Binary Li4Ti5O12‐Li2Ti3O7 Nanocomposite as an Anode Material for Li‐Ion Batteries

Li₄Ti₅O₁₂ typically shows a flat charge/discharge curve, which usually leads to difficulty in the voltage‐based state of charge (SOC) estimation. In this study, a facile quench‐assisted solid‐state method is used to prepare a highly crystalline binary Li₄Ti₅O₁₂‐Li₂Ti₃O₇ nanocomposite. While Li₄Ti₅O₁₂ exhibits a sudden voltage rise/drop near the end of its charge/discharge curve, this binary nanocomposite has a tunable sloped voltage profile. The nanocomposite exhibits a unique lamellar morphology consisting of interconnected nanograins of ≈20 nm size with a hierarchical nanoporous structure, contributing to an enhanced rate capability with a capacity of 128 mA h g^?1 at a high C‐rate of 10 C, and excellent cycling stability.     

Fe3O4 Nanoparticles Confined in Mesocellular Carbon Foam for High Performance Anode Materials for Lithium‐Ion Batteries

Fe₃O₄ nanocrystals confined in mesocellular carbon foam (MSU‐F‐C) are synthesized by a “ host–guest ” approach and tested as an anode material for lithium‐ion batteries (LIBs). Briefly, an iron oxide precursor, Fe(NO₃)₃·9H₂O, is impregnated in MSU‐F‐C having uniform cellular pores ～30 nm in dia­meter, followed by heat‐treatment at 400 °C for 4 h under Ar. Magnetite Fe₃O₄ nanocrystals with sizes between 13–27 nm are then successfully fabricated inside the pores of the MSU‐F‐C, as confirmed by transmission electron microscopy (TEM), dark‐field scanning transmission electron microscopy (STEM), energy dispersive X‐ray spectroscopy (EDS), X‐ray diffraction (XRD), and nitrogen sorption isotherms. The presence of the carbon most likely allows for reduction of some of the Fe³⁺ ions to Fe²⁺ ions via a carbothermoreduction process. A Fe₃O₄/MSU‐F‐C nanocomposite with 45 wt% Fe₃O₄ exhibited a first charge capacity of 1007 mA h g^?1 (Li⁺ extraction) at 0.1 A g^?1 (～0.1 C rate) with 111% capacity retention at the 150^th cycle, and retained 37% capacity at 7 A g^?1 (～7 C rate). Because the three dimensionally interconnected open pores are larger than the average nanosized Fe₃O₄ particles, the large volume expansion of Fe₃O₄ upon Li‐insertion is easily accommodated inside the pores, resulting in excellent electrochemical performance as a LIB anode. Furthermore, when an ultrathin Al₂O₃ layer (<4 Å) was deposited on the composite anode using atomic layer deposition (ALD), the durability, rate capability and undesirable side reactions are significantly improved.     

Highly Improved Rate Capability for a Lithium‐Ion Battery Nano‐Li4Ti5O12 Negative Electrode via Carbon‐Coated Mesoporous Uniform Pores with a Simple Self‐Assembly Method

A mesostructured spinel Li₄Ti₅O₁₂ (LTO)‐carbon nanocomposite (denoted as Meso‐LTO‐C) with large (>15 nm) and uniform pores is simply synthesized via block copolymer self‐assembly. Exceptionally high rate capability is then demonstrated for Li‐ion battery (LIB) negative electrodes. Polyisoprene‐block‐poly(ethylene oxide) (PI‐b‐PEO) with a sp²‐hybridized carbon‐containing hydrophobic block is employed as a structure‐directing agent. Then the assembled composite material is crystallized at 700 °C enabling conversion to the spinel LTO structure without loss of structural integrity. Part of the PI is converted to a conductive carbon that coats the pores of the Meso‐LTO‐C. The in situ pyrolyzed carbon not only maintains the porous mesostructure as the LTO is crystallized, but also improves the electronic conductivity. A Meso‐LTO‐C/Li cell then cycles stably at 10 C‐rate, corresponding to only 6 min for complete charge and discharge, with a reversible capacity of 115 mA h g^?1 with 90% capacity retention after 500 cycles. In sharp contrast, a Bulk‐LTO/Li cell exhibits only 69 mA h g^?1 at 10 C‐rate. Electrochemical impedance spectroscopy (EIS) with symmetric LTO/LTO cells prepared from Bulk‐LTO and Meso‐LTO‐C cycled in different potential ranges reveals the factors contributing to the vast difference between the rate‐capabilities. The carbon‐coated mesoporous structure enables highly improved electronic conductivity and significantly reduced charge transfer resistance, and a much smaller overall resistance is observed compared to Bulk‐LTO. Also, the solid electrolyte interphase (SEI)‐free surface due to the limited voltage window (>1 V versus Li/Li⁺) contributes to dramatically reduced resistance.     

