MoS2 with Dual Ion Diffusion Paths as High Rate Anode for Sodium‐Ion Batteries

This work studies for the first time the metallic 1T MoS₂ sandwich grown on graphene tube as a freestanding intercalation anode for promising sodium‐ion batteries (SIBs). Sodium is earth‐abundant and readily accessible. Compared to lithium, the main challenge of sodium‐ion batteries is its sluggish ion diffusion kinetic. The freestanding, porous, hollow structure of the electrode allows maximum electrolyte accessibility to benefit the transportation of Na⁺ ions. Meanwhile, the metallic MoS₂ provides excellent electron conductivity. The obtained 1T MoS₂ electrode exhibits excellent electrochemical performance: a high reversible capacity of 313 mAh g^?1 at a current density of 0.05 A g^?1 after 200 cycles and a high rate capability of 175 mAh g^?1 at 2 A g^?1. The underlying mechanism of high rate performance of 1T MoS₂ for SIBs is the high electrical conductivity and excellent ion accessibility. This study sheds light on using the 1T MoS₂ as a novel anode for SIBs.     

Highly Connected Silicon–Copper Alloy Mixture Nanotubes as High‐Rate and Durable Anode Materials for Lithium‐Ion Batteries

Seeking high‐capacity, high‐rate, and durable anode materials for lithium‐ion batteries (LIBs) has been a crucial aspect to promote the use of electric vehicles and other portable electronics. Here, a novel alloy‐forming approach to convert amorphous Si (a‐Si)‐coated copper oxide (CuO) core–shell nanowires (NWs) into hollow and highly interconnected Si–Cu alloy (mixture) nanotubes is reported. Upon a simple H₂ annealing, the CuO cores are reduced and diffused out to alloy with the a‐Si shell, producing highly interconnected hollow Si–Cu alloy nanotubes, which can serve as high‐capacity and self‐conductive anode structures with robust mechanical support. A high specific capacity of 1010 mAh g^?1 (or 780 mAh g^?1) has been achieved after 1000 cycles at 3.4 A g^?1 (or 20 A g^?1), with a capacity retention rate of ≈84% (≈88%), without the use of any binder or conductive agent. Remarkably, they can survive an extremely fast charging rate at 70 A g^?1 for 35 runs (corresponding to one full cycle in 30 s) and recover 88% capacity. This novel alloy‐nanotube structure could represent an ideal candidate to fulfill the true potential of Si‐loaded LIB applications.     

Enhanced Ionic/Electronic Transport in Nano‐TiO2/Sheared CNT Composite Electrode for Na+ Insertion‐based Hybrid Ion‐Capacitors

Ion‐insertion capacitors show promise to bridge the gap between supercapacitors of high power densities and batteries of high energy densities. While research efforts have primarily focused on Li⁺‐based capacitors (LICs), Na⁺‐based capacitors (SICs) are theoretically cheaper and more sustainable. Owing to the larger size of Na⁺ compared to Li⁺, finding high‐rate anode materials for SICs has been challenging. Herein, an SIC anode architecture is reported consisting of TiO₂ nanoparticles anchored on a sheared‐carbon nanotubes backbone (TiO₂/SCNT). The SCNT architecture provides advantages over other carbon architectures commonly used, such as reduced graphene oxide and CNT. In a half‐cell, the TiO₂/SCNT electrode shows a capacity of 267 mAh g^?1 at a 1 C charge/discharge rate and a capacity of 136 mAh g^?1 at 10 C while maintaining 87% of initial capacity over 1000 cycles. When combined with activated carbon (AC) in a full cell, an energy density and power density of 54.9 Wh kg^?1 and 1410 W kg^?1, respectively, are achieved while retaining a 90% capacity retention over 5000 cycles. The favorable rate capability, energy and power density, and durability of the electrode is attributed to the enhanced electronic and Na⁺ conductivity of the TiO₂/SCNT architecture.     

