High Energy Storage Devices Research Articles

Antiferroelectric Lead based Perovskite Material properties andapplications: A Review

In this review paper, the discussion is about some of the lead based antiferroelectric (AFE) perovskite materials. The antiferroelectric perovskite materials mainly lead zirconate (PZ) and lead zirconate titanate (PZT) prepared by solid state reaction route with their structure change at different concentrations, phase transition, their dielectric properties ormore. These materials caught the attention of the researchers because of their use in high energy storage devices, pyroelectric devices, sensors, cooling devices, pulse power generators and have many more applications. The reason could be their electric field phase transformation between the antiferroelectric (AFE) state and ferroelectric (FE) state and the phase switching property can be one of the strong factors responsible for the performance of the PZ based materials. Thecentral focus of this review is to briefly explain the continuous increase in research in the antiferroelectric materials by enhancing the PZ with many dopants. We mainly address PZ and PZT solid solution properties.

Investigating the influence of Cu and Ti substitution on the structural, optical, and dielectric properties of BiFeO3.

The environmentally friendly BiFe1-x(Ti1/2Cu1/2)xO3 system with various substitution rates, including x = 0 (BFO), x = 0.02 (BFTCO2) and x = 0.04 (BFTCO4), has been synthesized using the solid-state reaction technique. All compositions exhibited a distorted rhombohedral structure with R3c space, as observed from the results of XRD and Raman spectroscopy. A significant impurity phase (Bi25FeO40) appears in pure and doped BFO, with a percentage ranging between 6 and 9%. This impurity was also detected using Mössbauer spectroscopy. UV-vis spectroscopy revealed a decrease in optical band energy with the substitution, suggesting the potential applications of doped BFO within the visible range of the spectrum, making it suitable for photocatalytic and solar cell applications. The smallest bandgap was observed for BFTCO2 with Eg = 1.93 eV. The origin of this reduction is discussed from a scientific point of view. Furthermore, Cu2+ and Ti4+ co-doped BFO display an improvement in dielectric properties due to the reduction in the value of tan δ. Dielectric measurements revealed an anomaly below TN with diffusive and dispersive behavior, suggesting a relaxor-like behavior for all compositions. The relaxor character was quantified by using the Vogel-Fulcher relationship which yielded activation energy of 0.359-0.614 eV. In our system, the relaxor behavior showed an enhancement with the heterogeneity created by the substitution rate, reaching its maximum for BFTCO4, characterized by the empirical parameters which are: ΔTrelax = 96 K and γ = 1.96. Finally, co-doped BFO ceramics not only present promising materials for optical applications due to the narrow bandgap, but their relaxor behavior can also be tailored for promising applications in high-energy storage devices.

Binderless Sheet-Type Oxide-Sulfide Composite Solid Electrolyte for All-Solid-State Batteries

Lithium-ion batteries have been used as energy sources not only for small electronic devices but also for high-capacity and high-energy-density applications such as electric vehicles. However, the use of flammable organic liquid electrolytes in lithium-ion batteries has raised safety concerns in various applications. Therefore, solid-state batteries using flame-retardant inorganic materials are considered a more reasonable direction for future energy sources due to their high safety and high energy density. Solid electrolytes(SEs) are divided into oxide-based, sulfide-based, and polymer-based. Each solid electrolyte has its own advantages and disadvantages. Oxide-based solid electrolytes (e.g., Li7La3Zr2O12 (LLZO), Li3xLa2/3-xTiO3 (LLTO), Li1.3Al0.3Ti1.7(PO4)3 (LATP)) are air-stable and exhibit excellent electrochemical properties over a wide potential range. However, their high interfacial resistance may limit their practical application as batteries. Sulfide-based solid electrolytes (e.g., Li6PS5X (X=Cl, Br, I), Li10GeP2S12, (100-x)Li2S-xP2S5)) have high ionic conductivity, ductile properties, low interfacial resistance, and good room temperature workability. However, they are vulnerable to atmospheric instability, which can produce toxic gases such as H2S, and are relatively electrochemically unstable with Li metal. Polymer-based solid electrolytes, such as those made from polymers like PEO, PVDF, PAN, etc. that are compounded with other solid electrolytes (oxides, sulfides, etc.), offer the advantage of being able to form solid electrolyte membranes over large areas. But they have low ionic conductivity and weak mechanical properties of the polymer itself, limiting their practical application. To apply solid-state batteries to practical high-energy density energy storage devices such as electric vehicles, high ion conductivity, electrochemical stability, high mechanical properties, and large area formation of the electrolyte layer are essential. Solid electrolytes are mainly formed in powder form, and without a polymer binder, it is limited to apply as a film for large-capacity storage devices. Here, we fabricated a freestanding sheet-type Al-LLZO oxide-based solid electrolyte that forms a 3D network without a polymer material using an electrospinning method. In addition, we prepared a oxide-sulfide composite solid electrolyte membrane by impregnating LPSCl sulfide-based solid electrolyte into the Al-LLZO solid electrolyte sheet. As a result, This process removed the polymer and improved both the ionic conductivity and mechanical properties. Furthermore, it was possible to achieve both large-area and film characteristics without the need for a polymer.

