Safe Energy Storage Research Articles

Coordination in islanded microgrids: Integration of distributed generation, energy storage system, and load shedding using a new decentralized control architecture

For an islanded microgrid (MG) to work reliably, it is essential to manage the control of distributed energy resources, including generation and storage units, as well as loads, in a coordinated manner. In islanded microgrids, the safe energy storage limits must be accounted for coordination to avoid rapid damage or degradation to the storage units. In this paper, a novel control method is introduced to coordinate distributed generation (DG) and energy storage systems (ESS) in an islanded MG to enhance penetration and complete exploitation of DGs and ESSs and maintain balanced state of charge (SoC). A decentralized modified droop function (MDF) is suggested to share power and to control voltage and frequency without communication link. This controller uses virtual impedance to separate active and reactive power in the primary level control loop. Moreover, based on the ESS's charge state and its control as a frequency control support system, the proposed controller enables DGs to operate in both voltage and frequency control mode (VFCM) and active power control mode (APCM) to avoid overcharging. Likewise, to prevent from over discharging and maintain the frequency within permissible range, a new load shedding strategy is implemented to minimize the cycles of load connection and disconnection. The validation and effectiveness of the proposed control system are demonstrated by simulation results.

Proton Hydrogel-Based Supercapacitors with Rapid Low-Temperature Self-Healing Properties.

Hydrogel-based supercapacitors are an up-and-coming candidate for safe and portable energy storage. However, it is challenging for hydrogel electrolytes to achieve high conductivity and rapid self-healing at subzero temperatures because the movements of polymer chains and the reconstruction capability of broken dynamic bonds are limited. Herein, a highly conductive proton polyacrylamide-phytic acid (PAAm-PA) hydrogel electrolyte with rapid and autonomous self-healing ability and excellent adhesion over a wide temperature range is developed. PA, as a proton donor center, endows the hydrogels with high conductivity (102.0 mS cm-1) based on the Grotthuss mechanism. PA can also prevent the crystallization of water and form multiple reversible hydrogen bonds in the polymer network, which solves the dysfunction of self-healing hydrogels in a cryogenic environment. Accordingly, the hydrogel electrolytes demonstrate fast low-temperature self-healing ability with a self-healing efficiency of 79.4% within 3 h at -20 °C. In addition, the hydrogel electrolytes present outstanding adhesiveness on electrodes due to the generation of hydrogen bonds between PA and activated carbon electrodes. As a result, the integrated hydrogel-based supercapacitors with tight bonding electrode/electrolyte interface deliver a 139.5 mF cm-2 specific capacitance at 25 °C. Moreover, the supercapacitors display superb self-healing ability, achieving 92.1% of capacitance recovery after three cutting-healing cycles at -20 °C. Furthermore, the supercapacitors demonstrate only 6.4% capacitance degradation after 5000 charging-discharging cycles at -20 °C. This work provides a roadmap for designing all-in-one flexible energy storage devices with excellent self-healing ability over a wide temperature range.

Oxygenated carbon nitride‐based high‐energy‐density lithium‐metal batteries

AbstractLithium (Li)‐metal batteries with polymer electrolytes are promising for high‐energy‐density and safe energy storage applications. However, current polymer electrolytes suffer either low ionic conductivity or inadequate ability to suppress Li dendrite growth at high current densities. This study addresses both issues by incorporating two‐dimensional oxygenated carbon nitride (2D OCN) into a polyvinylidene fluoride (PVDF)‐based composite polymer electrolyte and modifying the Li anode with OCN. The OCN nanosheets incorporated PVDF electrolyte exhibits a high ionic conductivity (1.6 × 10−4 S cm−1 at 25°C) and Li+ transference number (0.62), wide electrochemical window (5.3), and excellent fire resistance. Furthermore, the OCN‐modified Li anode in situ generates a protective layer of Li3N during cycling, preventing undesirable reactions with PVDF electrolyte and effectively suppressing Li dendrite growth. Symmetric cells using the upgraded PVDF polymer electrolyte and modified Li anode demonstrate long cycling stability over 2500 h at 0.1 mA cm−2. Full cells with a high‐voltage LiNi0.8Co0.1Mn0.1O2 cathode exhibit high energy density and long‐term cycling stability, even at a high loading of 8.2 mg cm−2. Incorporating 2D OCN nanosheets into the PVDF‐based electrolyte and Li‐metal anode provides an effective strategy for achieving safe and high‐energy‐density Li‐metal batteries.

