High-power Batteries Research Articles

Solid-State Transformers of Smart High-Power Battery Charger for Electric Vehicles

There is no doubt that society will not turn back: most thermal vehicles will switch to electric ones, not only for cars but also for bigger vehicles. Fast chargers will become more and more essential parts of the global system, they will provide a charge control of batteries and galvanic insulation from the grid. At the present times, compact realizations are based on Solid-State Transformers (SSTs) operating at high frequencies with their well-known advantages and disadvantages, including power limits and reasonably high costs. The authors propose a medium-frequency transformer (MFT) structure using Grain Oriented Electrical Steel (GOES) wound cores and aluminum foil windings. Thanks to this solution, the cost of the device can be reduced. GOES has losses that increase with frequency but decrease with temperature; therefore, the authors propose a transformer structure allowing a hot core inside coils at usual temperatures. This idea is applied to a 400-kW compact battery charger connected to a DC smart grid.

Two-layer cathode architecture for high-energy density and high-power density solid state batteries

Solid state batteries with high-energy density and high-power density require the development of thick and energy dense cathodes. Structured cathode electrodes with a double-layer configuration were enabled using a freeze tape casting technique. A bottom dense layer was utilized to enhance the energy density whereas a top porous layer with vertically aligned walls was utilized to enhance the power density. The porous structure of the power layer was achieved by ice templating this layer on top of the densified energy layer of the cathode. This configuration was found to better utilize the active material of the cathodes and was optimized using numerical simulation and computer modeling. Cells with Li metal anode and LiNi0.6Mn0.2Co0.2O2 (NMC622) at approximately 5 and 20 mg/cm2 were cycled at 70 °C at different C-rates. Poly(ethylene oxide) (PEO) with lithium bis-trifluoromethanesulfonimide (LiTFSI) was used for the catholyte and the solid-state electrolyte. The structured cathodes exhibited more than double capacity values as well as better Coulombic efficiency compared to non-structured (single-layer) thick cathodes. Synchrotron X-ray tomography and scanning electron microscopy were used to characterize the microstructure of the cathodes.

Interphase Design by Localized Super-Concentrated Electrolyte for High-Voltage and High-Power Lithium Metal Batteries

Batteries used in electric aircraft must deliver high-power on take-off and landing, providing in stride the ability to recharge at high voltage to make full use of the cathode capacity. Impedance rise associated with electrode–electrolyte interphases remains problematic with conventional electrolytes, resulting in unacceptable power fade. This is exacerbated when recharging cells at high voltage, which is where interphase generation remains poorly controlled. To address these issues, electrolyte design for high-voltage and high-power batteries should emphasize control over the interphase growth contributing to the impedance rise during charge. To this end, we will describe our recent efforts to alter the activity of various electrolyte components at electrode–electrolyte interfaces, granting access to exquisite control over interphase chemistry. Key to our success is the exploitation of ion clustering in locally super-concentrated electrolytes (LSCEs), which produces aggregates with intrinsically different reactivity than solvated species and from which new interphasial chemistries may be produced in-situ. We find in top-performing compositions that interphase stability is most affected by the activity of ethereal solvents in the formulations, particularly at high voltage, and that it is possible to design additives that suppress solvent activity even up to 4.5 V vs. Li/Li+. Li/NMC811 cells cycled with de-novo designed LSCEs maintain 70% of their initial discharge capacity after 1000 cycles with 4 C discharge rate at charge cut-off voltage of 4.35 V, outperforming most reported electrolytes for Li metal batteries. Furthermore, by taking an informatics approach to interphase characterization, we reveal fundamental patterns of reactivity that inform future selection criteria for advanced battery electrolytes.

Fabrication of Solid-State Li-S Battery Components for Electric Aviation

The development of high-energy, high-safety, and high-power batteries beyond electric automobile requirements is vital for future electric aviation applications. The transition to non-volatile solid-state electrolytes (SSE) promises many advantages over traditional flammable liquid electrolytes, and may also be an enabling technology for next generation chemistries. However, significant manufacturing challenges must be overcome before the adoption of such technology. Electrolytes developed in this study were produced as sulfide-polymer composites with densified thicknesses between 20-30 microns using several processing techniques [1]. Ionic conductivity and lithium metal compatibility for the composites were compared and shown to retain reasonable ionic conductivity with improved flexibility and scalability which identifies a critical path for the production of practical solid-state batteries. Films were produced 10-15 times thinner than comparable bulk cold pressed powder electrolytes and achieved thicknesses comparable to commercial polyolefin separators (25 micron) used in commercial liquid containing lithium-ion cells. Composite conductivities were maintained above 0.2mS/cm, which holds promise for future electric aviation applications. Processing techniques are investigated to further improve electrochemical performance.[1] Donald A. Dornbusch, Rocco P. Viggiano, John W. Connell, Yi Lin, Vadim F. Lvovich. Practical considerations in designing solid state Li-S cells for electric aviation, Electrochimica Acta, 2021, 139406, ISSN 0013-4686, https://doi.org/10.1016/j.electacta.2021.139406.