Highly stable and thin layer of conducting PANI decorative on porous 3D nanoflakes like-NiCo2O4/CF nanomaterials for efficient Hybrid Supercapacitors application

A systemically planned three-step procedure for producing conducting polymers (CP) layer coated on porous nanoflakes like NiCo2O4 improves electrochemical supercapacitor applications. i) In the first step, deep eutectic solvent (DES) has been employed as a solvent to synthesize an interconnected NiCo2O4 nanoflakes, ii) second step includes the hydrothermally synthesized polyaniline (PANI) decorated on NiCo2O4 nanoflakes, and iii) in third step, cellulose nanofiber (CF) powder has been added in the optimum NiCo2O4/PANI sample in order to improve the electrochemical activity. The surface morphology systematically modified as nanoflowers, nanocubes, and nanoflakes with respect to the products such as Ni(OH)2, Co3O4 and NiCo2O4, respectively. 0.2 mg PANI/NiCo2O4/CF electrode is found to be a suitable hybrid combination with an excellent electrode performance with a specific capacity (Cs) of 369 mAh g−1 and improved electrochemical conductivity. The NCO/PANI/CF//AC asymmetric device has been fabricated which further resulted into the widen potential window (1.5 V), larger Cs values (406 F g−1), and greater energy (60.60 W h kg−1) and power densities (2322 W kg−1). Thus, NiCo2O4 decorated with PANI and CF composed nanohybrid material is an ideal electrode for high performance electrochemical energy storage devices.

Solvent-Free Ultrafast Construction of Se-Deficient Heterojunctions of Bimetallic Selenides toward Flexible Sodium-Ion Full Batteries.

Flexible quasi-solid-state sodium ion batteries featuring their low-cost, high safety and excellent mechanical strength have attracted widespread interest in the field of wearable electronic devices. However, the development of such batteries faces great challenges including the construction of interfacial compatible flexible electrode materials and addressing the high safety demands of electrolyte. Here selenium-vacancies regulated bimetallic selenide heterojunctions anchored on waste cotton cloth-derived flexible carbon cloth (FCC) with robust interfacial C-Se-Co/Fe chemical bonds as a flexible anode material (CCFSF) is proposed by ultrafast microwave pyrolysis method. Rich selenium vacancies and CoSe2 /FeSe2-x heterostructures are synchronously formed that can significantly improve ionic and electronic diffusion kinetics. Additionally, a uniform carbon layer coating on the surface of Se-deficient heterostructures endows it with outstanding structural stability. The flexible cathode (PB@FCC) is also fabricated by directly growing Prussian blue nanoparticles on the FCC. Furthermore, an advanced flexible quasi-solid-state Na-ion pouch cell is assembled by coupling CCFSF anode, PB@FCC cathode with P(VDF-HFP)-based gel polymer electrolyte. The full cell not only demonstrates excellent energy storage performance but also robust mechanical flexibility and safety. The present work offers an effective avenue to achieve high safety flexible energy storage device, promoting the development of flexible wearable electronic devices.