High-performance zinc-ion hydrogel electrolytes based on molecular-level hybridization of PVA with polymer quantum dots

Aqueous zinc ion batteries have received widespread attention. However, the growth of zinc dendrites and hydrogen evolution reaction generation seriously hinder the practical application of zinc ion batteries. Herein, it is reported that a multifunctional dendrites-free low-temperature PVA-based gel electrolyte by introducing negatively charged polymer carbon quantum dots (QDs) and the organic antifreeze dimethyl sulfoxide (DMSO) into it. The QDs carrying a large number of functional groups on the surface can effectively adsorb Zn2+, eliminating the “tip effect”, and inducing the uniform deposition of Zn2+ and the formation of a dendrites-free structure. Meanwhile, the solvation structure of adsorbed Zn2+ can be controlled by charged groups to reduce the generation of side reactions, thus obtaining high-performance zinc ion batteries. The Zn/polyaniline (PANi) full battery can be stably cycled more than 1000 times at –20 °C, and the design of this gel electrolyte can provide good feasibility for safe, stable, and flexible energy storage devices.

Highly soluble and crossover-free all-organic redox pair using N-heterocycle-linked TEMPO and two-electron-capable bipyridinium towards high performance aqueous flow batteries

Aqueous organic redox flow batteries (AORFBs) are the brilliant technologies for safe and sustainable stationary energy storage. However, the cross-contamination, limited cell voltage, and inferior cycling stability remain challenges. Herein, the N-heterocycle-substituted TEMPO (TMP-TEMPO) and pyrrolidinium-/ammonium-grafted bipyridinium ([PyrTMAV]Cl4) redox pair with multiple charges are designed for high-performance AORFBs. The whole material preparation is relatively simple and only needs two or three synthetic steps. The TMP-TEMPO and [PyrTMAV]Cl4 show high aqueous solubility of 2.4 M and 1.71 M, respectively, excellent electrochemical reversibility, and fast redox kinetics. Notably, the introduction of multiple charges into the active materials can produce a strong Gibbs-Donnan effect with ion exchange membranes, thus preventing the permeability of molecules through the membrane and avoiding the cross-contamination of active molecules. By using the crossover-free TMP-TEMPO and two-electron [PyrTMAV]Cl4 redox pair, the assembled two-electron AORFBs at an electron concentration of 0.2 M exhibit stable battery performancein environments with O2 contents of both 10 ppm and 100 ppm with a capacity retention of over 99 % per day for hundreds of cycles (268 and 310 cycles), and a high energy efficiency of ∼89 % and Coulombic efficiency of ∼100 %. Furthermore, the AORFB achieves a high capacity of ∼37.4 Ah L−1 at an ultra-high electron concentration of 1.5 M, while maintaining a capacity retention rate of ∼99.7 % over 138 cycles and a theoretical capacity utilization rate of 93 %. The versatile molecular design for TMP-TEMPO and [PyrTMAV]Cl4 can be easily extended to the synthesis of various amino-functionalized TEMPO and asymmetric bipyridinium derivatives.

Non-sacrificial additive regulated electrode–electrolyte interface enables long-life, deeply rechargeable aqueous Zn anodes

