Polarity‐Switchable Symmetric Graphite Batteries with High Energy and High Power Densities

Multifunctional batteries with enhanced safety performance have received considerable attention for their applications at extreme conditions. However, few batteries can endure a mix‐up of battery polarity during charging, a common wrong operation of rechargeable batteries. Herein, a polarity‐switchable battery based on the switchable intercalation feature of graphite is demonstrated. The unique redox‐amphoteric intercalation behavior of graphite allows a reversible switching of graphite between anode and cathode, thus enabling polarity‐switchable symmetric graphite batteries. The large potential gap between anion and cation intercalation delivers a high midpoint device voltage (≈average voltage) of ≈4.5 V. Further, both the graphite anode and cathode are kinetically activated during the polarity switching. Consequently, polarity‐switchable symmetric graphite batteries exhibit a remarkable cycling stability (96% capacity retention after 500 cycles), a high power density of 8.66 kW kg^?1, and a high energy density of 227 Wh kg^?1 (calculated based on the total weight of active materials in both anode and cathode), which are superior to other symmetric batteries and recently reported dual‐graphite or dual‐carbon batteries. This work will inspire the development of new multifunctional energy‐storage devices based on novel materials and electrolyte systems.     

Bamboo‐Like Nitrogen‐Doped Carbon Nanotube Forests as Durable Metal‐Free Catalysts for Self‐Powered Flexible Li–CO2 Batteries

The Li–CO₂ battery is a promising energy storage device for wearable electronics due to its long discharge plateau, high energy density, and environmental friendliness. However, its utilization is largely hindered by poor cyclability and mechanical rigidity due to the lack of a flexible and durable catalyst electrode. Herein, flexible fiber‐shaped Li–CO₂ batteries with ultralong cycle‐life, high rate capability, and large specific capacity are fabricated, employing bamboo‐like N‐doped carbon nanotube fiber (B‐NCNT) as flexible, durable metal‐free catalysts for both CO₂ reduction and evolution reactions. Benefiting from high N‐doping with abundant pyridinic groups, rich defects, and active sites of the periodic bamboo‐like nodes, the fabricated Li–CO₂ battery shows outstanding electrochemical performance with high full‐discharge capacity of 23 328 mAh g^?1, high rate capability with a low potential gap up to 1.96 V at a current density of 1000 mA g^?1, stability over 360 cycles, and good flexibility. Meanwhile, the bifunctional B‐NCNT is used as the counter electrode for a fiber‐shaped dye‐sensitized solar cell to fabricate a self‐powered fiber‐shaped Li–CO₂ battery with overall photochemical–electric energy conversion efficiency of up to 4.6%. Along with a stable voltage output, this design demonstrates great adaptability and application potentiality in wearable electronics with a breath monitor as an example.     

High‐Performance Integrated Self‐Package Flexible Li–O2 Battery Based on Stable Composite Anode and Flexible Gas Diffusion Layer

With the rising development of flexible and wearable electronics, corresponding flexible energy storage devices with high energy density are required to provide a sustainable energy supply. Theoretically, rechargeable flexible Li–O₂ batteries can provide high specific energy density; however, there are only a few reports on the construction of flexible Li–O₂ batteries. Conventional flexible Li–O₂ batteries possess a loose battery structure, which prevents flexibility and stability. The low mechanical strength of the gas diffusion layer and anode also lead to a flexible Li–O₂ battery with poor mechanical properties. All these attributes limit their practical applications. Herein, the authors develop an integrated flexible Li–O₂ battery based on a high‐fatigue‐resistance anode and a novel flexible stretchable gas diffusion layer. Owing to the synergistic effect of the stable electrocatalytic activity and hierarchical 3D interconnected network structure of the free‐standing cathode, the obtained flexible Li–O₂ batteries exhibit superior electrochemical performance, including a high specific capacity, an excellent rate capability, and exceptional cycle stability. Furthermore, benefitting from the above advantages, the as‐fabricated flexible batteries can realize excellent mechanical and electrochemical stability. Even after a thousand cycles of the bending process, the flexible Li–O₂ battery can still possess a stable open‐circuit voltage, a high specific capacity, and a durable cycle performance.     

