Search Results (45)

Lithium-ion batteries are extensively employed in new energy vehicles, where accurate State of Charge (SOC) estimation is fundamental for optimal battery management. However, existing methods often rely on single-model approaches and fail to leverage the complementary advantages of multiple models. This study proposes an innovative hybrid estimation model integrating a Temporal Convolutional Network (TCN) that efficiently captures long-range temporal dependencies via dilated convolution and residual blocks, with a Bidirectional Long Short-Term Memory Network (BiLSTM) that extracts bidirectional context information to enhance the accuracy of SOC estimation. First, the Panasonic datasets are utilized, with current, voltage, and cell temperature selected as input features. Subsequently, the proposed model is evaluated under various temperature conditions and driving cycles, demonstrating high accuracy and robustness. Finally, comparative experiments are conducted against traditional methods, such as standalone TCN and Long Short-Term Memory (LSTM) networks, under both 10 °C and −10 °C operating conditions. The results show that the hybrid model achieves superior performance in error metrics. Specifically, based on a second-order resistor-capacitor network, at −10 °C, the Root Mean Squared Error is reduced by 0.948%, and at 10 °C, it decreases by 0.398%. Additionally, the Maximum Absolute Error is lowered by 2.751% at −10 °C and by 2.192% at 10 °C. These improvements highlight the model’s significant potential as an effective solution for SOC estimation in lithium-ion batteries. Full article

Battery cell balancing is crucial in series-connected lithium-ion packs to maximize usable capacity, ensure safe operation, and prolong cycle life. This paper presents a comprehensive study and a novel adaptive duty-cycled hybrid balancing system that combines passive bleed resistors and an active switched-capacitor (SC) balancer, specifically designed for a 4-cell series-connected battery pack. This work also explored open circuit voltage (OCV)-driven adaptive pulse-frequency modulation (PFM) active balancing to achieve higher efficiency and better balancing speed based on different system requirements. Finally, this paper compares passive, active (SC-based), and adaptive duty-cycled hybrid balancing strategies in detail, including theoretical modeling of energy transfer and efficiency for each method. Simulation showed that the adaptive hybrid balancer speeds state-of-charge (SoC) equalization by 16.24% compared to active-only balancing while maintaining an efficiency of 97.71% with minimal thermal stress. The simulation result also showed that adaptive active balancing was able to achieve a high efficiency of 99.86% and provided an additional design degree of freedom for different applications. The results indicate that the adaptive hybrid balancer offered an excellent trade-off between balancing speed, efficiency, and implementation simplicity for 4-cell Li-ion packs, making it highly suitable for applications such as high-voltage portable chargers. Full article

Accurate parametric modeling of lithium-ion batteries is essential for battery management system (BMS) design in electric vehicles and broader energy storage applications, enabling reliable state estimation and effective thermal control under diverse operating conditions. This study presents a detailed characterization of lithium-ion cells to support advanced BMS in electric vehicles and stationary storage. A second-order equivalent circuit model is developed to capture instantaneous and dynamic voltage behavior, with parameters extracted through Hybrid Pulse Power Characterization over a broad range of temperatures (−10 °C to 45 °C) and state-of-charge levels. The method includes multi-duration pulse testing and separates ohmic and transient responses using two resistor–capacitor branches, with parameters tied to physical processes like charge transfer and diffusion. A weakly coupled electro-thermal model is presented to support real-time BMS applications, enabling accurate voltage, temperature, and heat generation prediction. This study also evaluates open-circuit voltage and direct current internal resistance across pulse durations, leading to power capability maps (“fish charts”) that capture discharge and regenerative performance across SOC and temperature. The analysis highlights performance asymmetries between charging and discharging and confirms model accuracy through curve fitting across test conditions. These contributions enhance model realism, thermal control, and power estimation for real-world lithium-ion battery applications. Full article