Rechargeable aqueous Zn batteries (RAZBs) offer a promising solution for safe and cost-effective energy storage. However, practical applications of this type of battery are hindered by dendrite formation and side reactions, which primarily stem from the unstable Zn electrode–electrolyte interface (EEI). Here, we report 3-(1-pyridinio)-1-propanesulfonate (PPS) as a novel EEI regulator to tackle these critical issues. Theoretical calculations and experimental results reveal that PPS molecules can be preferentially adsorbed on the Zn anode surface and construct a lean-water EEI, which regulates uniform Zn plating/stripping and minimizes interfacial side reactions. As a result, the addition of PPS enables a Zn//Cu asymmetric cell to achieve an ultra-high Coulombic efficiency of 99.88 % and a lifespan of over 4,000 cycles (around half a year), far exceeding that with a conventional electrolyte (99.65 % and 210 cycles). Remarkably, even at 20 mA cm−2 and a high depth of discharge of 70 %, the Zn//Zn battery using the new electrolyte can still maintain an impressive cycling life of over 250 h. More importantly, the implementation of the designed electrolyte in various Zn-based full cells yields exceptional capacity retention and lifespan. This work underscores the importance of EEI regulation in advancing RAZB technology and offers a simple yet effective strategy for enhancing the stability and reversibility of Zn anodes, which represents a key step toward realizing the full potential of RAZBs for next-generation energy storage.

Deeply Discharged, Quiescently Stable, and Long-Life Zn Anode by Spontaneous SEI Formation.

Zn ion batteries (ZIBs) are a promising candidate in safe and low-cost large-scale energy storage applications. However, significantly deteriorated cycling stability of Zn anode in high depth of charge or after long-term quiescence impedes the practical application of ZIBs. Aiming at the above issue, a spontaneous solid electrolyte interphase (SEI) formation of Zn4(OH)6SO4·xH2O (ZHS) on Zn powder is achieved in pure ZnSO4 electrolyte by facile and rational interface design. The stable and ultrathin ZHS SEI plays a crucial part in insulating water molecules and conducting Zn2+ ions, intrinsically suppressing the severe hydrogen evolution and dendrite formation on the Zn powder anode. The ZHS-Zn anode delivers a stable cycling at a high DOD of 50% for over 500h, as well as a lifespan of over 200h after 40-days of resting at a DOD of 25%. Benefiting from the high utilization of Zn anode, the energy density of the Zn-MnxV2O5 full cell is up to 118WhKg-1. This facile method can fabricate the ZHS-Zn anode as long as 1m, revealing its feasibility in large-scale production and commercialization.

Toward Safe and Reliable Aqueous Ammonium Ion Energy Storage Systems

AbstractAqueous batteries using non‐metallic charge carriers like proton (H+) and ammonium (NH4+) ions are becoming more popular compared to traditional metal‐ion batteries, owing to their enhanced safety, high performance, and sustainability (they are ecofriendly and derived from abundant resources). Ammonium ion energy storage systems (AIBs), which use NH4+ ions with tetrahedral geometry, a small hydrated ionic radius, and relatively low ionic weight, are emerging as strong candidates in non‐metal ion battery chemistry. Various electrode materials (both inorganic and organic) are investigated as hosts for NH4+ ions, however, a comprehensive understanding of these mechanisms is still lacking. This gap limits the ability to optimize performance and identify further research opportunities in AIBs. In this review, the charge storage mechanisms in AIBs are discussed, offering insights into the interactions between NH4+ ions and different electrode materials. Additionally, existing literature on electrode materials, highlighting key structural, and electrochemical achievements are summarized. The review also outlines various electrolytes and examines how their properties influence AIB performance. Finally, the shortcomings of current research are discussed and potential solutions are suggested to advance AIB technology, with the goal of inspiring researchers to explore real‐world applications for ammonium ion batteries.

Accelerating the Development of LLZO in Solid-State Batteries Toward Commercialization: A Comprehensive Review.

Solid-state batteries (SSBs) are under development as high-priority technologies for safe and energy-dense next-generation electrochemical energy storage systems operating over a wide temperature range. Solid-state electrolytes (SSEs) exhibit high thermal stability and, in some cases, the ability to prevent dendrite growth through a physical barrier, and compatibility with the "holy grail" metallic lithium. These unique advantages of SSEs have spurred significant research interests during the last decade. Garnet-type SSEs, that is, Li7La3Zr2O12 (LLZO), are intensively investigated due to their high Li-ion conductivity and exceptional chemical and electrochemical stability against lithium metal anodes. However, poor interfacial contact with cathode materials, undesirable lithium plating along grain boundaries, and moisture-induced chemical degradation greatly hinder the practical implementation of LLZO-based SSEs for SSBs. In this review, the recent advances in synthesis methods, modification strategies, corresponding mechanisms, and applications of garnet-based SSEs in SSBs are critically summarized. Furthermore, a comprehensive evaluation of the challenges and development trends of LLZO-based electrolytes in practical applications is presented to accelerate their development for high-performance SSBs.