A High‐Performance Li–B–H Electrolyte for All‐Solid‐State Li Batteries

Highly Li‐ion conductive Li₄(BH₄)₃I@SBA‐15 is synthesized by confining the LiI doped LiBH₄ into mesoporous silica SBA‐15. Uniform nanoconfinement of P6₃ mc phase Li₄(BH₄)₃I in SBA‐15 mesopores leads to a significantly enhanced conductivity of 2.5 × 10^?4 S cm^?1 with a Li‐ion transference number of 0.97 at 35 °C. The super Li‐ion mobility in the interface layer with a thickness of 1.2 nm between Li₄(BH₄)₃I and SBA‐15 is believed to be responsible for the fast Li‐ion conduction in Li₄(BH₄)₃I@SBA‐15. Additionally, Li₄(BH₄)₃I@SBA‐15 also exhibits a wide apparent electrochemical stability window (0 to 5 V vs Li/Li⁺) and a superior Li dendrite suppression capability (critical current density 2.6 mA cm^?2 at 55 °C) due to the formation of stable interphases. More importantly, Li₄(BH₄)₃I@SBA‐15‐based Li batteries using either high‐capacity sulfur cathode or high‐voltage oxide cathode show excellent electrochemical performances, making Li₄(BH₄)₃I@SBA‐15 a very attractive electrolyte for next‐generation all‐solid‐state Li batteries.     

High‐Performance Carbon‐LiMnPO4 Nanocomposite Cathode for Lithium Batteries

A cathode material of an electrically conducting carbon‐LiMnPO₄ nanocomposite is synthesized by ultrasonic spray pyrolysis followed by ball milling. The effect of the carbon content on the physicochemical and electrochemical properties of this material is extensively studied. A LiMnPO₄ electrode with 30 wt% acetylene black (AB) carbon exhibits an excellent rate capability and good cycle life in cell tests at 55 and 25 °C. This electrode delivers a discharge capacity of 158 mAh g^?1 at 1/20 C, 126 mAh g^?1 at 1 C, and 107 mAh g^?1 at 2 C rate, which are the highest capacities reported so far for this type of electrode. Transmission electron microscopy and Mn dissolution results confirm that the carbon particles surrounding the LiMnPO₄ protect the electrode from HF attack, and thus lead to a reduction of the Mn dissolution that usually occurs with this electrode. The improved electrochemical properties of the C‐LiMnPO₄ electrode are also verified by electrochemical impedance spectroscopy.     

Nanophase ZnCo2O4 as a High Performance Anode Material for Li‐Ion Batteries

ZnCo₂O₄ has been synthesized by the low‐temperature and cost‐effective urea combustion method. X‐ray diffraction (XRD), HR‐TEM and selected area electron diffraction (SAED) studies confirmed its formation in pure and nano‐phase form with particle size ～ 15–20 nm. Galvanostatic cycling of nano‐ZnCo₂O₄ in the voltage range 0.005–3.0 V versus Li at 60 mA g^–1 gave reversible capacities of 900 and 960 mA h g^–1, when cycled at 25 °C and 55 °C, respectively. These values correspond to ～ 8.3 and ～ 8.8 mol of recyclable Li per mole of ZnCo₂O₄. Almost stable cycling performance was exhibited in the range 5–60 cycles at 60 mA g^–1 and at 25 °C with ～ 98 % coulombic efficiency. A similar cycling stability at 55 °C, and good rate‐capability both at 25 and 55 °C were found. The average discharge‐ and charge‐potentials were ～ 1.2 V and ～ 1.9 V, respectively. The ex‐situ‐XRD, ‐HRTEM, ‐SAED and galvanostatic cycling data are consistent with a reaction mechanism for Li‐recyclability involving both de‐alloying‐alloying of Zn and displacement reactions, viz., LiZn ? Zn ? ZnO and Co ? CoO ? Co₃O₄. For the first time we have shown that both Zn‐ and Co‐ions act as mutual beneficial matrices and reversible capacity contribution of Zn through both alloy formation and displacement reaction takes place to yield stable and high capacities. Thus, nano‐ZnCo₂O₄ ranks among the best oxide materials with regard to Li‐recyclability.     