Optimizing energy storage density of the multi–layer composite of poly(vinylidene fluoride) and nano–Ni plated CaCu3Ti4O12 with an ultralow filling content

Surface modification of nanoceramics with high dielectric constant can increase dielectric constant of polymer composites voiding excessive dielectric loss, however, low discharged energy density (Ud) of composites at a low loading limits potential applications in high–energy–storage devices under low electric field. Herein, Ni–plated CaCu3Ti4O12 nanoparticle (CCTO@Ni) is used to improve the electric properties of the poly(vinylidene fluoride) monolayer composites (C/PVDF), and an ultralow loading of 0.5 vol% promotes the largest Ud of 2.53 J/cm3 at 230 MV/m, resulting from MWS interface polarization and Coulomb barrier effect included by CCTO@Ni fillers, which is used to further prepare three kinds of multi–layer structured C/PVDF composites by solution casting layer by layer. Comprehensive testing shows that the PVDF–C/PVDF–PVDF–C/PVDF–PVDF five–layer film (P–C–P–C–P) enhances the dielectric constant and breakdown strength to contribute the maximal Ud of 6.65 J/cm3 at 297.8 MV/m, which is 118% larger than that of pure PVDF. Above excellent characteristics are attributed to the interface polarization of the middle C/PVDF layer and the alleviating and blocking effect of the middle and outer PVDF layers, which are clarified in depth by the finite element simulation and enhanced breakdown model.

Structural regulation enabled stable hollow molybdenum diselenide nanosheet anode for ultrahigh energy density sodium ion pouch cell

For the continued use of sodium-ion batteries (SIBs), which require matching anode materials, it is crucial to create high energy density energy storage devices. Here, hollow nanoboxes shaped carbon supported sulfur-doped MoSe2 nanosheets (S-MoSe2@NC) are fabricated by in situ growth and heterodoping strategy. This ensures that the MoSe2 nanosheets are tightly anchored to the nanoboxes carbon, and the structure can effectively buffer the volume stress caused by sodium ion (de)intercalation, as well as providing abundant ion/electron migration transportations. As anode for SIBs, the S-MoSe2@NC shows a higher rate capability and excellent cycling stability (431.1 mAh/g after 1100 cycles at 10 A/g). This excellent cycle life and high rate ability are due to the structural stability and outstanding electronic conductance with reduced band gap of the S-MoSe2@NC, as evidenced by the diffusion analysis and theoretical calculation. In order to promote the application of SIBs, the S-MoSe2@NC and NaNi1/3Fe1/3Mn1/3O2 were assembled into a pouch cell, and the test found that besides the excellent cycle rate performance, the ultrahigh energy density of 256 Wh kg−1 and flexible characteristics can be achieved. This study has proven that building a structure with a rock-steady foundation and quick ion migration may efficiently control sodium storage and pave the way for novel applications of high-performance transition metal dichalcogenides in sodium storage.

Converting LiNO3 additive to single nitrogenous component Li2N2O2 SEI layer on Li metal anode in carbonate-based electrolyte

With the increasing demand for high energy density energy storage device, Li metal has received intensive attention for its ultrahigh capacity and the lowest redox potential. LiNO3 is widely used as electrolyte additive for ether electrolyte, which can improve the cycle performance of Li metal anode. Compared to ethers, carbonates are more suitable for Li metal batteries with high voltage cathode because they have a wider electrochemical window. However, LiNO3 performs poor solubility in carbonate electrolyte, restricting its application in high voltage Li battery. Herein, we presented a facile method to introduce abundant LiNO3 additive to carbonate electrolyte system by introducing LiNO3-PAN es as the interlayer of the cell. LiNO3-PAN es is in sufficient contact with the electrolyte so that it can continuously releases LiNO3 to assist the formation of Li2N2O2-rich single nitrogenous component SEI layer on Li surface. With the help of LiNO3-PAN es, Li metal anode shows excellent cycle stability even at a high current density of 4 mA/cm2, so that the cycle performance of the full cells was significantly improved, whether in the anode-free Cu||LFP cell or the Li||NCM622 cell.

Reducing interfacial thermal resistance between polyethylene oxide-based solid-state polymer electrolyte and lithium anode by using IVA group two-dimensional materials: A molecular dynamics study

Solid-state lithium-ion batteries, as a new generation of high energy density electrochemical energy storage devices, need to meet more stringent thermal management standards. In this work, the interfacial thermal transport phenomena between a polyethylene oxide based solid electrolyte and a lithium anode in solid-state lithium-ion batteries was investigated by using a non-equilibrium molecular dynamics simulation method. To reveal the internal heat transport mechanism of the batteries at the microscopic level and to enhance the heat dissipation in them, IVA group two-dimensional monolayer materials such as graphene, silicene, and germanene were inserted at the interface and the interfacial thermal resistances were calculated to compared with the pristine interface. It was found that interfacial interactions were enhanced and the lattice vibrations were coupled by inserting the monolayer materials. Also, compared to the pristine interface, the interfacial thermal resistance was reduced by 83.89 %, 76.05 % and 55.99 %, respectively. Thus, this work provides valuable insights into the thermal transport between electrodes and electrolytes in solid-state lithium-ion batteries, and provides methodological references for improving the heat dissipation and thermal management efficiency inside the batteries.