Strategies of regulating Zn2+ solvation structures toward advanced aqueous zinc-based batteries

Rechargeable aqueous zinc-based batteries not only pave the way for environmentally friendly and safe energy storage devices but also hold great promise for reducing the manufacturing costs of next-generation batteries, positioning them as the most promising energy storage system to replace lithium-ion batteries. However, the commercial application of aqueous zinc-based batteries (AZBs) is severely constrained by issues such as zinc dendrites, hydrogen evolution reaction (HER), and electrode corrosion. While significant efforts have been devoted to exploring electrode materials and their storage mechanisms in this system in recent years, research on the nature of Zn2+ solvation in electrolytes remains insufficient. Therefore, this review primarily provides a comprehensive and in-depth elucidation of the existing issues such as dendrite formation, hydrogen/oxygen evolution, electrode corrosion and passivation interactions. Additionally, from the perspective of electrolyte optimization, this review emphasizes existing strategies to address Zn2+ solvation, including adjusting electrolyte concentration, incorporating functional additives or co-solvents, utilizing ionic liquids, and developing hydrogel electrolytes, and summarizes approaches and mechanisms for improving their relevant performance. Finally, prospects for electrolyte modification and innovation directions of AZBs are proposed, providing guidance for future AZB studies.

Ionic Conductivity Analysis of NASICON Solid Electrolyte Coated with Polyvinyl-Based Polymers

The global environmental crisis necessitates reliable, sustainable, and safe energy storage solutions. The current systems are nearing their capacity limits due to the reliance on conventional liquid electrolytes, which are fraught with stability and safety concerns, prompting the exploration of solid-state electrolytes, which enable the integration of metal electrodes. Solid-state sodium-ion batteries emerge as an appealing option by leveraging the abundance, low cost, and sustainability of sodium. However, low ionic conductivity and high interfacial resistance currently prevent their widespread adoption. This study explores polyvinyl-based polymers as wetting agents for the NASICON-type NZSP (Na3Zr2Si2PO12) solid electrolyte, resulting in a combined system with enhanced ionic conductivity suitable for Na-ion solid-state full cells. Electrochemical impedance spectroscopy (EIS) performed on symmetric cells employing NZSP paired with different wetting agent compositions demonstrates a significant reduction in interfacial resistance with the use of poly(vinyl acetate)—(PVAc-) based polymers, achieving an impressive ionic conductivity of 1.31 mS cm−1 at room temperature, 63.8% higher than the pristine material, notably reaching 7.36 mS cm−1 at 90 °C. These results offer valuable insights into the potential of PVAc-based polymers for advancing high-performance solid-state sodium-ion batteries by reducing their total internal resistance.

Ti3C2Tx Filled in EMIMBF4 Semi-Solid Polymer Electrolytes for the Zinc-Metal Battery.