A Quasi‐Solid‐State Flexible Fiber‐Shaped Li–CO2 Battery with Low Overpotential and High Energy Efficiency

The rapid development of wearable electronics requires a revolution of power accessories regarding flexibility and energy density. The Li–CO₂ battery was recently proposed as a novel and promising candidate for next‐generation energy‐storage systems. However, the current Li–CO₂ batteries usually suffer from the difficulties of poor stability, low energy efficiency, and leakage of liquid electrolyte, and few flexible Li–CO₂ batteries for wearable electronics have been reported so far. Herein, a quasi‐solid‐state flexible fiber‐shaped Li–CO₂ battery with low overpotential and high energy efficiency, by employing ultrafine Mo₂C nanoparticles anchored on a carbon nanotube (CNT) cloth freestanding hybrid film as the cathode, is demonstrated. Due to the synergistic effects of the CNT substrate and Mo₂C catalyst, it achieves a low charge potential below 3.4 V, a high energy efficiency of ≈80%, and can be reversibly discharged and charged for 40 cycles. Experimental results and theoretical simulation show that the intermediate discharge product Li₂C₂O₄ stabilized by Mo₂C via coordinative electrons transfer should be responsible for the reduction of overpotential. The as‐fabricated quasi‐solid‐state flexible fiber‐shaped Li–CO₂ battery can also keep working normally even under various deformation conditions, giving it great potential of becoming an advanced energy accessory for wearable electronics.     

Magnesium Storage Performance and Mechanism of 2D‐Ultrathin Nanosheet‐Assembled Spinel MgIn2S4 Cathode for High‐Temperature Mg Batteries

Magnesium batteries have the potential to be a next generation battery with large capability and high safety, owing to the high abundance, great volumetric energy density, and reversible dendrite‐free capability of Mg anodes. However, the lack of a stable high‐voltage electrolyte, and the sluggish Mg‐ion diffusion in lattices and through interfaces limit the practical uses of Mg batteries. Herein, a spinel MgIn₂S₄ microflower‐like material assembled by 2D‐ultrathin (≈5.0 nm) nanosheets is reported and first used as a cathode material for high‐temperature Mg batteries with an ionic liquid electrolyte. The nonflammable ionic liquid electrolyte ensure the safety under high temperatures. As prepared MgIn₂S₄ exhibits wide‐temperature‐range adaptability (50–150 °C), ultrahigh capacity (≈500 mAh g^?1 under 1.2 V vs Mg/Mg²⁺), fast Mg²⁺ diffusibility (≈2.0 × 10^?8 cm² s^?1), and excellent cyclability (without capacity decay after 450 cycles). These excellent electrochemical properties are due to the fast kinetics of magnesium by the 2D nanosheets spinel structure and safe high‐temperature operation environment. From ex situ X‐ray diffraction and transmission electron microscopy measurements, a conversion reaction of the Mg²⁺ storage mechanism is found. The excellent performance and superior security make it promising in high‐temperature batteries for practical applications.     

Bubble‐Sheet‐Like Interface Design with an Ultrastable Solid Electrolyte Layer for High‐Performance Dual‐Ion Batteries

In this work, a bubble‐sheet‐like hollow interface design on Al foil anode to improve the cycling stability and rate performance of aluminum anode based dual‐ion battery is reported, in which, a carbon‐coated hollow aluminum anode is used as both anode materials and current collector. This anode structure can guide the alloying position inside the hollow nanospheres, and also confine the alloy sizes within the hollow nanospheres, resulting in significantly restricted volumetric expansion and ultrastable solid electrolyte interface (SEI). As a result, the battery demonstrates an excellent long‐term cycling stability within 1500 cycles with ≈99% capacity retention at 2 C. Moreover, this cell displays an energy density of 169 Wh kg^?1 even at high power density of 2113 W kg^?1 (10 C, charge and discharge within 6 min), which is much higher than most of conventional lithium ion batteries. The interfacial engineering strategy shown in this work to stabilize SEI layer and control the alloy forming position could be generalized to promote the research development of metal anodes based battery systems.     

