Electrochemical Energy Storage Research Articles

Confined Space Dual-Type Quantum Dots for High-Rate Electrochemical Energy Storage.

Owing to quantum size effect and high redox activity, quantum dots (QDs) play very essential roles toward electrochemical energy storage. However, it is very difficult to obtain different-type and uniformly dispersed high-active QDs in a stable conductive microenvironment, because QDs prepared by traditional methods are mostly dissolved in solution or loaded on the surface of other semiconductors. Herein, dual-type semiconductor QDs (Co9S8 and CdS) are skillfully constructed within the interlayer of ultrathin layered double hydroxides (LDH). Inparticular, the expandable interlayer provides a very suitable confined space for the growth and uniform dispersion of QDs, where Co9S8 originates from in-situ transformation of cobalt atoms in laminate and CdS is generated from interlayer pre-embedding Cd2+. Meanwhile, XAFS and GGA+U calculations are employed to explore and prove the mechanism of QDs formation and energy storage characteristics as compared to surface loading QDs. Significantly, the hybrid supercapacitors achieve high energy density of 329.2 μWh cm-2, capacitance retention of 99.1% and coulomb efficiency of 96.9% after 22,000 cycles, which is superior to the reported QDs-based supercapacitors. These findings provide unique insights for designing and developing stable, ordered, and highly active QDs. This article is protected by copyright. All rights reserved.

Agar‐Based Interface for Suppressing Parasitic Reactions toward High‐Performance Aqueous Zn‐Ion Batteries

AbstractWith advantages including high capacity, intrinsic safety and low cost, aqueous zinc‐ion batteries (AZIBs) are ideal electrochemical energy storage devices for large‐scale and portable energy storage. However, the development of AZIBs suffers from tricky challenges, such as the notorious Zn dendrite growth and severe parasitic reactions. Herein, as a low‐cost and nontoxic biomass, agar is adopted to construct an interface layer on Zn foil to mitigate side reactions and induce uniform Zn deposition on Zn anodes. The interaction between Zn2+ and polar functional groups of agar can regulate Zn2+ distribution and promote Zn2+ desolvation, thus simultaneously achieving homogenous Zn deposition and suppressed hydrogen evolution reaction. Meanwhile, SO42− anions are blocked from contacting Zn surface due to electrostatic repulsion, greatly restraining corrosion and passivation. Consequently, Zn||A‐Cu asymmetric cell operates normally for 590 cycles with an average coulombic efficiency of 99.5 %, suggesting good reversibility of Zn plating/stripping. Notably, A‐Zn symmetric cell exhibits a long lifespan of 1100 h at 2 mA cm−2. Furthermore, the A‐Zn||NVO full cell displays a superb capacity retention of 94.8 % after 3600 cycles at 5 A g−1. This work offers a novel interface modification method for constructing stable and dendrite‐free anodes of AZIBs.

Dealloyed nickel skeleton hosting in-situ formed multimetallic phosphides for enhanced electrochemical energy storage

Transition metal phosphides (TMPs) exhibit considerable potential in supercapacitors (SCs) electrodes fabrication due to their high power densities and conducive ion transport, positioning them as quintessential candidates for such application. Despite their promise, monometallic phosphides require further electrochemical performance enhancements. This work unveils an innovative strategy for synthesizing complex cobalt/nickel phosphides directly on a nickel skeleton (Ni@NCP), achieved by the selectively leaching copper from a Ni–Cu alloy via a dealloying process after electrodeposition, significantly improving electrochemical performance through increased electroactive sites and optimized ion diffusion channels. The Ni@NCP electrode exhibits an impressive specific capacitance of 612 F g−1 at a high current density of 20 A g−1. Furthermore, the unique hollow nanotube structure greatly enhances cyclic stability, maintaining 80.1 % capacity after 10,000 cycles at 10 A g−1. This research presents a methodical approach to electrode material synthesis, emphasizing the construction of supportive frameworks and active sites, thereby underscoring the substantial potential for advancements in SC electrode technology.

A Hybrid-Salt Strategy for Modulating the Li+ Solvation Sheathes and Constructing Robust SEI in Non-Flammable Electrolyte Lithium Metal Batteries.

