A Self‐Healing Integrated All‐in‐One Zinc‐Ion Battery

The self‐healing of zinc‐ion batteries (ZIBs) will not only significantly improve the durability and extend the lifetime of devices, but also decrease electronic waste and economic cost. A poly(vinyl alcohol)/zinc trifluoromethanesulfonate (PVA/Zn(CF₃SO₃)₂) hydrogel electrolyte was fabricated by a facile freeze/thaw strategy. PVA/Zn(CF₃SO₃)₂ hydrogels possess excellent ionic conductivity and stable electrochemical performance. Such hydrogel electrolytes can autonomously self‐heal by hydrogen bonding without any external stimulus. All‐in‐one integrated ZIBs can be assembled by incorporating the cathode, separator, and anode into hydrogel matrix since the fabrication of PVA/Zn(CF₃SO₃)₂ hydrogel is a process of converting the liquid to quasi‐solid state. The ZIBs show an outstanding self‐healing and can recover electrochemical performance completely even after several cutting/healing cycles.     

Ruthenium‐Oxide‐Coated Sodium Vanadium Fluorophosphate Nanowires as High‐Power Cathode Materials for Sodium‐Ion Batteries

Sodium‐ion batteries are a very promising alternative to lithium‐ion batteries because of their reliance on an abundant supply of sodium salts, environmental benignity, and low cost. However, the low rate capability and poor long‐term stability still hinder their practical application. A cathode material, formed of RuO₂‐coated Na₃V₂O₂(PO₄)₂F nanowires, has a 50 nm diameter with the space group of I4/mmm. When used as a cathode material for Na‐ion batteries, a reversible capacity of 120 mAh g^?1 at 1 C and 95 mAh g^?1 at 20 C can be achieved after 1000 charge–discharge cycles. The ultrahigh rate capability and enhanced cycling stability are comparable with high performance lithium cathodes. Combining first principles computational investigation with experimental observations, the excellent performance can be attributed to the uniform and highly conductive RuO₂ coating and the preferred growth of the (002) plane in the Na₃V₂O₂(PO₄)₂F nanowires.     

Synthesis of Single‐Crystalline Spinel LiMn2O4 Nanorods for Lithium‐Ion Batteries with High Rate Capability and Long Cycle Life

The long‐standing challenge associated with capacity fading of spinel LiMn₂O₄ cathode material for lithium‐ion batteries is investigated. Single‐crystalline spinel LiMn₂O₄ nanorods were successfully synthesized by a template‐engaged method. Porous Mn₃O₄ nanorods were used as self‐sacrificial templates, into which LiOH was infiltrated by a vacuum‐assisted impregnation route. When used as cathode materials for lithium‐ion batteries, the spinel LiMn₂O₄ nanorods exhibited superior long cycle life owing to the one‐dimensional nanorod structure, single‐crystallinity, and Li‐rich effect. LiMn₂O₄ nanorods retained 95.6 % of the initial capacity after 1000 cycles at 3C rate. In particular, the nanorod morphology of the spinel LiMn₂O₄ was well‐preserved after a long‐term cycling, suggesting the ultrahigh structural stability of the single crystalline spinel LiMn₂O₄ nanorods. This result shows the promising applications of single‐crystalline spinel LiMn₂O₄ nanorods as cathode materials for lithium‐ion batteries with high rate capability and long cycle life.     

An Intrinsically Self‐Healing NiCo||Zn Rechargeable Battery with a Self‐Healable Ferric‐Ion‐Crosslinking Sodium Polyacrylate Hydrogel Electrolyte

Self‐healing solid‐state aqueous rechargeable NiCo||Zn batteries are inherently safe and have a high energy density and mechanical robustness. However, the self‐healability of solid‐state batteries has only been realized by a few studies in which electron/ion‐inactive self‐healable substrates are utilized. This arises from the lack of self‐healable electrolytes. Now an intrinsically self‐healing battery has been designed that utilizes a new electrolyte that is intrinsically self‐healable. Sodium polyacrylate hydrogel chains are crosslinked by ferric ions to promote dynamic reconstruction of an integral network. These non‐covalent crosslinkers can form ionic bonds to reconnect damaged surfaces when the hydrogel is cut off, providing an ultimate solution to the intrinsic self‐healability problem of batteries. As a result, this NiCo||Zn battery with this hydrogel electrolyte can be autonomically self‐healed with over 87 % of capacity retained after 4 cycles of breaking/healing.     