Zinc-ion batteries (ZIBs) are promising candidates for safe energy storage applications. However, undesirable parasitic reactions such as dendrite growth, gas evaluation, anode corrosion, and structural damage to the cathode under an acidic microenvironment severely affected cell performance. To resolve these issues, an MXene entrapped in an ionic liquid semi-solid gel polymer electrolyte (GPE) composite was explored. The molecular-level mixing of poly(vinylidene fluoride-co-hexafluoropropylene) (PVHF), zinc trifluoromethanesulfonate (Zn(OTF)2), 1-ethyl-3-methylimidazolium tetrafluoroborate (EMIBF4) ionic liquid, and Ti3C2Tx MXene provided a controlled Zn2+ shuttle toward the anode/cathode. Ti3C2Tx/EMIBF4/Zn(OTF)2/PVHF exhibited a breaking strength of 0.36 MPa with an associated extension of 23%. The Zn//Ti3C2Tx/EMIBF4/Zn(OTF)2/PVHF//Zn symmetric cell with continuous zinc plating/stripping exhibited excellent Zn2+ ion mobility toward the anode and cathode without undesired reactions. This was confirmed by post-mortem analysis after a symmetric cell compatibility test. The as-prepared GPE with a Na3V2(PO4)3 (NVP) cathode exhibited a high chemical diffusion coefficient of 1.14 × 10-7. It also showed an outstanding reversible capacity of 89 mAh g-1 at C/10 with an average discharge plateau voltage of 1.45 V, cycle durability, and controlled self-discharge. These results suggested that the Zn2+ ions in the Ti3C2Tx/EMIBF4/Zn(OTF)2/PVHF composite are reversibly labile in the anode and cathode directions.

Lithium‐Free Redox Flow Batteries: Challenges and Future Prospective for Safe and Efficient Energy Storage

AbstractConsidering the costs, waste, and impact on the environment of current energy consumption, accurate, cost‐effective, and safely deployed energy storage systems are required. Lithium (Li)‐free redox flow batteries (RFBs) are a feasible solution. RFBs can store enormous amounts of energy effectively and are increasingly used for large‐scale applications. The use of RFBs has significantly enhanced the performance of energy storage systems and effectively reduced the costs and wastage of energy storage operations. Vanadium‐based RFBs are an emerging energy‐storage technology being explored for large‐scale deployment owing to their numerous benefits, including zero cross‐contamination, scalability, flexibility, extended life cycle, and nontoxic working state. This study describes the fundamental operating principles of redox flow battery‐based systems as well as the design considerations and constraints placed on each component. It discusses recent progress in the design and deployment of RFBs for energy‐related applications and the remaining obstacles and prospects. Finally, this study highlights the enormous potential of RFBs and suggests some solutions to scale up the use of RFBs in the near future.

Modular Design of Functional Glucose Monomer and Block Co-Polymer toward Stable Zn Anodes.

Aqueous Zn batteries employing mildly acidic electrolytes have emerged as promising contenders for safe and cost-effective energy storage solutions. Nevertheless, the intrinsic reversibility of the Zn anode becomes a focal concern due to the involvement of acidic electrolyte, which triggers Zn corrosion and facilitates the deposition of insulating byproducts. Moreover, the unregulated growth of Zn over cycling amplifies the risk of internal short-circuiting, primarily induced by the formation of Zn dendrites. In this study, a class of glucose-derived monomers and a block copolymer are synthesized through a building-block assembly strategy, ultimately leading to uncover the optimal polymer structure that suppresses the Zn corrosion while allowing efficient ion conduction with a substantial contribution from cation transport. Leveraging these advancements, remarkable enhancements are achieved in the realm of Zn reversibility, exemplified by a spectrum of performance metrics, including robust cycling stability without voltage overshoot and short-circuiting during 3000 h of cycling, stable operation at a high depth of charge/discharge of 75% and a high current density, >95% Coulombic efficiency over 2000 cycles, successful translation of the anode improvement to full cell performance. These polymer designs offer a transformative path based on the modular synthesis of polymeric coatings toward highly reversible Zn anode.

A New Simplified Discrete Fracture Model for Shearing of Intersecting Fractures and Faults

Shearing of fractures and faults is important because it can result in permeability change or even induce seismicity—both are keys for efficient and safe energy recovery and storage in Earth systems. Quantitative analysis of shearing of intersecting fractures and faults is challenging because it can involve dynamic frictional contacts that are complicated by deformation of the rock matrix. To predict the shearing of intersecting fractures/faults, we attempt to answer the question of how intersections impact the shearing of a fracture network and whether we can simplify the description as compared to classical discrete fracture network (DFN) models. To answer these questions, we conducted a series of numerical simulations on scenarios for variable numbers of intersecting fractures. All these examples yield consistent results: the results of using DFNs are consistent with those of using hypothetical major paths. This leads to a new model, which we name simplified discrete fracture network model, to analyze shearing of intersecting fractures/faults using major path(s). We found that the intersections of fractures do not fundamentally change the shearing of two intersecting fractures if the intersecting angles are small. Furthermore, increasing the number of fractures/faults may relax the stress as more fractures/faults become available for shearing and distributing the stress. The simplified DFN model, which can capture efficiently the shearing behavior of each major paths from a large number of intersecting fractures/faults, will be a promising conceptual model that is complementary to existing equivalent continuum and discrete fracture models to analyze shearing of intersecting fractures/faults.