2D Nanospace Confined Synthesis of Pseudocapacitance‐Dominated MoS2‐in‐Ti3C2 Superstructure for Ultrafast and Stable Li/Na‐Ion Batteries

Exploring a universal strategy to implement the precise control of 2D nanomaterials in size and layer number is a big challenge for achieving ultrafast and stable Li/Na‐ion batteries. Herein, the confined synthesis of 1–3 layered MoS₂ nanocrystals into 2D Ti₃C₂ interlayer nanospace with the help of electrostatic attraction and subsequent cetyltrimethyl ammonium bromide (CTAB) directed growth is reported. The MoS₂ nanocrystals are tightly anchored into the interlayer by 2D confinement effect and strong Mo? C covalent bond. Impressively, the disappearance of Li⁺ intercalated into MoS₂ reduction peak is successfully observed for the first time in the experiment, showing in a typical surface‐controlled charge storage behavior. The pseudocapacitance‐dominated contribution guarantees a much faster and more stable Li/Na storage performance. As predicted, this electrode exhibits a very high Li⁺ storage capacity of 340 mAh g^?1 even at 20 A g^?1 and a long cycle life (>1000 times). It also shows an excellent Na⁺ storage capacity of 310 mAh g^?1 at 1 A g^?1 with a 1600 times high‐rate cycling. Such impressive confined synthesis strategy can be extended to the precise control of other 2D nanomaterials.     

Intercalated Electrolyte with High Transference Number for Dendrite‐Free Solid‐State Lithium Batteries

Solid‐state lithium (Li) batteries using solid electrolytes and Li anodes are highly desirable because of their high energy densities and intrinsic safety. However, low ambient‐temperature conductivity and poor interface compatibility of solid electrolytes as well as Li dendrite formation cause large polarization and poor cycling stability. Herein, a high transference number intercalated composite solid electrolyte (CSE) is prepared by the combination of a solution‐casting and hot‐pressing method using layered lithium montmorillonite, poly(ethylene carbonate), lithium bis(fluorosulfonyl)imide, high‐voltage fluoroethylene carbonate additive, and poly(tetrafluoroethylene) binder. The electrolyte presents high ionic conductivity (3.5 × 10^?4 S cm^?1), a wide electrochemical window (4.6 V vs Li⁺/Li), and high ionic transference number (0.83) at 25 °C. In addition, a 3D Li anode is also fabricated via a facile thermal infusion strategy. The synergistic effect of high transference number intercalated electrolyte and 3D Li anode is more favorable to suppress Li dendrites in a working battery. The solid‐state batteries based on LiFePO₄ (Al₂O₃ @ LiNi_0.5Co_0.2Mn_0.3O₂), CSE, and 3D Li deliver admirable cycling stability with discharge capacity 145.9 mAh g^?1 (150.7 mAh g^?1) and capacity retention 91.9% after 200 cycles at 0.5 C (92.0% after 100 cycles at 0.2 C) at 25 °C. This work affords a splendid strategy for high‐performance solid‐state battery.     