Enhancing pseudocapacitive intercalation in Ti3C2T x MXene with molecular crowding electrolytes

The growing demand for safe, cost-efficient, high-energy and high-power electrochemical energy storage devices has stimulated the development of aqueous-based supercapacitors with high capacitance, high rate capability, and high voltage. 2D titanium carbide MXene-based electrodes have shown excellent rate capability in various dilute aqueous electrolytes, yet their potential window is usually narrower than 1.2 V. In this study, we show that the potential window of Ti3C2T x MXene can be efficiently widened to 1.5 V in a cost-effective and environmentally benign polyethylene glycol (PEG) containing molecular crowding electrolyte. Additionally, a pair of redox peaks at −0.25 V/−0.05 V vs. Ag (cathodic/anodic) emerged in cyclic voltammetry after the addition of PEG, yielding an additional 25% capacitance. Interestingly, we observed the co-insertion of the molecular crowding agent PEG-400 during the Li+ intercalation process based on in-situ x-ray diffraction analysis. As a result, Ti3C2T x electrodes presented an interlayer space change of 4.7 Å during a complete charge/discharge cycle, which is the largest reversible interlayer space change reported so far for MXene-based electrodes. This work demonstrates the potential of adding molecular crowding agents to improve the performance of MXene electrodes in aqueous electrolytes and to enlarge the change of the interlayer spacing.

High-Performance K Metal Batteries Enabled by Regulating an Electrolyte Solvation Structure

Batteries using a potassium metal (K-metal) anode are attention to a new type of low-cost and high-energy storage devices. However, the thermodynamic instability of the K-metal anode in organic electrolyte solutions causes uncontrolled growth of dendrites and parasitic reactions, which leads rapid capacity loss and low Coulombic efficiency.[1-4] In this presentation, I will introduce the advanced electrolyte using dual-salt for regulated solvation chemistry showing an improved the K-metal anode stability. Experimental and theoretical studies supported the details of solvation chemistry and results. Incorporating dual-salt into the electrolyte solution decreased the number of free solvent molecules surrounding the K+ leading to facile K+ desolvation as well as lowering the exchange current density improving the uniform K electrodeposition. Moreover, the modified electrolyte mitigates decomposition of the solvent molecules and leads to form enhanced mechanical rigidity of the SEI layer on the surface of the K–metal electrode with larger fraction of KF compound. Compared to previous studies, the K-metal anode using modified electrolyte shows long cycling stability at fast charge-discharge capability in symmetrical K | K cells. Even under high current density, the modified electrolyte ensures high areal capacity and an unprecedented lifespan with stable Coulombic efficiency for the K-metal full battery employing a sulfurized polyacrylonitrile cathode. M. Park, Y. Jeong, M. H. Alfaruqi, Y. Liu, X. Xu, S. Xiong, M.–G. Jung, H.–G. Jung, J. Kim, J.–Y. Hwang, Y.–K. Sun. Stable Solid Electrolyte Interphase for Long–Life Potassium Metal Batteries, ACS Energy Lett. 7 (2022) 401–409.Kim, W. Song, D.–Y. Son, L. K. One, Y. Qi. Lithium–Ion Batteries: Outlook on Present, Future, and Hybridized Technologies. J. Mater. Chem. A 7 (2019) 2942–2964.–H. Kim, G.–T. Park, B.–K. Son, G. W. Nam, J. Liu, L.–Y. Kuo, P. Kaghazchi, C. S. Yoon, Y.–K. Sun. Heuristic Solution for Achieving Long–Term Cycle Stability for Ni–Rich Layered Cathodes at Full Depth of Discharge, Nat. Energy 5 (2020) 860.–Y. Hwang, S.–T. Myung, Y.–K. Sun. Recent Progress in Rechargeable Potassim Batteries, Adv. Funct. Mater. 28 (2018) 1802938.