Metal-ion capacitors (MICs) have emerged as advanced hybrid energy storage devices that combine the high energy density of batteries with the superior power density and long cycle life of supercapacitors. By leveraging a unique configuration of faradaic and non-faradaic energy storage mechanisms, MICs offer a balanced performance that meets the diverse requirements of modern applications, including renewable energy systems, electric vehicles, and portable electronics. MICs employ diverse ions such as lithium, sodium, and potassium, which provide flexibility in material selection, scalability, and cost-effectiveness. For instance, lithium-ion capacitors (LICs) excel in compact and high-performance applications, while sodium-ion (NICs) and potassium-ion capacitors (KICs) provide sustainable and affordable solutions for large-scale energy storage. This review highlights the advancements in electrode materials, including carbon-based materials, transition metal oxides, and emerging candidates like MXenes and metal–organic frameworks (MOFs), which enhance MIC performance. The role of electrolytes, ranging from organic and aqueous to hybrid and solid-state systems, is also examined, emphasizing their influence on energy density, safety, and operating voltage. Additionally, the article discusses the environmental and economic benefits of MICs, including the use of earth-abundant materials and bio-derived carbons, which align with global sustainability goals. The review concludes with an analysis of practical applications, commercialization challenges, and future research directions, including AI-driven material discovery and integration into decentralized energy systems. As versatile and transformative energy storage devices, MICs are poised to play a critical role in advancing sustainable and efficient energy solutions for the future. Full article

Most European Union governments and numerous railway operators have announced plans to replace most of their diesel units by 2030–2040. However, a significant portion of the rail network remains non-electrified. In some cases, the proposed solution has been to close certain tracks, but this approach entails considerable societal costs for small cities and represents a loss of prior railway investments. Consequently, hybrid locomotives and multiple units (either new or refurbished) emerge as a viable solution during this transitional period to enhance energy efficiency and preserve services on these lines, particularly for freight operations. These hybrid units can operate on both electrified and non-electrified tracks and can also serve as “railway prosumers”, contributing to both storage and generation in fully or partially electrified areas. However, implementing these “prosumer tasks” faces challenges, such as the rapid power demand fluctuations during acceleration and the loss of energy recovery potential during braking in hybrid or fully electric units. These losses may also impact the overall power system. This paper presents an alternative approach to modeling double-layer capacitors (supercapacitors) combined with electrical equivalent models for lithium-ion batteries. The Differential Transformation Method (DTM) is used to solve the non-linear ordinary differential equations governing the supercapacitor model, while parameter optimization is achieved through a grid search approach, demonstrating high accuracy compared with laboratory trials. This framework highlights the potential of hybrid units, as illustrated through simulations that analyze storage sizing, energy management, increased energy recovery, and changes in unit performance. These models facilitate a pre-feasibility evaluation of energy storage systems for hybrid railway applications. Full article

The ever-increasing global energy demand necessitates the development of efficient, sustainable, and high-performance energy storage systems. Nanotechnology, through the manipulation of materials at the nanoscale, offers significant potential for enhancing the performance of energy storage devices due to unique properties such as increased surface area and improved conductivity. This review paper investigates the crucial role of nanotechnology in advancing energy storage technologies, with a specific focus on capacitors and batteries, including lithium-ion, sodium–sulfur, and redox flow. We explore the diverse applications of nanomaterials in batteries, encompassing electrode materials (e.g., carbon nanotubes, metal oxides), electrolytes, and separators. To address challenges like interfacial side reactions, advanced nanostructured materials are being developed. We also delve into various manufacturing methods for nanomaterials, including top–down (e.g., ball milling), bottom–up (e.g., chemical vapor deposition), and hybrid approaches, highlighting their scalability considerations. While challenges such as cost-effectiveness and environmental concerns persist, the outlook for nanotechnology in energy storage remains promising, with emerging trends including solid-state batteries and the integration of nanomaterials with artificial intelligence for optimized energy storage. Full article

Lithium-ion capacitors (LICs) are emerging as promising hybrid energy storage devices that combine the high energy densities of lithium-ion batteries (LIBs) with high power densities of supercapacitors (SCs). Nevertheless, the development of LICs is hindered by the kinetic imbalances between battery-type anodes and capacitor-type cathodes. To address this issue, honeycomb-like N-doped carbon matrices encapsulating Co_1−xS/Co(PO₃)₂ heterostructures were prepared using a simple chemical blowing-vulcanization process followed by phosphorylation treatment (Co_1−xS/Co(PO₃)₂@NC). The Co_1−xS/Co(PO₃)₂@NC features a unique heterostructure engineered within carbon honeycomb structures, which efficiently promotes charge transfer at the interfaces, alleviates the volume expansion of Co-based materials, and accelerates reaction kinetics. The optimal Co_1−xS/Co(PO₃)₂@NC composite demonstrates a stable reversible capacity of 371.8 mAh g⁻¹ after 800 cycles at 1 A g⁻¹, and exhibits an excellent rate performance of 242.9 mAh g⁻¹ even at 8 A g⁻¹, alongside enhanced pseudocapacitive behavior. The assembled Co_1−xS/Co(PO₃)₂@NC//AC LIC delivers a high energy density of 90.47 Wh kg⁻¹ (at 26.28 W kg⁻¹), a high power density of 504.94 W kg⁻¹ (at 38.31 Wh kg⁻¹), and a remarkable cyclic stablitiy of 86.3% retention after 5000 cycles. This research is expected to provide valuable insights into the design of conversion-type electrode materials for future energy storage applications. Full article