The electrode interface determines the performance of an electrochemical energy storage system. Using traditional electrolyte organic additives and high-concentration electrolyte emerging recently are two generally strategies for improving the electrode interface. Here, a hybrid-salt electrolyte strategy is proposed for constructing the stable electrode interface. Through the solubilization effect of phosphate ester on LiNO3, a hybrid-salts-based non-flammable phosphate ester electrolyte system (HSPE) with LiPF6 and LiNO3 as Li salts has been developed. By the strong interaction between NO3 - and Li+, the Li+ solvation sheath and solvent behaviors have been modulated, thus the undesirable effects of phosphate ester are eliminated and a robust SEI is formed. Experimental results and theoretical calculations illustrate that NO3 - as a kind of strongly coordinating anion can reduce the number of TEP molecules and lower the reduction reactivity of TEP. The reconfigured Li+ solvation structure allows the formation of an inorganic-rich SEI on the electrode surface. As a result, in the designed HSPE, the average coulombic efficiency of lithium plating/stripping is increased to 99.12 %. This work explored a new approach to construct the electrode interface and addressing the poor interface performance issue of phosphate esters.

Freestanding Ammonium Vanadate Composite Cathodes with Lattice Self-Regulation and Ion Exchange for Long-Lasting Ca-Ion Batteries.

Calcium-ion batteries (CIBs) have emerged as a promising alternative for electrochemical energy storage. The lack of high-performance cathode materials severely limits the development of CIBs. Vanadium oxides are particularly attractive as cathode materials for CIBs, and preinsertion chemistry is often used to improve their calcium storage performance. However, the room temperature cycling lifespan of vanadium oxides in organic electrolytes still falls short of 1000 cycles. Here, based on preinsertion chemistry, the cycling life of vanadium oxides is further improved by integrated electrode and electrolyte engineering. Utilizing a tailored Ca electrolyte, the constructed freestanding (NH4)2V6O16·1.35H2O@graphene oxide@carbon nanotube (NHVO-H@GO@CNT) composite cathode achieves a 305 mAh g-1 high capacity and 10000 cycles record-long life. Additionally, for the first time, a Ca-ion hybrid capacitor full cell is assembled and delivers a capacity of 62.8 mAh g-1. The calcium storage mechanism of NHVO-H@GO@CNT based on a two-phase reaction and the exchange of NH4 + and Ca2+ during cycling are revealed. The lattice self-regulation of V─O layers is observed and the layered vanadium oxides with Ca2+ pillars formed by ion exchange exhibit higher capacity. This work provides novel strategies to enhance the calcium storage performance of vanadium oxides via integrated structural design of electrodes and electrolyte modification.

Recyclable organic radical electrodes for metal-free batteries.

Organic batteries are one of the possible routes for transitioning to sustainable energy storage solutions. However, the recycling of organic batteries, which is a key step toward achieving circularity, is not easily achieved. This work shows the direct recycling of poly(2,2,6,6-tetramethylpiperidinyloxy-4-yl) (PTMA) and poly(2,2,6,6-tetramethylpiperidinyloxy-4-yl acrylamide) (PTAm) based composite electrodes. After charge-discharge cycling, the electrodes are deconstructed using a solubilizing-solvent and then reconstructed using a casting-solvent. The electrochemical properties of the original and recycled electrodes are compared using cyclic voltammetry (CV) and galvanostatic charge-discharge (GCD) cycling, from which it is discovered using time-of-flight secondary ion mass spectrometry (ToF-SIMS) that recycling can be challenged by the formation of a solid-electrolyte interphase (SEI). In turn, an additive is proposed to modify the SEI layer and improve the properties after recycling. Last, an anionic rocking chair battery consisting of PTAm electrodes as both positive and negative electrodes is demonstrated, in which the electrodes are recycled to form new battery. This work gives demonstrates the recycling of composite electrodes for organic batteries and provides insights into the challenges and possible solutions for recycling the next-generation electrochemical energy storage devices.