A redox‐active polythiophene‐modified separator for safety control of lithium‐ion batteries

A potential‐sensitive separator is prepared simply by incorporating a redox‐active poly(3‐butylthiophene) (P3BT) into the micropores of a commercial porous polyolefin film and tested for overcharge protection of LiFePO₄/Li₄Ti₅O₁₂ lithium‐ion batteries. The experimental results demonstrate that owing to the reversible p‐doping and dedoping of the redox‐active P3BT polymer embedded in the separator with the changes of the cathode potential from an overcharge state to a normal operating state, this type of separator can reversibly switch between electronically insulating state and conductive state to maintain the charge voltage of LiFePO₄/Li₄Ti₅O₁₂ cells at a safety value of ≤2.4 V, and thus protecting the cell from voltage runaway. As this type of the separators works reversibly and has no negative impact on the battery performances, it can be used as an internal and self‐protecting mechanism for commercial lithium‐ion batteries and other rechargeable batteries. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2013 , 51, 1487–1493     

Self‐Assembling Synthesis of Free‐standing Nanoporous Graphene–Transition‐Metal Oxide Flexible Electrodes for High‐Performance Lithium‐Ion Batteries and Supercapacitors

The synthesis of nanoporous graphene by a convenient carbon nanofiber assisted self‐assembly approach is reported. Porous structures with large pore volumes, high surface areas, and well‐controlled pore sizes were achieved by employing spherical silica as hard templates with different diameters. Through a general wet‐immersion method, transition‐metal oxide (Fe₃O₄, Co₃O₄, NiO) nanocrystals can be easily loaded into nanoporous graphene papers to form three‐dimensional flexible nanoarchitectures. When directly applied as electrodes in lithium‐ion batteries and supercapacitors, the materials exhibited superior electrochemical performances, including an ultra‐high specific capacity, an extended long cycle life, and a high rate capability. In particular, nanoporous Fe₃O₄–graphene composites can deliver a reversible specific capacity of 1427.5 mAh g^?1 at a high current density of 1000 mA g^?1 as anode materials in lithium‐ion batteries. Furthermore, nanoporous Co₃O₄–graphene composites achieved a high supercapacitance of 424.2 F g^?1. This work demonstrated that the as‐developed freestanding nanoporous graphene papers could have significant potential for energy storage and conversion applications.     

Wintersweet‐Flower‐Like CoFe2O4/MWCNTs Hybrid Material for High‐Capacity Reversible Lithium Storage

CoFe₂O₄/multiwalled carbon nanotubes (MWCNTs) hybrid materials were synthesized by a hydrothermal method. Field emission scanning electron microscopy and transmission electron microscopy analysis confirmed the morphology of the as‐prepared hybrid material resembling wintersweet flower “buds on branches”, in which CoFe₂O₄ nanoclusters, consisting of nanocrystals with a size of 5–10 nm, are anchored along carbon nanotubes. When applied as an anode material in lithium ion batteries, the CoFe₂O₄/MWCNTs hybrid material exhibited a high performance for reversible lithium storage. In particular, the hybrid anode material delivered reversible lithium storage capacities of 809, 765, 539, and 359 mA h g^?1 at current densities of 180, 450, 900, and 1800 mA g^?1, respectively. The superior performance of CoFe₂O₄/MWCNTs hybrid materials could be ascribed to the synergistic pinning effect of the wintersweet‐flower‐like nanoarchitecture. This strategy could also be applied to synthesize other metal oxide/CNTs hybrid materials as high‐capacity anode materials for lithium ion batteries.     

In Situ Growth of Hierarchical SnO2 Nanosheet Arrays on 3D Macroporous Substrates as High‐Performance Electrodes

Finding out how to overcome the self‐aggregation of nanostructured electrode materials is a very important issue in lithium‐ion battery technology. Herein, by an in situ construction strategy, hierarchical SnO₂ nanosheet architectures have been fabricated on a three‐dimensional macroporous substrate, and thus the aggregation of the SnO₂ nanosheets was effectively prevented. The as‐prepared hierarchical SnO₂ nanoarchitectures on the nickel foam can be directly used as an integrated anode for lithium‐ion batteries without the addition of other ancillary materials such as carbon black or binder. In view of their apparent advantages, such as high electroactive surface area, ultrathin sheet, robust mechanical strength, shorter ion and electron transport path, and the specific macroporous structure, the hierarchical SnO₂ nanosheets exhibit excellent lithium‐storage performance. Our present growth approach offers a new technique for the design and synthesis of metal oxide hierarchical nanoarrays that are promising for electrochemical energy‐storage electrodes without carbon black and binder.     