A Na3V2(PO4)2O1.6F1.4 Cathode of Zn‐Ion Battery Enabled by a Water‐in‐Bisalt Electrolyte

Aqueous zinc‐ion batteries are receiving increasing attention; however, the development of high‐voltage cathodes is limited by the narrow voltage window of conventional aqueous electrolytes. Herein, it is reported that Na₃V₂(PO₄)₂O_1.6F_1.4 exhibits the excellent performance, optimal to date, among polyanion cathode materials in a novel neutral water‐in‐bisalts electrolyte of 25 m ZnCl₂ + 5 m NH₄Cl. It delivers a reversible capacity of 155 mAh g^?1 at 50 mA g^?1, a high average operating potential of ≈1.46 V, and stable cyclability of 7000 cycles at 2 A g^?1.     

Large‐scale Synthesis of Urchin‐like Mesoporous TiO2 Hollow Spheres by Targeted Etching and Their Photoelectrochemical Properties

A versatile targeted etching strategy is developed for the large‐scale synthesis of urchin‐like mesoporous TiO₂ hollow spheres (UMTHS) with tunable particle size. Its key feature is the use of a low‐temperature hydrothermal reaction of surface‐fluorinated, amorphous, hydrous TiO₂ solid spheres (AHTSS) under the protection of a polyvinylpyrrolidone (PVP) coating. With the confinement of PVP and water penetration, the highly porous AHTSS are selectively etched and hollowed by fluoride without destroying their spherical morphology. Meanwhile TiO₂ hydrates are gradually crystallized and their growth is preferentially along anatase (101) planes, reconstructing an urchin‐like shell consisting of numerous radially arranged single‐crystal anatase nanothorns. Complex hollow structures, such as core–shell and yolk–shell structures, can also be easily synthesized via additional protection of the interior by pre‐filling AHTSS with polyethylene glycol (PEG). The hollowing transformation is elucidated by the synergetic effect of etching, PVP coating, low hydrothermal reaction temperature, and the unique microstructure of AHTSS. The synthesized UMTHS with a large surface area of up to 128.6 m² g^‐1 show excellent light‐harvesting properties and present superior performances in photocatalytic removal of gaseous nitric oxide (NO) and photoelectrochemical solar energy conversion as photoanodes for dye‐sensitized mesoscopic solar cells.     

A High‐Energy Li‐Ion Battery Using a Silicon‐Based Anode and a Nano‐Structured Layered Composite Cathode

High capacity electrodes based on a Si composite anode and a layered composite oxide cathode, Ni‐rich Li[Ni_0.75Co_0.1Mn_0.15]O₂, are evaluated and combined to fabricate a high energy lithium ion battery. The Si composite anode, Si/C‐IWGS (internally wired with graphene sheets), is prepared by a scalable sol–gel process. The Si/C‐IWGS anode delivers a high capacity of >800 mAh g^?1 with an excellent cycling stability of up to 200 cycles, mainly due to the small amount of graphene (～6 wt%). The cathode (Li[Ni_0.75Co_0.1Mn_0.15]O₂) is structurally optimized (Ni‐rich core and a Ni‐depleted shell with a continuous concentration gradient between the core and shell, i.e., a full concentration gradient, FCG, cathode) so as to deliver a high capacity (>200 mAh g^?1) with excellent stability at high voltage (～4.3 V). A novel lithium ion battery system based on the Si/C‐IWGS anode and FCG cathode successfully demonstrates a high energy density (240 Wh kg^?1 at least) as well as an unprecedented excellent cycling stability of up to 750 cycles between 2.7 and 4.2 V at 1C. As a result, the novel battery system is an attractive candidate for energy storage applications demanding a high energy density and long cycle life.     