The growing demands for electrochemical energy storage systems is driving the exploration of novel devices, with lithium-ion capacitors (LICs) emerging as a promising strategy to achieve both high energy density and fast charge capability. However, the low capacitance of commercial activated carbon (AC) cathode based on anion absorption/desorption limits LIC applications. Herein, commercial graphite is proposed as the cathode to construct an innovative AC (−)//graphite (+) system. The graphite cathode functions as anion hosting, allowing reversible intercalation/de-intercalation of anions into/from its interlayers. The as-designed AC (−)//graphite (+) full cell achieves stable cycling with 90.6% capacity retention after 200 cycles at 0.1 A g⁻¹ and a prolonged lifespan with 87.5% capacity retention after 5000 cycles at 0.5 A g⁻¹ with the upper cut-off voltage of 5.0 V, yielding a high average Coulombic efficiency (CE) of 99.3%. Moreover, the full cell exhibits a high energy density (>200 Wh kg⁻¹) and power density of 7.7 kW kg⁻¹ (calculated based on active mass in both electrodes). These performances exceed most LICs based on anions absorption/desorption on the surface of AC cathodes. This work explores an effective electrode revolution with the assistance of anion intercalation/de-intercalation chemistry for developing novel LICs with high energy and power densities. Full article

Capacitors exhibit exceptional power density, a vast operational temperature range, remarkable reliability, lightweight construction, and high efficiency, making them extensively utilized in the realm of energy storage. There exist two primary categories of energy storage capacitors: dielectric capacitors and supercapacitors. Dielectric capacitors encompass film capacitors, ceramic dielectric capacitors, and electrolytic capacitors, whereas supercapacitors can be further categorized into double-layer capacitors, pseudocapacitors, and hybrid capacitors. These capacitors exhibit diverse operational principles and performance characteristics, subsequently dictating their specific application scenarios. To make informed decisions in selecting capacitors for practical applications, a comprehensive knowledge of their structure and operational principles is imperative. Consequently, this review delved into the structure, working principles, and unique characteristics of the aforementioned capacitors, aiming to clarify the distinctions between dielectric capacitors, supercapacitors, and lithium-ion capacitors. Full article

This paper proposes a hybrid power supply system for commercial drones. The proposed hybrid power supply system consists of a lithium polymer battery, a supercapacitor, and a power converter for charging the supercapacitor. In the proposed system, the supercapacitor is pre-charged with a lithium polymer battery through a power converter, and the supercapacitor first supplies the power required for the drone’s initial startup and lift-up. Afterward, in the section where the power consumption of the drone is low, the battery and the supercapacitor supply power together, minimizing the stress on the battery. To verify the proposed hybrid power supply system, a computer simulation was conducted, the actual hardware was fabricated, and experiments were performed. Full article

Lithium-ion capacitors (LiC) are promising hybrid devices bridging the gap between batteries and supercapacitors by offering simultaneous high specific power and specific energy. However, an indispensable critical component in LiC is the capacitive cathode for high power. Activated carbon (AC) is typically the cathode material due to its low cost, abundant raw material for production, sustainability, easily tunable properties, and scalability. However, compared to conventional battery-type cathodes, the low capacity of AC remains a limiting factor for improving the specific energy of LiC to match the battery counterparts. This review discusses recent approaches for achieving high-performance LiC, focusing on the AC cathode. The strategies are discussed with respect to active material property modifications, electrodes, electrolytes, and cell design techniques which have improved the AC’s capacity/capacitance, operating potential window, and electrochemical stability. Potential strategies and pathways for improved performance of the AC are pinpointed. Full article