TiO2 Microboxes with Controlled Internal Porosity for High‐Performance Lithium Storage

Titanium dioxide (TiO₂) is considered a promising anode material for high‐power lithium ion batteries (LIBs) because of its low cost, high thermal/chemical stability, and good safety performance without solid electrolyte interface formation. However, the poor electronic conductivity and low lithium ion diffusivity of TiO₂ result in poor cyclability and lithium ion depletion at high current rates, which hinder them from practical applications. Herein we demonstrate that hierarchically structured TiO₂ microboxes with controlled internal porosity can address the aforementioned problems for high‐power, long‐life LIB anodes. A self‐templating method for the synthesis of mesoporous microboxes was developed through Na₂EDTA‐assisted ion exchange of CaTiO₃ microcubes. The resulting TiO₂ nanorods were organized into microboxes that resemble the microcube precursors. This nanostructured TiO₂ material has superior lithium storage properties with a capacity of 187 mAh g⁻¹ after 300 cycles at 1 C and good rate capabilities up to 20 C.     

Natural Soft/Rigid Superlattices as Anodes for High‐Performance Lithium‐Ion Batteries

Volume expansion and poor conductivity are two major obstacles that hinder the pursuit of the lithium‐ion batteries with long cycling life and high power density. Herein, we highlight a misfit compound PbNbS₃ with a soft/rigid superlattice structure, confirmed by scanning tunneling microscopy and electrochemical characterization, as a promising anode material for high performance lithium‐ion batteries with optimized capacity, stability, and conductivity. The soft PbS sublayers primarily react with lithium, endowing capacity and preventing decomposition of the superlattice structure, while the rigid NbS₂ sublayers support the skeleton and enhance the migration of electrons and lithium ions, as a result leading to a specific capacity of 710 mAh g^?1 at 100 mA g^?1, which is 1.6 times of NbS₂ and 3.9 times of PbS. Our finding reveals the competitive strategy of soft/rigid structure in lithium‐ion batteries and broadens the horizons of single‐phase anode material design.     

Deep‐Eutectic‐Solvent‐Based Self‐Healing Polymer Electrolyte for Safe and Long‐Life Lithium‐Metal Batteries

The deployment of high‐energy‐density lithium‐metal batteries has been greatly impeded by Li dendrite growth and safety concerns originating from flammable liquid electrolytes. Herein, we report a stable quasi‐solid‐state Li metal battery with a deep eutectic solvent (DES)‐based self‐healing polymer (DSP) electrolyte. This electrolyte was fabricated in a facile manner by in situ copolymerization of 2‐(3‐(6‐methyl‐4‐oxo‐1,4‐dihydropyrimidin‐2‐yl)ureido)ethyl methacrylate (UPyMA) and pentaerythritol tetraacrylate (PETEA) monomers in a DES‐based electrolyte containing fluoroethylene carbonate (FEC) as an additive. The well‐designed DSP electrolyte simultaneously possesses non‐flammability, high ionic conductivity and electrochemical stability, and dendrite‐free Li plating. When applied in Li metal batteries with a LiMn₂O₄ cathode, the DSP electrolyte effectively suppressed manganese dissolution from the cathode and enabled high‐capacity and a long lifespan at room and elevated temperatures.     

Formation of Triple‐Shelled Molybdenum–Polydopamine Hollow Spheres and Their Conversion into MoO2/Carbon Composite Hollow Spheres for Lithium‐Ion Batteries

Unique triple‐shelled Mo‐polydopamine (Mo‐PDA) hollow spheres are synthesized through a facile solvothermal process. A sequential self‐templating mechanism for the multi‐shell formation is proposed, and the number of shells can be adjusted by tuning the size of the Mo‐glycerate templates. These triple‐shelled Mo‐PDA hollow spheres can be converted to triple‐shelled MoO₂/carbon composite hollow spheres by thermal treatment. Owing to the unique multi‐shells and hollow interior, the as‐prepared MoO₂/carbon composite hollow spheres exhibit appealing performance as an anode material for lithium‐ion batteries, delivering a high capacity of ca. 580 mAh g^?1 at 0.5 A g^?1 with good rate capability and long cycle life.     