Efficient Ni2Co4P3 Nanowires Catalysts Enhance Ultrahigh‐Loading Lithium–Sulfur Conversion in a Microreactor‐Like Battery

High‐loading lithium–sulfur (Li–S) batteries suffer from poor electrochemical properties. Electrocatalysts can accelerate polysulfides conversion and suppress their migration to improve battery cyclability. However, catalysts for Li–S batteries usually lack a rational design. A d‐band tuning strategy is reported by alloying cobalt to metal sites of Ni₂P to enhance the interaction between polysulfides and catalysts. A molecular or atomic level analysis reveals that Ni₂Co₄P₃ is able to weaken the S? S bonds and lower the activation energy of polysulfides conversion, which is confirmed with temperature‐dependent experiments. Ni₂Co₄P₃ nanowires are further fabricated on a porous nickel scaffold to unfold the catalytic activity by its large surface area. Using a simple ion‐selective filtration shell, a microreactor‐like S cathode (MLSC) is constructed to realize ultrahigh S loading (25 mg cm^?2). As such, a microreactor design integrates reaction and separation in one cell and can effectively address the polysulfide issues, the MLSC cell demonstrates excellent properties of cyclability and high capacity (1223 mAh g^?1 at 0.1 C). More importantly, the catalyst's designs and microreactor strategies provide new approaches for addressing the complicated issues of Li–S batteries.     

Combined High Catalytic Activity and Efficient Polar Tubular Nanostructure in Urchin‐Like Metallic NiCo2Se4 for High‐Performance Lithium–Sulfur Batteries

Urchin‐shaped NiCo₂Se₄ (u‐NCSe) nanostructures as efficient sulfur hosts are synthesized to overcome the limitations of lithium–sulfur batteries (LSBs). u‐NCSe provides a beneficial hollow structure to relieve volumetric expansion, a superior electrical conductivity to improve electron transfer, a high polarity to promote absorption of lithium polysulfides (LiPS), and outstanding electrocatalytic activity to accelerate LiPS conversion kinetics. Owing to these excellent qualities as cathode for LSBs, S@u‐NCSe delivers outstanding initial capacities up to 1403 mAh g^?1 at 0.1 C and retains 626 mAh g^?1 at 5 C with exceptional rate performance. More significantly, a very low capacity decay rate of only 0.016% per cycle is obtained after 2000 cycles at 3 C. Even at high sulfur loading (3.2 mg cm^?2), a reversible capacity of 557 mAh g^?1 is delivered after 600 cycles at 1 C. Density functional theory calculations further confirm the strong interaction between NCSe and LiPS, and cytotoxicity measurements prove the biocompatibility of NCSe. This work not only demonstrates that transition metal selenides can be promising candidates as sulfur host materials, but also provides a strategy for the rational design and the development of LSBs with long‐life and high‐rate electrochemical performance.     

Inserting Sn Nanoparticles into the Pores of TiO2−x–C Nanofibers by Lithiation

Tin holds promise as an anode material for lithium‐ion batteries (LIBs) because of its high theoretical capacity, but its cycle life is limited by structural degradation. Herein, a novel approach is exploited to insert Sn nanoparticles into the pores of highly stable titanium dioxide–carbon (TiO_2?x–C) nanofiber substrates that can effectively localize the postformed smaller Sn nanoparticles, thereby address the problem of structural degradation, and thus achieve improved anode performance. During first lithiation, a Li_4.4Sn alloy is inserted into the pores surrounding the initial Sn nanoparticles in TiO_2?x–C nanofibers by its large volume expansion. Thereafter, the original Sn nanoparticle with a diameter of about 150 nm cannot be recovered by the delithiation because of the surface absorption between inserted Sn nanoparticles and the TiO_2?x–C substrate, resulting in many smaller Sn nanoparticles remaining in the pores. Batteries containing these porous TiO_2?x–C–Sn nanofibers exhibit a high capacity of 957 mAh g^?1 after 200 cycles at 0.1 A g^?1 and can cycle over 10 000 times at 3 A g^?1 while retaining 82.3% of their capacity, which represents the longest cycling life of Sn‐based anodes for LIBs so far. This interesting method can provide new avenues for other high‐capacity anode material systems that suffer from significant volume expansion.