Nickel-mixed chromium sulfide nanoparticle synthesis, characterization, and supercapacitor applications

Researchers are always encouraged to develop new electrode materials to design efficient, safe, and eco-friendly energy storage systems. Doping or mixing is an effective way to improve the electrochemical performance of supercapacitors. In this study, Ni-mixed Cr2S3 (Ni-Cr2S3) nanoparticles were synthesized through a hydrothermal technique with varying molar ratios of Ni and Cr. As prepared different Ni-Cr2S3 nanoparticles were characterized using XRD, XPS, FESEM, TEM, and EDX techniques. The results displayed that the structure and activity of the Ni-Cr2S3 were significantly influenced by the dopant quantity of Ni in Cr2S3. Among a series of Ni-Cr2S3 with various Ni:Cr ratios, the Ni-Cr2S3 (2:1) electrode exhibited a higher specific capacitance of 187.53 F g−1 at 0.5 A g−1 and good operational stability with 93.31 % retention over 5000 charge-discharge cycles. Moreover, the assembled sandwich-type symmetric supercapacitor (Ni-Cr2S3 (2:1)//Ni-Cr2S3 (2:1)) delivered the highest capacitance of 48.0 F g−1 at a current density of 1 A g−1 with excellent cycling performance of 91.26 % and Coulombic efficiency of 99.74 % after 5000 cycles at 5 A g−1. The Ni-Cr2S3 (2:1)//Ni-Cr2S3 (2:1) device possessed the energy/power density of 6.66 Wh kg−1/499.5 W kg−1, when increasing the current density it retained the energy/power density of 1.66 Wh kg−1/2988 W kg−1.

Synthesis and self-assembly of bottlebrush block copolymer electrolytes for solid-state supercapacitors

All-solid-state supercapacitors have attracted increasing attention in recent decades owing to rapid advancements in safe, flexible, and wearable energy storage devices. This study demonstrates a bottlebrush block copolymer electrolyte consisting of poly(styrene-b-butadiene-b-styrene)-g-poly(ethylene glycol) behenyl ether methacrylate (SBS-g-PEGBEM) (simply SgP) for all-solid-state supercapacitors. Due to the adhesive nature and robust mechanical properties of SgP film, devices can be manufactured without the need for separators or packaging. The nonpolar SBS domains serve as scaffolds within the polymer matrix, while the polar PEGBEM domains offer interactive sites for polar ionic liquids (ILs). The synergy between precisely defined nanostructures and the subsequent well-dissociated ions enhances efficient ion transport through the ionic channels. As a result, the supercapacitor with SgP/IL electrolyte exhibits remarkable electrochemical performance. This includes a wide potential window of 2.4 V, an ionic conductivity of 2.4 mS cm−1, and maximum energy density and power density of 28.1 Wh kg−1 and 3080 W kg−1, respectively. The supercapacitor also demonstrates high cycle stability with 87.7 % capacitance retention after 5,000 cycles. The positive impact of the PEGBEM side chains is investigated via molecular dynamics simulations. Thus, this study presents a novel strategy for solid-state electrolytes, offering potential advancements in next-generation energy storage devices.