Lithium-ion capacitors (LICs) are emerging as one of the most advanced hybrid energy storage devices, however, their development is limited by the imbalance of the dynamics and capacity between the anode and cathode electrodes. Herein, anthracite was proposed as the raw material to prepare coal-based, nitrogen-doped porous carbon materials (CNPCs), together with being employed as a cathode and anode used for dual-carbon lithium-ion capacitors (DC-LICs). The prepared CNPCs exhibited a folded carbon nanosheet structure and the pores could be well regulated by changing the additional amount of g-C₃N₄, showing a high conductivity, abundant heteroatoms, and a large specific surface area. As expected, the optimized CNPCs (CTK-1.0) delivered a superior lithium storage capacity, which exhibited a high specific capacity of 750 mAh g⁻¹ and maintained an excellent capacity retention rate of 97% after 800 cycles. Furthermore, DC-LICs (CTK-1.0//CTK-1.0) were assembled using the CTK-1.0 as both cathode and anode electrodes to match well in terms of internal kinetics and capacity simultaneously, which displayed a maximum energy density of 137.6 Wh kg⁻¹ and a protracted lifetime of 3000 cycles. This work demonstrates the great potential of coal-based carbon materials for electrochemical energy storage devices and also provides a new way for the high value-added utilization of coal materials. Full article

Hybrid lithium-ion capacitors (HyLICs) have received considerable attention because of their ability to combine the advantages of high-energy lithium-ion batteries and high-power supercapacitors. State of charge (SOC) is the main factor affecting the practical application of HyLICs; therefore, it is essential to estimate the SOC accurately. In this paper, a partition SOC-estimation method that combines electrochemical and external characteristics is proposed. The discharge process of the HyLICs was divided into three phases based on test results of electrochemical characteristics. To improve the estimation accuracy and reduce the amount of calculation, the Extended Kalman Filter (EKF) method was applied for SOC estimation at the interval where the capacitor energy storage characteristics dominated, and the Ampere-hour (Ah) method was used to estimate the SOC at the interval where battery energy storage characteristics dominated. The proposed method is verified under different operating conditions. The experimental results show good agreement with the estimation results, which indicates that the proposed method can estimate the SOC of the HyLICs accurately. Full article

As a representative electrochemical energy storage device, supercapacitors (SCs) feature higher energy density than traditional capacitors and better power density and cycle life compared to lithium-ion batteries, which explains why they are extensively applied in the field of energy storage. While the available reviews are mainly concerned with component materials, state estimation, and industrial applications, there is a shortage of understanding of thermal behaviors and thermal management systems of SCs, which makes this review a timely aide for fulfilling this gap. This review introduces the energy storage mechanisms of SCs, followed by descriptions of current investigations of thermal behaviors. This covers the aspects of heat generation rates for electric double-layer capacitors (EDLCs) and hybrid supercapacitors (HSCs), together with reviewing existing experimental methods to measure and estimate heat generation rates, as well as comparative assessments of multiple heat generation rate models and research on thermal runaway. In addition, there are also overviews of current efforts by researchers in air cooling systems, liquid cooling systems, phase change material cooling systems, and heat pipe cooling systems. Finally, an in-depth discussion is provided regarding the challenges and future work directions for SCs in thermal behaviors and thermal management systems. Full article

The lithium-ion battery (LIB) has become the most widely used electrochemical energy storage device due to the advantage of high energy density. However, because of the low rate of Faradaic process to transfer lithium ions (Li⁺), the LIB has the defects of poor power performance and cycle performance, which can be improved by adding capacitor material to the cathode, and the resulting hybrid device is also known as a lithium-ion battery capacitor (LIBC). This review introduces the typical structure and working principle of an LIBC, and it summarizes the recent research developments in advanced LIBCs. An overview of non-lithiated and pre-lithiated anode materials for LIBCs applications is given, and the commonly used pre-lithiation methods for the anodes of LIBCs are present. Capacitor materials added to the cathodes, and suitable separator materials of LIBCs are also reviewed. In addition, the polarization phenomenon, pulsed performance and safety issues of LIBCs and electrode engineering for improving electrochemical performance are systematically analyzed. Finally, the future research and development direction of advanced LIBCs is prospected through the discussion of the existing problems of an LIBC in which the battery material in the composite cathode is LiNi_xCo_yMn_1−x−yO₂ (NCM). Full article