(Invited) Rapid, Large Area Preparation of Few-Layer Graphene Films Using Xenon Flash Lamp Pyrolysis for High-Performance Structural Micro-Supercapacitors

Graphene offers excellent electrical conductivity and very high surface area, which holds great promise for energy storage applications including supercapacitors. Current preparation methods for graphene require relatively long processing times, extremely high temperatures within controlled atmospheres, and/or involve multi-step reactions that present challenges for high throughput fabrication of graphene-based energy storage devices. We report a novel photothermal route to large-scale production of graphene within milliseconds using a commercially available polymers (polybenzoxazine, polyacrylonitrile and polyaniline) and a high intensity xenon flash lamp on various substrates, including carbon fibers, at ambient conditions. The xenon flash lamp provides large-area illumination and a wide emission band (300 nm –1100 nm) that was used to convert the polymeric material directly into few layer graphene upon millisecond exposures. The precursor material is heated to extremely high temperatures in a fraction of a second – a duration that is much shorter than the timescale for thermal equilibrium. This enabled the conversion of the polymeric material into few layer graphene in air and at room temperature, and without thermally damaging the substrate. Conversion to few-layer graphene was strongly dependent on pulse energy and the local temperature which was controlled via pulse power modulation. The obtained graphene composites at optimized conditions exhibited excellent conductivity (0.1 ohm-cm) with ID/IG ratio of 0.3 (Figure 1a). Particularly, graphene derived from polyaniline resulted in the formation of macroporous network (Figure 1b) with good adhesion to the carbon fiber, all of which facilitate the transport of ions through the material. The fabricated supercapacitor devices exhibited a very high areal capacitance of 200 mF/cm2 at 10 mV/s with retention of more than 70% of their capacitance, even at scan rates up to 100 mV/s. Moreover, mechanically, and structurally stable graphene derived from polyaniline on carbon fiber was utilized for the preparation of structural energy storage devices. We assembled symmetric structural supercapacitor comprised of carbonaceous material (carbon fiber and few-layer graphene) and polymer gel electrolyte. This resulted in the preparation of large area device (40 cm2) as shown in the Figure 1c with the capacitance exceeding 2000 mF and almost complete retention of capacitance after 5000 cycles.The preparation of high-quality graphene via photothermal pyrolysis of polymer is amenable to high throughput processing, enabling large-scale production of high performance structural electrochemical energy storage devices. Figure 1

A La2O3/MXene composite electrode for supercapacitors with improved capacitance and cycling performance

ABSTRACT Developing efficient electrode materials is a key towards high power electrochemical energy storage devices. Two-dimensional (2D) MXene shows excellent conductivity and electrochemical performance among other materials. However, the restacking of MXene layers may degrade their specific capacity and cycling performance. Considering this challenge, here we have designed a composite made of 2D MXene nanosheets and lanthanum oxide (La2O3) nanoparticles to overcome the limitations. The bifunctionality of La2O3 nanoparticles prevents the restacking of MXene layers and enhances the electrochemical properties of the electrode due to its good Faradic characteristics. The specific capacitance of the La2O3/MXene composite electrode is 366 F/g at 1 A/g, which is 4.5 and 3 times higher than those of the individual La2O3 and MXene. The composite electrode displays a capacitance retention of 96% after 1,000 cycles, which is due to synergistic effects between the two components and indicates the potential of La2O3/MXene composite for supercapacitors.

On the Viability of Lithium Bis(fluorosulfonyl)imide as Electrolyte Salt for Use in Lithium‐Ion Capacitors

AbstractLithium‐ion capacitors (LICs) represent promising high‐power energy storage devices, most commonly composed of a lithium‐ion intercalation anode (e. g., graphite or hard carbon), a supercapacitor activated carbon (AC) cathode, and an electrolyte with 1 M LiPF6 in carbonate solvents. LiPF6 is susceptible to hydrolysis, forming HF, which leads to challenges for disassembly and recycling, risks during hazardous events, and extensive energy consumption during production. Here, we report on the feasibility of replacing LiPF6 with the non‐hydrolysing salt LiFSI for use with AC electrodes. Based on voltage hold measurements in a half‐cell setup, good long‐term stability is achieved with an upper cut‐off voltage of 3.95 V vs. Li/Li+, potentially enabling cell voltages of ~3.8 V when combined with graphite or silicon‐based anodes (operating at ~0.1 V vs. Li/Li+) in LIC full cells. The lower cut‐off voltage was determined to be 2.15 V vs. Li/Li+. The systematic comparison of CV, leakage current analysis and capacity retention upon voltage hold highlights the importance of the latter method to provide a realistic assessment of the electrochemical stability window (ESW) of LiFSI on a commercial AC electrode. The morphological and surface‐chemical post‐mortem analysis of AC electrodes used with LiFSI revealed that the oxidation of the FSI anion, as evidenced by the presence of new S 2p and N 1s features in the XPS spectra, and an increasing number of oxygenated species on the AC were the main processes causing capacity fade at positive polarization.