Achieving Ultrahigh Energy Density and Long Durability in a Flexible Rechargeable Quasi‐Solid‐State Zn–MnO2 Battery

Advanced flexible batteries with high energy density and long cycle life are an important research target. Herein, the first paradigm of a high‐performance and stable flexible rechargeable quasi‐solid‐state Zn–MnO₂ battery is constructed by engineering MnO₂ electrodes and gel electrolyte. Benefiting from a poly(3,4‐ethylenedioxythiophene) (PEDOT) buffer layer and a Mn²⁺‐based neutral electrolyte, the fabricated Zn–MnO₂@PEDOT battery presents a remarkable capacity of 366.6 mA h g^?1 and good cycling performance (83.7% after 300 cycles) in aqueous electrolyte. More importantly, when using PVA/ZnCl₂/MnSO₄ gel as electrolyte, the as‐fabricated quasi‐solid‐state Zn–MnO₂@PEDOT battery remains highly rechargeable, maintaining more than 77.7% of its initial capacity and nearly 100% Coulombic efficiency after 300 cycles. Moreover, this flexible quasi‐solid‐state Zn–MnO₂ battery achieves an admirable energy density of 504.9 W h kg^?1 (33.95 mW h cm^?3), together with a peak power density of 8.6 kW kg^?1, substantially higher than most recently reported flexible energy‐storage devices. With the merits of impressive energy density and durability, this highly flexible rechargeable Zn–MnO₂ battery opens new opportunities for powering portable and wearable electronics.     

High‐Performance Flexible Freestanding Anode with Hierarchical 3D Carbon‐Networks/Fe7S8/Graphene for Applicable Sodium‐Ion Batteries

Sodium‐ion batteries (SIBs) have gained tremendous interest for grid scale energy storage system and power energy batteries. However, the current researches of anode for SIBs still face the critical issues of low areal capacity, limited cycle life, and low initial coulombic efficiency for practical application perspective. To solve this issue, a kind of hierarchical 3D carbon‐networks/Fe₇S₈/graphene (CFG) is designed and synthesized as freestanding anode, which is constructed with Fe₇S₈ microparticles well‐welded on 3D‐crosslinked carbon‐networks and embedded in highly conductive graphene film, via a facile and scalable synthetic method. The as‐prepared freestanding electrode CFG represents high areal capacity (2.12 mAh cm^?2 at 0.25 mA cm^?2) and excellent cycle stability of 5000 cycles (0.0095% capacity decay per cycle). The assembled all‐flexible sodium‐ion battery delivers remarkable performance (high areal capacity of 1.42 mAh cm^?2 at 0.3 mA cm^?2 and superior energy density of 144 Wh kg^?1), which are very close to the requirement of practical application. This work not only enlightens the material design and electrode engineering, but also provides a new kind of freestanding high energy density anode with great potential application prospective for SIBs.     

An Ultrastable and High‐Performance Flexible Fiber‐Shaped Ni–Zn Battery based on a Ni–NiO Heterostructured Nanosheet Cathode

Currently, the main bottleneck for the widespread application of Ni–Zn batteries is their poor cycling stability as a result of the irreversibility of the Ni‐based cathode and dendrite formation of the Zn anode during the charging–discharging processes. Herein, a highly rechargeable, flexible, fiber‐shaped Ni–Zn battery with impressive electrochemical performance is rationally demonstrated by employing Ni–NiO heterostructured nanosheets as the cathode. Benefiting from the improved conductivity and enhanced electroactivity of the Ni–NiO heterojunction nanosheet cathode, the as‐fabricated fiber‐shaped Ni–NiO//Zn battery displays high capacity and admirable rate capability. More importantly, this Ni–NiO//Zn battery shows unprecedented cyclic durability both in aqueous (96.6% capacity retention after 10 000 cycles) and polymer (almost no capacity attenuation after 10 000 cycles at 22.2 A g^?1) electrolytes. Moreover, a peak energy density of 6.6 µWh cm^?2, together with a remarkable power density of 20.2 mW cm^?2, is achieved by the flexible quasi‐solid‐state fiber‐shaped Ni–NiO//Zn battery, outperforming most reported fiber‐shaped energy‐storage devices. Such a novel concept of a fiber‐shaped Ni–Zn battery with impressive stability will greatly enrich the flexible energy‐storage technologies for future portable/wearable electronic applications.     

Flexible 1D Batteries: Recent Progress and Prospects

With the rapid development of wearable and portable electronics, flexible and stretchable energy storage devices to power them are rapidly emerging. Among numerous flexible energy storage technologies, flexible batteries are considered as the most favorable candidate due to their high energy density and long cycle life. In particular, flexible 1D batteries with the unique advantages of miniaturization, adaptability, and weavability are expected to be a part of such applications. The development of 1D batteries, including lithium-ion batteries, zinc-ion batteries, zinc–air batteries, and lithium–air batteries, is comprehensively summarized, with particular emphasis on electrode preparation, battery design, and battery properties. In addition, the remaining challenges to the commercialization of current 1D batteries and prospective opportunities in the field are discussed.     