Rational Design of an Ionic Liquid‐Based Electrolyte with High Ionic Conductivity Towards Safe Lithium/Lithium‐Ion Batteries

It is a very urgent and important task to improve the safety and high‐temperature performance of lithium/lithium‐ion batteries (LIBs). Here, a novel ionic liquid, 1‐(2‐ethoxyethyl)‐1‐methylpyrrolidinium bis(trifluoromethylsulfonyl)imide (PYR_1(2o2)TFSI), was designed and synthesized, and then mixed with dimethyl carbonate (DMC) as appropriate solvent and LiTFSI lithium salt to produce an electrolyte with high ionic conductivity for safe LIBs. Various characterizations and tests show that the highly flexible ether group could markedly reduce the viscosity and provide coordination sites for Li‐ion, and the DMC could reduce the viscosity and effectively enhance the Li‐ion transport rate and transference number. The electrolyte exhibits excellent electrochemical performance in Li/LiFeO₄ cells at room temperature as well as at a high temperature of 60 °C. More importantly, with the addition of DMC, the IL‐based electrolyte remains nonflammable and appropriate DMC can effectively inhibit the growth of lithium dendrites. Our present work may provide an attractive and promising strategy for high performance and safety of both lithium and lithium‐ion batteries.     

Revisiting Surface Modification of Graphite: Dual‐Layer Coating for High‐Performance Lithium Battery Anode Materials

Surface modification of electrode active materials has garnered considerable attention as a facile way to meet stringent requirements of advanced lithium‐ion batteries. Here, we demonstrated a new coating strategy based on dual layers comprising antimony‐doped tin oxide (ATO) nanoparticles and carbon. The ATO nanoparticles are synthesized via a hydrothermal method and act as electronically conductive/electrochemically active materials. The as‐synthesized ATO nanoparticles are introduced on natural graphite along with citric acid used as a carbon precursor. After carbonization, the carbon/ATO‐decorated natural graphite (c/ATO‐NG) is produced. In the (carbon/ATO) dual‐layer coating, the ATO nanoparticles coupled with the carbon layer exhibit unprecedented synergistic effects. The resultant c/ATO‐NG anode materials display significant improvements in capacity (530 mA h g^?1), cycling retention (capacity retention of 98.1 % after 50 cycles at a rate of C/5), and low electrode swelling (volume expansion of 38 % after 100 cycles) which outperform that of typical graphite materials. Furthermore, a full‐cell consisting of a c/ATO‐NG anode and an LiNi_0.5Mn_1.5O₄ cathode presents excellent cycle retention (capacity retention of >80 % after 100 cycles). We envision that the dual‐layer coating concept proposed herein opens a new route toward high‐performance anode materials for lithium‐ion batteries.     

Structure Design and Performance of LiNixCoyMn1‐x‐yO2 Cathode Materials for Lithium‐ion Batteries: A Review

Lithium‐ion batteries are now considered to be the technology of choice for future hybrid electric and full electric vehicles to address global warming. One of the challenges for improving the performance of lithium ion batteries to meet increasingly demanding requirements for energy storage is the development of suitable cathode materials. The recent advancement of lithium nickel cobalt manganese oxides are investigated as advanced positive cathode materials for lithium‐ion batteries. This review aims at providing the reader with an understanding of the critical scientific challenges facing the development of LiNi_xCo_yMn_1‐x‐yO₂ materials, the latest developments in crystal structure, synthesis methods, and structure designs to unravel the mechanisms of charge and mass transport processes associated with battery performance, and the outlook for future‐generation batteries that exploit gradient structures materials for significantly improved performance to meet the ever‐increasing demands of emerging technologies.     