Synergistic effect and enhanced safety of double dynamic solid polymer electrolytes for lithium metal batteries

A solid polymer electrolyte with low mechanical strength and poor flexibility will cause mechanical degradation, short circuits, or functional failures in lithium ion batteries (LIBs). Therefore, introducing an double dynamic solid polymer electrolytes with high ionic conductivity, good mechanical strength, and excellent self-healing ability for stabilizing the solid electrolyte interface, preventing battery fire, and suppressing Li dendrite growth will further improve the reliability, security, and lifetime of the LIBs. Herein, a series of dual dynamic self-healing solid polymer electrolytes (DD-shSPEs) are developed via the Schiff base reaction between different molar ratios of polyethylene glycol derivative (tat-PEG) and terephthalaldehyde. The hydrogen bond and the highly reversible imine bonds endow DD-shSPEs with rapid self-repairing capacity to cure mechanical damage within 5 min at normal temperature. The self-healing polymer electrolytes also exhibit excellent stretchability, which can satisfy the external deformation of the battery. Meanwhile, after self-healing, the ionic conductivities of the electrolytes can hold the original values. Also, the initial discharge capacity (IDC) of the battery based on DD-shSPEs reach to 149.3 mAh g-1 under a current rate of 0.1 C, and still maintains 144.2 mAh g−1 after 100 cycles. Besides, the polymer electrolyte (PE) also exhibits good interfacial stability and have a cycle life of more than 650 h at a current density of 0.2 mA cm-2. Accordingly, this work shows that the high-performance PE based on self-healing materials is promising for constructing high stable solid-state energy storage device.

Microenvironment engineering for guiding spatially and epitaxially uniform lithium plating in lithium metal batteries

The manipulation of plated lithium morphology is the crucial for extending the cycle life of lithium metal batteries. Dendritic growth, a major concern, is influenced by the microenvironment of lithium plating, including the curvature of lithium-ion transfer path, as well as the inner space and surface chemistry of the separator and scaffold. In this study, we report a novel separator-interface-scaffold microenvironment for practical lithium metal batteries (LMBs), in which surface chemistry of scaffold and separator are tuned to create a transmission path with low curvature and induce spatially and epitaxial lithium plating. With such an elaborate design, the resulting LMB demonstrates exceptional stability, exhibiting dendrite-free cycling for 5542 h with a low voltage hysteresis of 13 mV at 5 mA cm−2/5 mAh cm−2. It also demonstrates stable cycling for 500 h under ultrahigh currents of 50 mA cm−2 and deep plating/stripping up to 20 mAh cm−2. Notably, a remarkable cumulative plating capacity of 13,855 mAh cm−2 is achieved. The full cells paired with commercial cathodes with high loading mass delivered remarkably improved rate and cycling stability performance. This study highlights the critical role of the plating microenvironment in enhancing LMBs for high-energy storage devices.

Crystal transformation engineering for effective polysulfides blocking layer for excellent energy density lithium–sulfur batteries

Lithium–sulfur batteries (LSBs) with ultra-high energy density are emerging as the best alternative for next-generation energy storage systems. Nevertheless, polysulfide (LiPS) shuttling induces rapid capacity diminution, and short battery lifespan, which seriously hinders their practical application. Herein, a solvothermal and controlled pyrolysis process was used to synthesize the metal-organic frameworks derived m–/c–ZrO2 heterojunction distributed on nitrogen-doped porous carbon (NC) and uniformly wrapped by graphene sheets. Electrochemical investigation demonstrates that the m–/c–ZrO2/NCG heterostructure modified separator can efficiently impede LiPSs shuttling and regulate the conversion reaction of long-chain LiPSs, which is further confirmed by first-principles theoretical calculations. The as-prepared m–/c–ZrO2/NCG-based LSBs showed remarkable cyclability with a decay rate of 0.023 % per cycle over 1000 cycles at a high rate of 2 C. Importantly, at very high sulfur loading of 6.8 mg cm−2, an excellent reversible specific capacity of 924.1 mAh g−1 at 0.2 C after 100 cycles is achieved, which is expected to obtain high energy performance. This work delivers a promised strategy for the rational design of multifunctional heterostructure for stable and safe LSBs, providing a means of narrowing the gap for the commercialization of high-energy next-generation electrochemical storage devices.