Lithium Titanate Cuboid Arrays Grown on Carbon Fiber Cloth for High‐Rate Flexible Lithium‐Ion Batteries

High‐rate performance flexible lithium‐ion batteries are desirable for the realization of wearable electronics. The flexibility of the electrode in the battery is a key requirement for this technology. In the present work, spinel lithium titanate (Li₄Ti₅O₁₂, LTO) cuboid arrays are grown on flexible carbon fiber cloth (CFC) to fabricate a binder‐free composite electrode (LTO@CFC) for flexible lithium‐ion batteries. Experimental results show that the LTO@CFC electrode exhibits a remarkably high‐rate performance with a capacity of 105.8 mAh g^?1 at 50C and an excellent electrochemical stability against cycling (only 2.2% capacity loss after 1000 cycles at 10C). A flexible full cell fabricated with the LTO@CFC as the anode and LiNi_0.5Mn_1.5O₄ coated on Al foil as the cathode displays a reversible capacity of 109.1 mAh g^?1 at 10C, an excellent stability against cycling and a great mechanical stability against bending. The observed high‐rate performance of the LTO@CFC electrode is due to its unique corn‐like architecture with LTO cuboid arrays (corn kernels) grown on CFC (corn cob). This work presents a new approach to preparing LTO‐based composite electrodes with an architecture favorable for ion and electron transport for flexible energy storage devices.     

A Carbonyl Compound‐Based Flexible Cathode with Superior Rate Performance and Cyclic Stability for Flexible Lithium‐Ion Batteries

A sulfur‐linked carbonyl‐based poly(2,5‐dihydroxyl‐1,4‐benzoquinonyl sulfide) (PDHBQS) compound is synthesized and used as cathode material for lithium‐ion batteries (LIBs). Flexible binder‐free composite cathode with single‐wall carbon nanotubes (PDHBQS–SWCNTs) is then fabricated through vacuum filtration method with SWCNTs. Electrochemical measurements show that PDHBQS–SWCNTs cathode can deliver a discharge capacity of 182 mA h g⁻¹ (0.9 mA h cm⁻²) at a current rate of 50 mA g⁻¹ and a potential window of 1.5 V–3.5 V. The cathode delivers a capacity of 75 mA h g⁻¹ (0.47 mA h cm⁻²) at 5000 mA g⁻¹, which confirms its good rate performance at high current density. PDHBQS–SWCNTs flexible cathode retains 89% of its initial capacity at 250 mA g⁻¹ after 500 charge–discharge cycles. Furthermore, large‐area (28 cm²) flexible batteries based on PDHBQS–SWCNTs cathode and lithium foils anode are also assembled. The flexible battery shows good electrochemical activities with continuous bending, which retains 88% of its initial discharge capacity after 2000 bending cycles. The significant capacity, high rate performance, superior cyclic performance, and good flexibility make this material a promising candidate for a future application of flexible LIBs.     

Graphene Caging Silicon Particles for High‐Performance Lithium‐Ion Batteries

Silicon holds great promise as an anode material for lithium‐ion batteries with higher energy density; its implication, however, is limited by rapid capacity fading. A catalytic growth of graphene cages on composite particles of magnesium oxide and silicon, which are made by magnesiothermic reduction reaction of silica particles, is reported herein. Catalyzed by the magnesium oxide, graphene cages can be conformally grown onto the composite particles, leading to the formation of hollow graphene‐encapsulated Si particles. Such materials exhibit excellent lithium storage properties in terms of high specific capacity, remarkable rate capability (890 mAh g^?1 at 5 A g^?1), and good cycling retention over 200 cycles with consistently high coulombic efficiency at a current density of 1 A g^?1. A full battery test using LiCoO₂ as the cathode demonstrates a high energy density of 329 Wh kg^?1.     