Design Strategies for Anti‐Freeze Electrolytes in Aqueous Energy Storage Devices at Low Temperatures

AbstractWith the continuous development of electrochemical energy storage technology, especially in the current pursuit of environmental sustainability and safety, aqueous energy storage devices, due to their high safety, environmental friendliness, and cost‐effectiveness, are becoming an important direction of development in the field of energy storage. Diverse application scenarios require that energy storage systems be capable of continuous power supply under low temperature conditions. However, conventional aqueous electrolytes freeze at extremely low temperatures, causing limited ion transport and slow reaction kinetics, degrading the performance of the energy storage system. The design of low‐temperature anti‐freeze aqueous electrolytes has become an effective way to address this issue. In this review, the deep connection between hydrogen bonds (HBs) interactions in aqueous electrolytes and the liquid‐to‐solid conversion process, and the fundamental principles of the anti‐freeze mechanism is first explored. Subsequently, a systematic categorization and discussion of the design strategies for low‐temperature anti‐freeze aqueous electrolytes are conducted. Finally, potential directions are proposed. This review aims to provide comprehensive scientific guidance and technical reference for the development of anti‐freeze aqueous electrolytes with excellent low‐temperature performance, thereby promoting the application and innovation of aqueous energy storage devices in low‐temperature environments.

Enhancement of Li/S Battery Performance by a Modified Reduced Graphene Oxide Carbon Host Decorated with MoO3.

Electrochemical energy storage systems based on sulfur and lithium can theoretically delivery high energy with the further benefit of low cost. However, the working mechanism of this device involves the dissolutions of sulfur to high-molecular weight lithium polysulfide (LiPs with general formula Li2Sn, n>4) in the electrolyte during the discharge process. Therefore, the resulting migration of partially dissociated LiPs, by diffusion or under the effect of the electric field, to the lithium anode activates an internal shuttle mechanism, reduces the active material and in general leads to loss of performance and a reduced cycling stability. These drawbacks poses challenges to the commercialization of Li/S cells in the short term. In this study, we report on the decoration of reduced graphene oxide with MoO3 particles to enhance interactions with LiPs and retain sulfur at the cathode side. The combination of experiments and density functional theory calculation demonstrated improvements in binding interactions between the cathode and sulfur species, enhancing the cycling stability of the Li/S half-cell.

Enhanced Supercapacitive Performance in Catalyst‐Free Binary Composite SnO2–RuO2 Nanostructured Thin Films for Symmetric Supercapacitor Device

In the present work, thin film electrodes of ruthenium oxide (RuO2), tin oxide (SnO2), and their composite SnO2–RuO2 are deposited on 304 stainless steel substrates using pulsed laser deposition (PLD). These nanostructured electrodes are then evaluated for their suitability in electrochemical energy storage applications. A symmetric supercapacitor device (SSD) is constructed using the SnO2–RuO2 composite electrodes. Compared to individual SnO2 and RuO2 electrodes, the composite electrodes exhibit enhanced specific capacitance and cycle life. This improvement is attributed to modifications in surface morphology and electronic properties. This modified surface morphology of the composite electrode, creates favourable conditions for electrolyte interaction and ion transport, ultimately contributing to the observed increase in specific capacitance. Specifically, the composite electrode demonstrates a specific capacitance of 170.2 Fg−1 at a current density of 0.1 mA cm−2, outperforming SnO2 (37.4 Fg−1). The SnO2–RuO2//SnO2–RuO2 SSD exhibites a specific capacitance of 70.0 Fg−1 at a current density of 0.1 mA cm−2, coupled with energy density and power density values of 19.05 Wh kg−1 and 645 W kg−1, respectively, within a voltage window of 1.4 V. The SSD displays an impressive capacitive retention of 81.27% over 10 000 cycles, indicating its potential for practical energy storage applications.

Optimal charging for lithium-ion batteries to avoid lithium plating based on ultrasound-assisted diagnosis and model predictive control

Lithium plating in lithium-ion batteries for electric vehicles, occurring due to low-temperature or high-rate charging, is a significant factor impacting safety and service life. To address this issue, a novel adaptive charging approach is proposed, combining ultrasound-assisted diagnosis and model predictive control (MPC). In the method, a discrete state-space electrochemical model is used to describe the dynamic characteristics of the battery, and a model predictive controller (MPC) is utilized to optimize the charging current to avoid lithium plating. Considering that factors such as battery performance degradation and variable working temperature affect the battery model's judgment of lithium plating, an ultrasound-assisted diagnosis method is used to determine the critical point of lithium plating. The effectiveness of the method is validated through low-temperature charging and cycle aging experiments. The results indicate that without complex model parameter calibration in different temperatures, the new charging method not only has a higher charging speed than constant current charging, but also can effectively suppress the occurrence of lithium plating on the negative electrode of the battery. The method is expected to be applied in electrochemical energy storage systems to enhance safety and service life.