Polymer-Grafted Nanoparticles with Variable Grafting Densities for High Energy Density Polymeric Nanocomposite Dielectric Capacitors.

Designing high energy density dielectric capacitors for advanced energy storage systems needs nanocomposite-based dielectric materials, which can utilize the properties of both inorganic and polymeric materials. Polymer-grafted nanoparticle (PGNP)-based nanocomposites alleviate the problems of poor nanocomposite properties by providing synergistic control over nanoparticle and polymer properties. Here, we synthesize "core-shell" barium titanate-poly(methyl methacrylate) (BaTiO3-PMMA) grafted PGNPs using surface-initiated atom transfer polymerization (SI-ATRP) with variable grafting densities of (0.303 to 0.929) chains/nm2 and high molecular masses (97700 g/mL to 130000 g/mol) and observe that low grafted density and high molecular mass based PGNP show high permittivity, high dielectric strength, and hence higher energy densities (≈ 5.2 J/cm3) as compared to the higher grafted density PGNPs, presumably due to their "star-polymer"-like conformations with higher chain-end densities that are known to enhance breakdown. Nonetheless, these energy densities are an order of magnitude higher than their nanocomposite blend counterparts. We expect that these PGNPs can be readily used as commercial dielectric capacitors, and these findings can serve as guiding principles for developing tunable high energy density energy storage devices using PGNP systems.

Regulating the Solvation Structure of Electrolyte via Dual–Salt Combination for Stable Potassium Metal Batteries

Batteries using potassium metal (K-metal) anode are considered a new type of low-cost and high-energy storage device. However, the thermodynamic instability of the K-metal anode in organic electrolyte solutions causes uncontrolled dendritic growth and parasitic reactions, leading to rapid capacity loss and low Coulombic efficiency of K-metal batteries. Herein, an advanced electrolyte comprising 1M potassium bis(fluorosulfonyl)imide (KFSI) + 0.05M potassium hexafluorophosphate (KPF6 ) dissolved in dimethoxyethane (DME) is introduced as a simple and effective strategy of regulated solvation chemistry, showing an enhanced interfacial stability of the K-metal anode. Incorporating 0.05M KPF6 into the 1M KFSI in DME electrolyte solution decreases the number of solvent molecules surrounding the K ion and simultaneously leads to facile K+ de-solvation. During the electrodeposition process, these unique features can lower the exchange current density between the electrolyte and K-metal anode, thereby improving the uniformity of K electrodeposition, as well as potentially suppressing dendritic growth. Even under a high current density of 4mA cm-2 , the K-metal anode in 0.05M KPF6 -containing electrolyte ensures high areal capacity and an unprecedented lifespan with stable Coulombic efficiency in both symmetrical half-cells and full-cells employing a sulfurized polyacrylonitrile cathode.

3D‐Printed Graded Electrode with Ultrahigh MnO2 Loading for Non‐Aqueous Electrochemical Energy Storage

AbstractElectrolytic manganese dioxide is one of the promising cathode candidates for electrochemical energy storage devices due to its high redox capacity and ease of synthesis. Yet, high‐loading MnO2 often suffers from sluggish reaction kinetics, especially in non‐aqueous electrolytes. The non‐uniform deposition of MnO2 on a porous current collectors also makes it difficult to fully utilize the active materials at high mass loading. Here, a 3D printed graded graphene aerogel (3D GA) that contains sparsely separated exterior ligaments is developed to create large open channels for mass transport as well as densely arranged interior ligaments providing large ion‐accessible active surface. The unique structural design homogenizes the thickness of electro deposited MnO2 even at an ultrahigh mass loading of ≈70 mg cm−2. The electrode achieves a remarkable volumetric capacity of 29.1 mA h cm−3 in the non‐aqueous electrolyte. A Li‐ion hybrid capacitor device assembled with a graded 3D GA/MnO2 cathode and graded 3D GA/VOx anode exhibits a wide voltage window of 0–4 V and a superior volumetric energy density of 20.2 W h L−1. The findings offer guidance on 3D printed electrode design for supporting ultrahigh loading of active materials and developments of high energy density energy storage devices.