Improvement of melt quenching technique of Li1+xAlxGe2-x(PO4)3 (LAGP) solid electrolyte for solid-state batteries

Solid-state batteries (SSB) development is the focus area of safe lithium energy storage devices. One of the most promising solid electrolytes for SSBs is Li1+xAlxGe2-x(PO4)3 (LAGP), which stands out for cathode interface stability, air and temperatures stability. However, LAGP ceramic's main challenge remains the low conductivity compared to the bulk phase conductivity. One of the reasons is deviation from stoichiometry due to the loss of volatile components during synthesis and the high synthesis temperature of LAGP-glass. For this reason, the development of methods for obtaining and controlling the composition of LAGPs is required. This study proposes to improve the melt quenching technique by introducing a pre-synthesis stage to obtain LAGP-glass. The effects of pre-synthesis and composition consideration on the structure formation of LAGP were investigated by Fourier-transform infrared spectroscopy. It was shown that NASICON characteristic structural elements had already appeared at the pre-synthesis stage. Through pre-synthesis and component accounting, the synthesis temperature was lowered to 1230 ˚C in 45 minutes. As a result, the polycrystalline Li1,51Al0,51Ge1,75(PO4)2,8 was synthesized with less than 1% side phase content. The conductivity was found to be 5.2·10−4 S·cm−1 (25 ˚C) with cyclic stability exceeding 200 hours at a current density of 200 µA/cm2.

Hierarchical porous N-doped carbon fibers enable ultrafast electron and ion transport for Zn-ion storage at high mass loadings

Zinc-ion capacitors (ZICs) are a promising and safe energy storage system for portable electronics but usually limited by relatively low areal capacity and energy density. Although increasing the mass loading has been suggested, thick electrode layers and clogged pores unavoidably lead to sluggish electron transport and ion diffusion as well as “dead volume” of active materials. Herein, a millimeter-scale 3D thick-network electrode, composed of closely intertwined hierarchical porous N-doped and free-standing carbon nanofibers (HPNCFs), was fabricated via carbonization of nanoscale zeolitic imidazolate framework (ZIF-8) particles embedded in electrospun polyacrylonitrile (PAN) nanofibers. With fast electron/ion transport, large ion-accessible surface area and high utilization rate of active materials, the mass loading of the HPNCFs electrode can reach 48.67 mg cm−2 with a thickness of 4.46 mm. Moreover, the HPNCFs-based ZICs can yield a superior areal/gravimetric capacity of 4.13 F cm−2 /280 F g−1, superior rate capability up to 193.7 F g−1 even at 100 A g−1, high energy density of 99.6 Wh kg−1, and long-term stability for 40,000 cycles. The straightforward approach can provide an opportunity to prepare efficient thick electrodes that could be applied in electrocatalysis, energy storage/conversion, and other electrochemical energy-related techniques.

Lithium-Ion Batteries under the X-ray Lens: Resolving Challenges and Propelling Advancements

The quest for high-performance lithium-ion batteries (LIBs) is at the forefront of energy storage research, necessitating a profound understanding of intricate processes like phase transformations and thermal runaway events. This review paper explores the pivotal role of X-ray spectroscopies in unraveling the mysteries embedded within LIBs, focusing on the utilization of advanced techniques for comprehensive insights. This explores recent advancements in in situ characterization tools, prominently featuring X-ray diffraction (XRD), X-ray tomography (XRT), and transmission X-ray microscopy (TXM). Each technique contributes to a comprehensive understanding of structure, morphology, chemistry, and kinetics in LIBs, offering a selective analysis that optimizes battery electrodes and enhances overall performance. The investigation commences by highlighting the indispensability of tracking phase transformations. Existing challenges in traditional methods, like X-ray absorption spectroscopy (XAS), become evident when faced with nanoscale inhomogeneities during the delithiation process. Recognizing this limitation, the review emphasizes the significance of advanced techniques featuring nanoscale resolution. These tools offer unprecedented insights into material structures and surface chemistry during LIB operation, empowering researchers to address the challenges posed by thermal runaway. Such insights prove critical in unraveling interfacial transport mechanisms and phase transformations, providing a roadmap for the development of safe and high-performance energy storage systems. The integration of X-ray spectroscopies not only enhances our understanding of fundamental processes within LIBs but also propels the development of safer, more efficient, and reliable energy storage solutions. In spite of those benefits, X-ray spectroscopies have some limitations in regard to studying LIBs, as referred to in this review.