Development of Electrolytes under Lean Condition in Lithium-Sulfur Batteries.

Lithium-sulfur (Li-S) batteries stand out as one of the promising candidates for next-generation electrochemical energy storage technologies. A key requirement to realize high-specific-energy Li-S batteries is to implement low amount of electrolyte, often characterized by the electrolyte/sulfur (E/S) ratio. Low E/S ratio aggravates the known challenges for Li-S batteries and introduces new ones originated from the high concentration of polysulfides in limited electrolyte reservoir. In this review, the connections between the fundamental properties of electrolytes and the electrochemical/chemical reactions in Li-S batteries under lean electrolyte condition are elucidated. The emphasis is on how the solvating properties of the electrolyte affect the fate of polysulfides. Built upon the mechanistic analysis, different strategies to design lean electrolytes to improve the overall process of Li-S reactions and Li anode protection are discussed.

Rational design of hierarchical porous reduced graphene oxide/9,10-phenanthraquinone/porous carbon nanocomposites for high-performance supercapacitors

The development of advanced electrode material is crucial for promoting the application of new high-performance green energy storage devices and remains a great challenge. Herein, by introducing porous carbon (PC) or carbon nanotubes (CNTs) to further modify the redox-active 9,10-phenanthrenequinone (PQ) molecule non-covalently functionalized reduced graphene oxide (RGO), we have designed and synthesized RGO/PQ/PCs (RPPs) and RGO/PQ/CNTs-10 (RPC-10) nanocomposites using a simple one-step solvothermal method. Benefiting from the optimization of the hierarchical porous nanostructures and each composition further strengthens their respective advantages in the novel synthesized nanocomposites (RPPs and RPC-10), the RPPs and RPC-10 electrodes demonstrated significantly superior electrochemical energy storage performance over the RGO and RGO/PQ (RP) electrodes, especially for the RPP-10 electrode with a high specific capacitance of 343.5 F g−1 at 0.5 A g−1 and good rate capability (69.23 %, 0.5 − 40 A g−1). Furthermore, both the symmetric supercapacitor assembled with the optimal RPP-10 electrode and the hybrid supercapacitor assembled with the RPP-10 negative electrode and the NCSRC-24 positive electrode previously reported show excellent energy densities and ultra-long cycling stabilities. This result demonstrates that the synthesized novel RPP-10 nanocomposite is a highly promising candidate for new light-weight, sustainable, high-flexible and high-performance energy storage devices.

Sub-nanopores enabling optimized ion storage performance of carbon cathodes for Zn-ion hybrid supercapacitors

Aqueous Zn-ion hybrid supercapacitors (ZHSs) are attracting significant attention as a promising electrochemical energy storage system. However, carbon cathodes of ZHSs exhibit unsatisfactory ion storage performance due to the large size of hydrated Zn-ions (e.g., [Zn(H2O)6]2+), which encumbers compact ion arrangement and rapid ion transport at the carbon-electrolyte interfaces. Herein, a porous carbon material (HMFC) with abundant sub-nanopores is synthesized to optimize the ion storage performance of the carbon cathode in ZHSs, in which the sub-nanopores effectively promote the dehydration of hydrated Zn-ions and thus optimize the ion storage performance of the carbon cathode in ZHSs. A novel strategy is proposed to study the dehydration behaviors of hydrated Zn-ions in carbon cathodes, including quantitatively determining the desolvation activation energy of hydrated Zn-ions and in-situ monitoring active water content at the carbon-electrolyte interface. The sub-nanopores-induced desolvation effect is verified, and its coupling with large specific surface area and hierarchically porous structure endows the HMFC cathode with improved electrochemical performance, including a 53 % capacity increase compared to the carbon cathode counterpart without sub-nanopores, fast charge/discharge ability that can output 46.0 Wh/kg energy within only 4.4 s, and 98.2 % capacity retention over 20,000 charge/discharge cycles. This work provides new insights into the rational design of porous carbon cathode materials toward high-performance ZHSs.