Pseudocapacitive Trimetal Fe0.8CoMnO4 Nanoparticles@Carbon Nanofibers as High‐Performance Sodium Storage Anode with Self‐Supported Mechanism

Trimetal Fe_0.8CoMnO₄ (FCMO) nanocrystals with a diameter of about 50 nm perfectly embedded in N doped‐carbon composite nanofibers (denoted as FCMO@C) are successfully prepared through integrating double‐nozzle electrospinning with a drying and calcination process. The as‐prepared FCMO@C nanofibers maintain a high reversible capacity of 420 mAh g^?1 and about 90% capacity retention after 200 cycles at 0.1 A g^?1. For a long‐term cycle, the FCMO@C electrode exhibits excellent cycling stability (87% high capacity retention at 1 A g^?1 after 950 cycles). Kinetic analysis demonstrates that the electrochemical characteristics of the FCMO@C corresponds to the pseudocapacitive approach in charge storage as an anode for sodium ion batteries, which dominantly attributes the credit to FCMO nanocrystals to shorten the migration distance of Na⁺ ions and the nitrogen‐doped carbon skeleton to enhance the electronic transmission and favorably depress the volume expansion during the repeated insertion/extraction of Na⁺ ions. More significantly, a self‐supported mechanism via continuous electrochemical redox reaction of Fe, Co, and Mn can effectively relieve the volume change during charge and discharge. Therefore, this work can provide a new avenue to improve the sodium storage performance of the oxide anode materials.     

Self‐Standing Porous LiCoO2 Nanosheet Arrays as 3D Cathodes for Flexible Li‐Ion Batteries

Self‐standing electrodes are the key to realize flexible Li‐ion batteries. However, fabrication of self‐standing cathodes is still a major challenge. In this work, porous LiCoO₂ nanosheet arrays are grown on Au‐coated stainless steel (Au/SS) substrates via a facile “hydrothermal lithiation” method using Co₃O₄ nanosheet arrays as the template followed by quick annealing in air. The binder‐free and self‐standing LiCoO₂ nanosheet arrays represent the 3D cathode and exhibit superior rate capability and cycling stability. In specific, the LiCoO₂ nanosheet array electrode can deliver a high reversible capacity of 104.6 mA h g^?1 at 10 C rate and achieve a capacity retention of 81.8% at 0.1 C rate after 1000 cycles. By coupling with Li₄Ti₅O₁₂ nanosheet arrays as anode, an all‐nanosheet array based LiCoO₂//Li₄Ti₅O₁₂ flexible Li‐ion battery is constructed. Benefiting from the 3D nanoarchitectures for both cathode and anode, the flexible LiCoO₂//Li₄Ti₅O₁₂ battery can deliver large specific reversible capacities of 130.7 mA h g^?1 at 0.1 C rate and 85.3 mA h g^?1 at 10 C rate (based on the weight of cathode material). The full cell device also exhibits good cycling stability with 80.5% capacity retention after 1000 cycles at 0.1 C rate, making it promising for the application in flexible Li‐ion batteries.     

Fluorinated Polyimide as a Novel High‐Voltage Binder for High‐Capacity Cathode of Lithium‐Ion Batteries

An increase in the energy density of lithium‐ion batteries has long been a competitive advantage for advanced wireless devices and long‐driving electric vehicles. Li‐rich layered oxide, xLi₂MnO₃?(1?x)LiMn_1?y?zNi_yCo_zO₂, is a promising high‐capacity cathode material for high‐energy batteries, whose capacity increases by increasing charge voltage to above 4.6 V versus Li. Li‐rich layered oxide cathode however suffers from a rapid capacity fade during the high‐voltage cycling because of instable cathode–electrolyte interface, and the occurrence of metal dissolution, particle cracking, and structural degradation, particularly, at elevated temperatures. Herein, this study reports the development of fluorinated polyimide as a novel high‐voltage binder, which mitigates the cathode degradation problems through superior binding ability to conventional polyvinylidenefluoride binder and the formation of robust surface structure at the cathode. A full‐cell consisting of fluorinated polyimide binder‐assisted Li‐rich layered oxide cathode and conventional electrolyte without any electrolyte additive exhibits significantly improved capacity retention to 89% at the 100th cycle and discharge capacity to 223–198 mA h g^?1 even under the harsh condition of 55 °C and high charge voltage of 4.7 V, in contrast to a rapid performance fade of the cathode coated with polyvinylidenefluoride binder.     