Self‐Templated Formation of Uniform NiCo2O4 Hollow Spheres with Complex Interior Structures for Lithium‐Ion Batteries and Supercapacitors

Despite the significant advancement in preparing metal oxide hollow structures, most approaches rely on template‐based multistep procedures for tailoring the interior structure. In this work, we develop a new generally applicable strategy toward the synthesis of mixed‐metal‐oxide complex hollow spheres. Starting with metal glycerate solid spheres, we show that subsequent thermal annealing in air leads to the formation of complex hollow spheres of the resulting metal oxide. We demonstrate the concept by synthesizing highly uniform NiCo₂O₄ hollow spheres with a complex interior structure. With the small primary building nanoparticles, high structural integrity, complex interior architectures, and enlarged surface area, these unique NiCo₂O₄ hollow spheres exhibit superior electrochemical performances as advanced electrode materials for both lithium‐ion batteries and supercapacitors. This approach can be an efficient self‐templated strategy for the preparation of mixed‐metal‐oxide hollow spheres with complex interior structures and functionalities.     

A Low‐Cost and Environmentally Friendly Mixed Polyanionic Cathode for Sodium‐Ion Storage

Sodium‐ion batteries (NIBs) are the most promising alternatives to lithium‐ion batteries in the development of renewable energy sources. The advancement of NIBs depends on the exploration of new electrode materials and fundamental understanding of working mechanisms. Herein, via experimental and simulation methods, we develop a mixed polyanionic compound, Na₂Fe(C₂O₄)SO₄?H₂O, as a cathode for NIBs. Thanks to its rigid three dimensional framework and the combined inductive effects from oxalate and sulfate, it delivered reversible Na insertion/desertion at average discharging voltages of 3.5 and 3.1 V for 500 cycles with Coulombic efficiencies of ca. 99 %. In situ synchrotron X‐ray measurements and DFT calculations demonstrate the Fe²⁺/Fe³⁺ redox reactions contribute to electron compensation during Na⁺ desertion/insertion. The study suggests mixed polyanionic frameworks may provide promising materials for Na ion storage with the merits of low cost and environmental friendliness.     

Nitrogen‐Doped Carbon Embedded MoS2 Microspheres as Advanced Anodes for Lithium‐ and Sodium‐Ion Batteries

Rational design and synthesis of advanced anode materials are extremely important for high‐performance lithium‐ion and sodium‐ion batteries. Herein, a simple one‐step hydrothermal method is developed for fabrication of N‐C@MoS₂ microspheres with the help of polyurethane as carbon and nitrogen sources. The MoS₂ microspheres are composed of MoS₂ nanoflakes, which are wrapped by an N‐doped carbon layer. Owing to its unique structural features, the N‐C@MoS₂ microspheres exhibit greatly enhanced lithium‐ and sodium‐storage performances including a high specific capacity, high rate capability, and excellent capacity retention. Additionally, the developed polyurethane‐assisted hydrothermal method could be useful for the construction of many other high‐capacity metal oxide/sulfide composite electrode materials for energy storage.     

ChemInform Abstract: Evaluation of Tavorite‐Structured Cathode Materials for Lithium‐Ion Batteries Using High‐Throughput Computing.

Tavorite‐structured oxyphosphates, fluorophosphates, oxysulfates, and fluorosulfates are evaluated for use as cathode materials in lithium ion batteries and activation energies for lithium diffusion through LiVO(PO₄), LiV(PO₄)F, and LiFe(SO₄)F are calculated.     

Flexible Aqueous Lithium‐Ion Battery with High Safety and Large Volumetric Energy Density

A flexible and wearable aqueous lithium‐ion battery is introduced based on spinel Li_1.1Mn₂O₄ cathode and a carbon‐coated NASICON‐type LiTi₂(PO₄)₃ anode (NASICON=sodium‐ion super ionic conductor). Energy densities of 63 Wh kg^?1 or 124 mWh cm^?3 and power densities of 3 275 W kg^?1 or 11.1 W cm^?3 can be obtained, which are seven times larger than the largest reported till now. The full cell can keep its capacity without significant loss under different bending states, which shows excellent flexibility. Furthermore, two such flexible cells in series with an operation voltage of 4 V can be compatible with current nonaqueous Li‐ion batteries. Therefore, such a flexible cell can potentially be put into practical applications for wearable electronics. In addition, a self‐chargeable unit is realized by integrating a single flexible aqueous Li‐ion battery with a commercial flexible solar cell, which may facilitate the long‐time outdoor operation of flexible and wearable electronic devices.