Nanoporous Carbon Materials Derived from Zanthoxylum Bungeanum Peel and Seed for Electrochemical Supercapacitors

In order to prepare biomass-derived carbon materials with high specific capacitance at a low activation temperature (≤700 °C), nanoporous carbon materials were prepared from zanthoxylum bungeanum peels and seeds via the pyrolysis and KOH-activation processes. The results show that the optimal activation temperatures are 700 °C and 600 °C for peels and seeds. Benefiting from the hierarchical pore structure (micropores, mesopores, and macropores), the abundant heteroatoms (N, S, and O) containing functional groups, and plentiful electrochemical active sites, the PAC-700 and SAC-600 derive the large capacities of ~211.0 and ~219.7 F g−1 at 1.0 A g−1 in 6 M KOH within the three-electrode configuration. Furthermore, the symmetrical supercapacitors display a high energy density of 22.9 and 22.4 Wh kg−1 at 7500 W kg−1 assembled with PAC-700 and SAC-600, along with exceptional capacitance retention of 99.1% and 93.4% over 10,000 cycles at 1.0 A g−1. More significantly, the contribution here will stimulate the extensive development of low-temperature activation processes and nanoporous carbon materials for electrochemical energy storage and beyond.

Synthesis of Ni3V2O8-rGO composite nanostructure for high-performance hybrid supercapacitors via hydrothermal method

To address global energy demand, major efforts have been made to develop cutting-edge electrode materials for electrochemical energy storage (EES) devices. The present article discusses the hydrothermal synthesis of bare nickel vanadate and a nickel vanadate/reduced graphene oxide (Ni3V2O8-rGO) composite for supercapacitor applications. The physicochemical properties of pure Ni3V2O8 (NVO) and the Ni3V2O8-rGO (NVO-rGO) composite were investigated using a variety of characterization tools. The electrochemical traits of the NVO-rGO composite outperform bare NVO due to the synergistic effect. At a current density of 1 mAcm−2, the NVO and NVO-rGO nanostructures exhibit excellent specific capacitances of 85 Fg−1 and 108 Fg−1, respectively. These nanostructures also have energy densities of about 3.82 and 5.02 WhKg−1, with power densities of 141.75 and 151.57 WKg−1 for NVO and NVO-rGO composite, respectively. Electrochemical impedance spectroscopy (EIS) studies revealed a charge resistance of 2.05 Ω. The transfer coefficient and standard rate constant indicate that the charge storage mechanism is based on a quasi-reversible redox process. The present investigation demonstrates that the NVO-rGO composite has exceptional electrochemical performance. The outstanding electrochemical performance of both NVO and NVO-rGO underlines their potential as novel and promising materials for supercapacitor applications, implying significant feasibility for large-scale utilization.

Freeze-drying synthesis of metal element (Zr, Cr, Co)–doped Li4Ti5O12 anode material for enhanced electrochemical energy storage in lithium-ion batteries

Freeze-drying synthesis of metal element (Zr, Cr, Co)–doped Li4Ti5O12 anode material for enhanced electrochemical energy storage in lithium-ion batteries

A review of EDLC and pseudocapacitance with synergistic integration of carbon-based and metal oxide materials for enhanced electrochemical energy storage

This paper provides a comprehensive analysis of the recent advancements in electrochemical double-layer capacitors (EDLCs) and pseudocapacitance, emphasizing the pivotal role of carbon-based materials, metal oxides, conducting polymers, and composites in augmenting the energy storage landscape. Through a systematic collection of electrochemical performance metrics, we elucidate the inherent advantages of these materials, such as superior electrical conductivity, enhanced surface area, and chemical robustness, which are instrumental in the development of next-generation supercapacitors. We discuss the integration of novel materials like reduced graphene oxide/hexagonal boron nitride composites, carbon onions, and various metal oxides that contribute to a significant increase in energy density and cycling stability. This work also highlights innovative fabrication techniques and synthesis methodologies that have resulted in electrodes with remarkable performance enhancements. Furthermore, the exploration of synergistic effects between different materials has led to hybrid structures that exhibit improved capacitive properties and operational efficiency.