Self‐Assembly of Flexible Free‐Standing 3D Porous MoS2‐Reduced Graphene Oxide Structure for High‐Performance Lithium‐Ion Batteries

Flexible freestanding electrodes are highly desired to realize wearable/flexible batteries as required for the design and production of flexible electronic devices. Here, the excellent electrochemical performance and inherent flexibility of atomically thin 2D MoS₂ along with the self‐assembly properties of liquid crystalline graphene oxide (LCGO) dispersion are exploited to fabricate a porous anode for high‐performance lithium ion batteries. Flexible, free‐standing MoS₂–reduced graphene oxide (MG) film with a 3D porous structure is fabricated via a facile spontaneous self‐assembly process and subsequent freeze‐drying. This is the first report of a one‐pot self‐assembly, gelation, and subsequent reduction of MoS₂/LCGO composite to form a flexible, high performance electrode for charge storage. The gelation process occurs directly in the mixed dispersion of MoS₂ and LCGO nanosheets at a low temperature (70 °C) and normal atmosphere (1 atm). The MG film with 75 wt% of MoS₂ exhibits a high reversible capacity of 800 mAh g^?1 at a current density of 100 mA g^?1. It also demonstrates excellent rate capability, and excellent cycling stability with no capacity drop over 500 charge/discharge cycles at a current density of 400 mA g^?1.     

High‐Performance Solid Polymer Electrolytes Filled with Vertically Aligned 2D Materials

Solid state lithium metal batteries are the most promising next‐generation power sources owing to their high energy density and safety. Solid polymer electrolytes (SPE) have gained wide attention due to the excellent flexibility, manufacturability, lightweight, and low‐cost processing. However, fatal drawbacks of the SPE such as the insufficient ionic conductivity and Li⁺ transference number at room temperature restrict their practical application. Here vertically aligned 2D sheets are demonstrated as an advanced filler for SPE with enhanced ionic conductivity, Li⁺ transference number, mechanical modulus, and electrochemical stability, using vermiculite nanosheets as an example. The vertically aligned vermiculite sheets (VAVS), prepared by the temperature gradient freezing, provide aligned, continuous, run‐through polymer‐filler interfaces after infiltrating with polyethylene oxide (PEO)‐based SPE. As a result, ionic conductivity as high as 1.89 × 10^?4 S cm^?1 at 25 °C is achieved with Li⁺ transference number close to 0.5. Along with their enhanced mechanical strength, Li|Li symmetric cells using VAVS–CSPE are stable over 1300 h with a low overpotential. LiFePO₄ in all‐solid‐state lithium metal batteries with VAVS–CSPE could deliver a specific capacity of 167 mAh g^?1 at 0.1 C at 35 °C and 82% capacity retention after 200 cycles at 0.5 C.     

Synergistically Assembled Li2S/FWNTs@Reduced Graphene Oxide Nanobundle Forest for Free‐Standing High‐Performance Li2S Cathodes

Lithium sulfide (Li₂S) has attracted increasing attention as a promising cathode because of its compatibility with more practical lithium‐free anode materials and its high specific capacity. However, it is still a challenge to develop Li₂S cathodes with low electrochemical overpotential, high capacity and reversibility, and good rate performance. This work designs and fabricates a practical Li₂S cathode composed of Li₂S/few‐walled carbon nanotubes@reduced graphene oxide nanobundle forest (Li₂S/FWNTs@rGO NBF). Hierarchical nanostructures are obtained by annealing the Li₂SO₄/FWNTs@GO NBF, which is prepared by a facile and scalable solution‐based self‐assembly method. Systematic characterizations reveal that in this unique NBF nanostructure, FWNTs act as axial shafts to direct the structure, Li₂S serves as the internal active material, and GO sheets provide an external coating to minimize the direct contact of Li₂S with the electrolyte. When used as a cathode, the Li₂S/FWNTs@rGO NBF achieve a high capacity of 868 mAh g^?1_Li2S at 0.2C after 300 cycles and an outstanding rate performance of 433 mAh g^?1_Li2S even at 10C, suggesting that this Li₂S cathode is a promising candidate for ultrafast charge/discharge applications. The design and synthetic strategies outlined here can be readily applied to the processing of other novel functional materials to obtain a much wider range of applications.     