(Invited) Inductive Effects to Control the Operating Voltage of Fast-Charging Molybdenum Oxide Anodes

Batteries are essential to most modern technologies, as they provide a sustainable alternative to traditional energy sources. One area of active research is in identifying new battery materials made from plentiful elements to produce stable, high power and fast-charging batteries. A candidate for the next-generation anode material is molybdenum oxide, as it shows fast-charging capabilities, stability, and high capacity. The disadvantage of this material is that the expected power is relatively low, as the redox voltage for molybdenum is not optimized to the stability window of the liquid electrolyte. Using the inductive effect as a guiding principle, we suggest lowering the Mo+6/+5 redox voltage by adding a cation to the structure. The structural modification will influence the covalency of the metal-oxygen bond and will therefore allow lower ionization energy (IE) for the d-orbital electrons. To this aim, we compare the electrochemistry of Li2Mo4O13 and MoO3 as well as the IE and the Li diffusivity. The results show that the addition of Li lowers the voltage by 300 mV for Mo+5/+6 compared to MoO3 but does not reduce the Li diffusivity. The change in IE also supports our hypothesis that the Li reduces the polarity of the M-O bond. Additional electrochemical studies indicate limited capacity for Li2Mo4O13 compound, which is related to structural changes after the first lithiation process. Our results demonstrate the utility of exploring new systems with elevated redox voltage to better fit the electrolyte stability window and yield higher power.

Advances in Chelated Metal Electrolyte for Aqueous Flow Batteries

Flow battery electrolyte containing chelated metal ions can support high voltage, high power, and high efficiency battery cycling in pH-neutral conditions. In this talk the coordination behavior and flow battery performance of chelated metal ions including vanadium, chromium, iron, and cerium will be presented. Key to enabling this approach is the fundamental understanding of the coordination properties of the chelating agent to specific metal ions and oxidation states. Techno-economic analyses suggest that the performance advantages of chelation more than offsets the cost of the chelating agents. Finally, strategies towards high concentration (> 2 M) cycling of these electrolytes will be presented, and the implications of energy density on overall system footprint will be discussed.

High C-Rate Dynamic Lithium (de)Insertion Pathway Investigated via Synchrotron-Based Operando XRD and Operando Scanning x-Ray Microscopy

Lithium-ion insertion kinetics fundamentally hinges upon phase transformation behavior during (dis)charging and understanding the rate-dependent kinetics is crucial for the development of high-power batteries. At high c-rates, kinetic hysteresis is amplified and phase evolution becomes heterogeneous and unpredictable. Specifically, discharge becomes more sluggish than charging of most battery electrodes including LiNixMnyCozO2 (NMC) and LiFePO4 (LFP). Here, we developed an operando soft x-ray microscopy to simultaneously observe surface charge transfer and bulk lithium diffusion in facet-controlled individual battery particles over a wide range of cycling rates (0.01 – 10C). Our result unambiguously reveals that dynamic asymmetry between fast charging and discharging originates from auto-inhibitory Li-rich and autocatalytic Li-poor surface domains, respectively. In addition, we developed synchrotron-based operando fast XRD to track phase evolution during fast cycling. We directly observed that sluggish Li diffusion at high Li content induces different phase transformations during charging and discharging, with strong phase separation and homogeneous phase transformation during charging and discharging, respectively. Moreover, by electrochemically manipulating the lithium-ion concentration distribution within NCM particles, phase separation pathway could be redirected to solid-solution kinetics even at 7 C-rate. Our work lays the groundwork for developing high-power applications and ultrafast charging protocols Figure 1

Syringeless electrospun non-woven separator membrane for high-energy and high-power Li-ion battery application

Developing separators to meet the various requirements of next-generation Li-ion batteries (LIBs) is quite challenging because safety issues (good mechanical and thermal properties) and high power and energy density (small thickness and large porosity) exhibit a negative correlation, resulting in a technical contradiction. In general, an electrospun nonwoven membrane is a potential candidate for use in next-generation LIBs, but sufficiently thin electrospun-based nonwoven webs cannot be used as separators owing to their poor mechanical properties and exceedingly large porosity, which fail to prevent dendrite growth. To overcome these shortcomings, we fabricated a composite nonwoven separator using polyvinylidene fluoride (PVDF) and lithium lanthanum zirconium oxide (Li6.4La3Zr2Al0.2O12, LLZO) particles via a syringeless colloidal electrospinning method. To demonstrate the feasibility of our separator membrane for use in high-power and high-energy LIBs, we evaluated the electrochemical performance of an assembled LiNi0.6Co0.2Mn0.2O2 (NCM622)/graphite cell at a high C-rate. The assembled cell containing our separator membrane delivered an outstanding capacity of 115 mAh∙g-1 with a capacity retention of 97% after 100 cycles, even at 3 C. In addition, a Li-metal cell with our PVDF/LLZO separator achieved capacity retention of 86% after 250 cycles at 0.5 C.