Layer-by-layer assembling redox wood electrodes for efficient energy storage

The exploration of redox-active organic materials and low tortuous thick-electrodes is attractive for energy storage. The in-situ valorized lignin on raw wood surface accompanied by layer-by-layer deposition of electro-active materials endow such spatially distributed wood electrodes with high specific capacitance. Here, we report a layer-by-layer assembled ca.1.5 mm-thick redox wood hybrid electrode with 20 mg cm-2 electro-active mass loading for efficient energy storage. The in-situ modified surface lignin in treated wood (TrW) holds promise as redox-active material with enriched nanoporosity, carbonyl functionalities, and multi-phase ionic transport structure. The carbon nanotubes (CNTs) networking with in-situ polymerized polypyrrole (PPy) nanorods three-dimensionally in the lumen of TrW afford a wool-like, highly porous nanostructure. Such a hierarchical structured PPy@CNTs@TrW electrode offers a high areal capacitance of 1.46 F cm-2 with an extraordinary energy density of 0.983 mWh cm-3 (3.68 Wh kg-1) and power density of 5.4 mW cm-3 (20.25 W kg-1). Here, the valorized surface lignin contributes contributes to electrochemical energy storage accompanied by spatially distributed PPy@CNTs in low tortuous electrodes. The electrode offers extremely low electrochemical impedance of 0.61 Ω electrode resistance and 1.57 Ω electrolyte resistance. The hybrid wood electrode showcases even higher conductivity and energy/power density than thin carbonized wood and other state-of-the-art thin electrodes made of highly conductive three-dimensional networks. This work highlights the potential of in-situ valorized lignin in developing high-performance eco-friendly thick-electrodes for electrochemical energy storage applications.

The current state of transition metal-based electrocatalysts (oxides, alloys, POMs, and MOFs) for oxygen reduction, oxygen evolution, and hydrogen evolution reactions

Climate change is showing its impacts now more than ever. The intense use of fossil fuels and the resulting CO2 emissions are mainly to blame, accentuating the need to develop further the available energy conversion and storage technologies, which are regarded as effective solutions to maximize the use of intermittent renewable energy sources and reduce global CO2 emissions. This work comprehensively overviews the most recent progress and trends in the use of transition metal-based electrocatalysts for three crucial reactions in electrochemical energy conversion and storage, namely, the oxygen evolution (OER), oxygen reduction (ORR), and hydrogen evolution (HER) reactions. By analyzing the state-of-the-art polyoxometalates (POMs) and metal-organic frameworks (MOFs), the performance of these two promising types of materials for OER, ORR, and HER is compared to that of more traditional transition metal oxides and alloy-based electrocatalysts. Both catalytic activity and stability are highly influenced by the adsorption energies of the intermediate species formed in each reaction, which are very sensitive to changes in the microstructure and chemical microenvironment. POMs and MOFs allow these aspects to be easily modified to fine-tune the catalytic performances. Therefore, their chemical tunability and versatility make it possible to tailor such properties to obtain higher electrocatalytic activities, or even to obtain derived materials with more compelling properties towards these reactions.

MOF‐derived Porous Carbon for Zinc‐ion Hybrid Capacitors with Ultra‐high Energy Density and Long Cycling Life

Zinc‐ion hybrid capacitors (ZHC) have been considered as emerging sustainable electrochemical energy storage devices. They integrate the benefits of high‐energy density of aqueous zinc ion battery (ZIB) with high‐power density of supercapacitor (SC). Metal‐organic frameworks (MOFs) have been widely used to design electrode materials for portable devices, especially in some energy storage fields because of their large specific surface area and adjustable pore structures. In this work, we prepare porous Mn3O4/C nanosheets with Mn‐BDC as a precursor. The assembled device delivers a specific capacitance of 155.3 mAh g‐1 at a current of 3 A g‐1 and keeps a retention rate of 97.7% after 10,000 cycles. Moreover, it provides an energy density of 464.5 Wh kg‐l at a power density of 100 W kg‐1.