Highly Stable Cycling of Amorphous Li2CO3‐Coated α‐Fe2O3 Nanocrystallines Prepared via a New Mechanochemical Strategy for Li‐Ion Batteries

In this study, an amorphous Li₂CO₃‐coated nanocrystalline α‐Fe₂O₃ hierarchical structure is synthesized for the first time using a facile one‐step mechanochemical process at room temperature, taking advantage of the concurrence of repeated fracture‐cold welding of material's particles and a gas‐solid redox reaction. The conformal coating and hierarchical structure significantly increase the cycling durability and rate capability. Typically, a 1–3 nm thick amorphous Li₂CO₃ layer is conformally coated on Fe₂O₃ nanocrystallines (≈10 nm in size) that form hierarchically aggregated particles 400–800 nm in size by ball milling α‐Fe₂O₃ with LiH in CO₂. The prepared Li₂CO₃‐coated nanocrystalline α‐Fe₂O₃ exhibits highly stable long‐term cyclability as it delivers a reversible capacity of 975 mAh g^?1 with 99% of retention after 400 cycles at 100 mA g^?1. At a high rate of 3000 mA g^?1, its reversible capacity still remains at 537 mAh g^?1, superior to the uncoated counterpart (311 mAh g^?1). Moreover, amorphous Li₂O and Li₂CO₃ coatings are also similarly produced on Fe₂O₃ and NiO nanocrystallines, respectively, representing the general applicability of this mechanochemical approach.     

Lithium Titanate Tailored by Cathodically Induced Graphene for an Ultrafast Lithium Ion Battery

Nonoxidative cathodically induced graphene (CIG) here incorporates conductive agents for Li₄Ti₅O₁₂ (LTO) anode materials. The tailored LTO/CIG composite is fabricated by controlled hydrolysis of tetrabutyl titanate in the presence of nonoxidative defect‐free cathodically induced graphene (CIG) and oxalic acid in a mixed solvent of ethanol and water, followed by hydrothermal reaction and a calcination treatment. Due to the introduction of defect‐free graphene, the resulting LTO/CIG composite shows an excellent electrical conductivity (1.2 × 10^?4 S cm^?1) and Li⁺ diffusion coefficient (1.61 × 10^?12 cm² s^?1). As a result, the tuned LTO/CIG composite exhibits outstanding electrochemical performance, including excellent cycling stability (the capacity retention ratios after 500 cycles at 0.5 C is 96.2%) and a remarkable rate capability (162 mAh g^?1 at 10C, 126 mAh g^?1 at 100 C). A specific energy of 272 Wh kg^?1 at power of 136 W kg^?1 is observed when cycling against Li‐foil. Even during 36 s of charge/discharge, the specific energy of LTO/CIG composite remains at 166 Wh kg^?1.     

Li‐CO2 Batteries Efficiently Working at Ultra‐Low Temperatures

Lithium‐carbon dioxide (Li‐CO₂) batteries are considered promising energy‐storage systems in extreme environments with ultra‐high CO₂ concentrations, such as Mars with 96% CO₂ in the atmosphere, due to their potentially high specific energy densities. However, besides having ultra‐high CO₂ concentration, another vital but seemingly overlooked fact lies in that Mars is an extremely cold planet with an average temperature of approximately ?60 °C. The existing Li‐CO₂ batteries could work at room temperature or higher, but they will face severe performance degradation or even a complete failure once the ambient temperature falls below 0 °C. Herein, ultra‐low‐temperature Li‐CO₂ batteries are demonstrated by designing 1,3‐dioxolane‐based electrolyte and iridium‐based cathode, which show both a high deep discharge capacity of 8976 mAh g^?1 and a long lifespan of 150 cycles (1500 h) with a fixed 500 mAh g^?1 capacity per cycle at ?60 °C. The easy‐to‐decompose discharge products in small size on the cathode and the suppressed parasitic reactions both in the electrolyte and on the Li anode at low temperatures together contribute to the above high electrochemical performances.     