Defect‐Enriched Nitrogen Doped–Graphene Quantum Dots Engineered NiCo2S4 Nanoarray as High‐Efficiency Bifunctional Catalyst for Flexible Zn‐Air Battery

Flexible Zn‐air batteries have recently emerged as one of the key energy storage systems of wearable/portable electronic devices, drawing enormous attention due to the high theoretical energy density, flat working voltage, low cost, and excellent safety. However, the majority of the previously reported flexible Zn‐air batteries encounter problems such as sluggish oxygen reaction kinetics, inferior long‐term durability, and poor flexibility induced by the rigid nature of the air cathode, all of which severely hinder their practical applications. Herein, a defect‐enriched nitrogen doped–graphene quantum dots (N‐GQDs) engineered 3D NiCo₂S₄ nanoarray is developed by a facile chemical sulfuration and subsequent electrophoretic deposition process. The as‐fabricated N‐GQDs/NiCo₂S₄ nanoarray grown on carbon cloth as a flexible air cathode exhibits superior electrocatalytic activities toward both oxygen reduction reaction (ORR) and oxygen evolution reaction (OER), outstanding cycle stability (200 h at 20 mA cm^?2), and excellent mechanical flexibility (without observable decay under various bending angles). These impressive enhancements in electrocatalytic performance are mainly attributed to bifunctional active sites within the N‐GQDs/NiCo₂S₄ catalyst and synergistic coupling effects between N‐GQDs and NiCo₂S₄. Density functional theory analysis further reveals that stronger OOH* dissociation adsorption at the interface between N‐GQDs and NiCo₂S₄ lowers the overpotential of both ORR and OER.     

Conversion Synthesis of Self‐Standing Potassium Zinc Hexacyanoferrate Arrays as Cathodes for High‐Voltage Flexible Aqueous Rechargeable Sodium‐Ion Batteries

Prussian blue analogs exhibit great promise for applications in aqueous rechargeable sodium‐ion batteries (ARSIBs) due to their unique open framework and well‐defined discharge voltage plateau. However, traditional coprecipitation methods cannot prepare self‐standing electrodes to meet the needs of wearable energy storage devices. In this work, a water bath method is reported to grow microcube‐like K₂Zn₃(Fe(CN)₆)₂·9H₂O on carbon cloth (CC) using Zn nanosheet arrays as the zinc source and reducing agent, directly serving as a self‐standing cathode. Benefiting from fast ion diffusion and high conductivity, the cathode delivers a high areal capacity of 0.76 mAh cm^?2 at 0.5 mA cm^?2 and excellent capacity retention of 57.9% as the current density increases to 20 mA cm^?2. By coupling with NaTi₂(PO₄)₃ grown on CC as an anode, a quasi‐solid‐state flexible ARSIB with a high output voltage plateau of 1.6 V is successfully assembled, exhibiting a superior areal capacity of 0.56 mAh cm^?2 and energy density of 0.92 mWh cm^?2. In particular, the device shows admirable mechanical flexibility, maintaining 90.3% of initial capacity after 3000 bending cycles. This work is anticipated to open a new avenue for the rational design of self‐standing electrodes used in high‐voltage flexible ARSIBs.     

High Areal Capacity Li‐Ion Storage of Binder‐Free Metal Vanadate/Carbon Hybrid Anode by Ion‐Exchange Reaction

Storing more energy in a limited device area is very challenging but crucial for the applications of flexible and wearable electronics. Metal vanadates have been regarded as a fascinating group of materials in many areas, especially in lithium‐ion storage. However, there has not been a versatile strategy to synthesize flexible metal vanadate hybrid nanostructures as binder‐free anodes for Li‐ion batteries so far. A convenient and versatile synthesis of M_xV_yO_x+2.5y@carbon cloth (M = Mn, Co, Ni, Cu) composites is proposed here based on a two‐step hydrothermal route. As‐synthesized products demonstrate hierarchical proliferous structure, ranging from nanoparticles (0D), and nanobelts (1D) to a 3D interconnected network. The metal vanadate/carbon hybrid nanostructures exhibit excellent lithium storage capability, with a high areal specific capacity up to 5.9 mAh cm^?2 (which equals to 1676.8 mAh g^?1) at a current density of 200 mA g^?1. Moreover, the nature of good flexibility, mixed valence states, and ultrahigh mass loading density (over 3.5 mg cm^?2) all guarantee their great potential in compact energy storage for future wearable devices and other related applications.     