High‐Rate LiFePO4 Electrode Material Synthesized by a Novel Route from FePO4 · 4H2O

A LiFePO₄ material with ordered olivine structure is synthesized from amorphous FePO₄ · 4H₂O through a solid–liquid phase reaction using (NH₄)₂SO₃ as the reducing agent, followed by thermal conversion of the intermediate NH₄FePO₄ in the presence of LiCOOCH₃ · 2H₂O. Simultaneous thermogravimetric–differential thermal analysis indicates that the crystallization temperature of LiFePO₄ is about 437 °C. Ellipsoidal particle morphology of the resulting LiFePO₄ powder with a particle size mainly in the range 100–300 nm is observed by using scanning electron microscopy and transmission electron microscopy. As an electrode material for rechargeable lithium batteries, the LiFePO₄ sample delivers a discharge capacity of 167 mA h g^–1 at a constant current of 17 mA g^–1 (0.1 C rate; throughout this study n C rate means that rated capacity of LiFePO₄ (170 mA h g^–1) is charged or discharged completely in 1/n hours), approaching the theoretical value of 170 mA h g^–1. Moreover, the electrode shows excellent high‐rate charge and discharge capability and high electrochemical reversibility. No capacity loss can be observed up to 50 cycles under 5 C and 10 C rate conditions. With a conventional charge mode, that is, 5 C rate charging to 4.2 V and then keeping this voltage until the charge current is decreased to 0.1 C rate, a discharge capacity of ca. 134 mA h g^–1 and cycling efficiency of 99.2–99.6 % can be obtained at 5 C rate.     

FeO0.7F1.3/C Nanocomposite as a High‐Capacity Cathode Material for Sodium‐Ion Batteries

Searching high capacity cathode materials is one of the most important fields of the research and development of sodium‐ion batteries (SIBs). Here, we report a FeO_0.7F_1.3/C nanocomposite synthesized via a solution process as a new cathode material for SIBs. This material exhibits a high initial discharge capacity of 496 mAh g^?1 in a sodium cell at 50 °C. From the 3^rd to 50^th cycle, the capacity fading is only 0.14% per cycle (from 388 mAh g^?1 at 3^rd the cycle to 360 mAh g^?1 at the 50^th cycle), demonstrating superior cyclability. A high energy density of 650 Wh kg^?1 is obtained at the material level. The reaction mechanism studies of FeO_0.7F_1.3/C with sodium show a hybridized mechanism of both intercalation and conversion reaction.     

High‐Voltage LiNi0.45Cr0.1Mn1.45O4 Cathode with Superlong Cycle Performance for Wide Temperature Lithium‐Ion Batteries

Spinel LiNi_0.45Cr_0.1Mn_1.45O₄ synthesized by a scalable solution route combined by high temperature calcination is investigated as cathode for ultralong‐life lithium‐ion batteries in a wide operating temperature range. Scanning electron microscopy reveals homogeneous microsized polyhedral morphology with highly exposed {100} and {111} surfaces. The most highlighted result is that LiNi_0.45Cr_0.1Mn_1.45O₄ has extremely long cycle performance and high capacity retention at various temperatures (0, 25, 50 °C), indicating that Cr doping is a prospective approach to enable 5 V LiNi_0.5Mn_1.5O₄ (LNMO)‐based cathode materials with excellent cycling performances for commercial applications. After 1000 cycles, the capacity retention of LiNi_0.45Cr_0.1Mn_1.45O₄ is 100.30% and 82.75% at 0 °C and 25 °C at 1 C rate, respectively. Notably, over 350 cycles at 50 °C, the capacity retention of LiNi_0.45Cr_0.1Mn_1.45O₄ can maintain up to 91.49% at 1 C. All the values are comparable to pristine LNMO, which can be attributed to the elimination of Li_yNi_1?yO impurity phase, highly exposed {100} surfaces, less Mn³⁺ ions, and enhancement of ion and electron conductivity by Cr doping. Furthermore, an assembled LiNi_0.45Cr_0.1Mn_1.45O₄/Li₄Ti₅O₁₂ full cell delivers an initial discharge capacity of 101 mA h g^?1, meanwhile the capacity retention is 82.07% after 100 cycles.