A Novel Potassium‐Ion‐Based Dual‐Ion Battery

In this work, combining both advantages of potassium‐ion batteries and dual‐ion batteries, a novel potassium‐ion‐based dual‐ion battery (named as K‐DIB) system is developed based on a potassium‐ion electrolyte, using metal foil (Sn, Pb, K, or Na) as anode and expanded graphite as cathode. When using Sn foil as the anode, the K‐DIB presents a high reversible capacity of 66 mAh g^?1 at a current density of 50 mA g^?1 over the voltage window of 3.0–5.0 V, and exhibits excellent long‐term cycling performance with 93% capacity retention for 300 cycles. Moreover, as the Sn foil simultaneously acts as the anode material and the current collector, dead load and dead volume of the battery can be greatly reduced, thus the energy density of the K‐DIB is further improved. It delivers a high energy density of 155 Wh kg^?1 at a power density of 116 W kg^?1, which is comparable with commercial lithium‐ion batteries. Thus, with the advantages of environmentally friendly, cost effective, and high energy density, this K‐DIB shows attractive potential for future energy storage application.     

A TiN Nanorod Array 3D Hierarchical Composite Electrode for Ultrahigh‐Power‐Density Bromine‐Based Flow Batteries

Bromine‐based flow batteries are well suited for stationary energy storage due to attractive features of high energy density and low cost. However, the bromine‐based flow battery suffers from low power density and large materials consumption due to the relatively high polarization of the Br₂/Br^? couple on the electrodes. Herein, a self‐supporting 3D hierarchical composite electrode based on a TiN nanorod array is designed to improve the activity of the Br₂/Br^? couple and increase the power density of the bromine‐based flow battery. In this design, a carbon felt provides a composite electrode with a 3D electron conductive framework to guarantee high electronic conductivity, while the TiN nanorods possess excellent catalytic activity for the Br₂/Br^? electrochemical reaction to reduce the electrochemical polarization. Moreover, the 3D micro–nano hierarchical nanorod‐array alignment structure contributes to a high electrolyte penetration and a high ion‐transfer rate to reduce diffusion polarization. As a result, a zinc–bromine flow battery with the designed composite electrode can be operated at a current density of up to 160 mA cm^?2, which is the highest current density ever reported. These results exhibit a promising strategy to fabricate electrodes for ultrahigh‐power‐density bromine‐based flow batteries and accelerate the development of bromine‐based flow batteries.     

The Regulating Role of Carbon Nanotubes and Graphene in Lithium‐Ion and Lithium–Sulfur Batteries

The ever‐increasing demands for batteries with high energy densities to power the portable electronics with increased power consumption and to advance vehicle electrification and grid energy storage have propelled lithium battery technology to a position of tremendous importance. Carbon nanotubes (CNTs) and graphene, known with many appealing properties, are investigated intensely for improving the performance of lithium‐ion (Li‐ion) and lithium–sulfur (Li–S) batteries. However, a general and objective understanding of their actual role in Li‐ion and Li–S batteries is lacking. It is recognized that CNTs and graphene are not appropriate active lithium storage materials, but are more like a regulator: they do not electrochemically react with lithium ions and electrons, but serve to regulate the lithium storage behavior of a specific electroactive material and increase the range of applications of a lithium battery. First, metrics for the evaluation of lithium batteries are discussed, based on which the regulating role of CNTs and graphene in Li‐ion and Li–S batteries is comprehensively considered from fundamental electrochemical reactions to electrode structure and integral cell design. Finally, perspectives on how CNTs and graphene can further contribute to the development of lithium batteries are presented.     

Recent Development in Separators for High‐Temperature Lithium‐Ion Batteries

Lithium‐ion batteries (LIBs) are promising energy storage devices for integrating renewable resources and high power applications, owing to their high energy density, light weight, high flexibility, slow self‐discharge rate, high rate charging capability, and long battery life. LIBs work efficiently at ambient temperatures, however, at high‐temperatures, they cause serious issues due to the thermal fluctuation inside batteries during operation. The separator is a key component of batteries and is crucial for the sustainability of LIBs at high‐temperatures. The high thermal stability with minimum thermal shrinkage and robust mechanical strength are the prime requirements along with high porosity, ionic conductivity, and electrolyte uptake for highly efficient high‐temperature LIBs. This Review deals with the recent studies and developments in separator technologies for high‐temperature LIBs with respect to their structural layered formation. The recent progress in monolayer and multilayer separators along with the developed preparation methodologies is discussed in detail. Future challenges and directions toward the advancement in separator technology are also discussed for achieving remarkable performance of separators in a high‐temperature environment.