Overall upgrading Zn-ion storage capability by engineering N/O co-doped hydrophilic hierarchical porous carbon

The couple of supercapacitors' high power density and batteries' high energy density endows aqueous zinc-ion hybrid supercapacitors (ZIHSCs) a perspective candidate for next-generation energy storage devices. Biomass-derived hierarchical porous carbon with excellent wettability towards aqueous electrolyte is regarded as a promising cathode for ZIHSCs applications. Herein, a N/O co-doped hydrophilic carbon with hierarchical porous architecture is conversed from protein enriched recycled badminton feathers via a facile and scalable strategy. The resultant carbon presents hierarchical porous architecture with high surface area and mesopore-governed pore size distribution, rich dual-doping of N/O heteroatoms and good water wetting behavior. The all-round teamwork of these unique properties provides numerous interfacial active sites plus extra reversible redox reaction for high energy density, and speedy kinetics for high power density. Incredibly, as-assembled ZIHSC device displays an ultrahigh capacity of 225.3 mAh g−1 at 0.1 A g−1 with an appreciable capacity retention of 73.8 mAh g−1 even at a 1000-fold amplified current density, thereby delivering admirable energy and power densities of 201.4 Wh kg−1 and 83.6 kW kg−1. Most satisfyingly, an ultralong cycling life with no loss in capacity is achieved after 40,000 cycles even at 50 A g−1. Therefore, by taking advantage of its intrinsic component, the conversion of biomass waste to high performance carbon-based cathode material holds a broad prospect and practical significance.

Emerging Trends in Thermal Properties of Graphene

We go over the thermal characteristics of graphene, few-layer graphene, and graphene nanoribbons, and we go over some real-world uses for graphene in energy storage and thermal control. The first section of the paper discusses the most recent developments in the graphene thermal area with an emphasis on the experimental and theoretical data on heat conduction in graphene and graphene nanoribbons that have recently been published. In the summary, the effects of the sample's size, shape, quality, strain distribution, isotope composition, and point-defect concentration are discussed. The thermal characteristics of materials used in energy storage that have been increased by graphene are described in the second section of the review. It has been established that the usage of liquid-phase-exfoliated graphene as a filler in phase change materials has promise for the thermal control of high-power density battery parks. The experimental and modelling findings have been disclosed.

Influence of MXene-assisted multifunctional interface on zinc deposition toward highly reversible dendrite-free zinc anodes

The ever-growing demand for safe and renewable energy storage systems has driven the renaissance of aqueous zinc (Zn)-metal batteries (ZMBs). Zn metal has the characteristics of high specific capacity, low cost, environmental friendliness, and intrinsic safety, but severe side reactions and Zn dendrite growth lead to low Coulombic efficiency and short cycle life of Zn metal anode, which restricts the commercial development of rechargeable aqueous ZMBs. Herein, a Ti3C2Tx MXene-derived ZnF2-rich multifunctional interfacial layer is prepared. In this architecture, the as-formed ZnF2-rich layer can redistribute Zn-ion flux on the electrode/electrolyte surface and suppress side reactions. Meanwhile, the results indicate that the ZnF2 can lower the desolvation energy barrier of Zn ions and enhance the Zn-ion transfer kinetics. Accordingly, the Zn@MXene anode delivers a long cycle life over 800 h at the current density of 5.0 mA cm−2 with a capacity of 5.0 mAh cm−2. Surprisingly, the Zn@MXene anode can still achieve dendrite-free Zn deposition for more than 320 h even at the current density of 10.0 mA cm−2 with a capacity of 10.0 mAh cm−2. Additionally, the assembled Zn@MXene//VO2 full-cell exhibits better cycling stability and more excellent rate performance compared to the pristine Zn//VO2 full-cell, implying the potential of this idea to develop high-power rechargeable aqueous Zn-ion batteries.

Preparation and electrochemical performance of FG/SnS2 composite as a cathode material for high power thermal batteries

SnS2 is a promising cathode material for its high specific capacity (1232 mAh/g), but it’s limited to the low decomposition temperature and conductivity as the thermal battery application. Herein, the flaky graphite(FG) coating SnS2 composite (denoted as FG/SnS2) with excellent thermal stability and conductivity was prepared. Then, as a thermal battery cathode material, it presented longer working time at current constant density of 100 mA/cm2, and higher pulse voltage at 2A/cm2 pulse current density than the pure SnS2. Application as the engineering unit thermal battery, its performance of higher working voltage, lower total resistance, and more stable output capacity indicated it can be used for high-power thermal batteries.

Design of phosphorus-doped porous hard carbon/Si anode with enhanced Li-ion kinetics for high-energy and high-power Li-ion batteries

With the rapid progress of portable electronics and electric vehicles, high-energy lithium-ion batteries (LIBs) with fast-charging technology are urgently required. Silicon (Si) is considered as the most promising anode candidate for high-energy LIBs but challenging to large-scale commercialization due to its huge volume change and poor conductivity. To develop high-capacity Si-based anode materials with enhanced lithium-ion diffusion and fast reaction kinetics, we design a novel high-Si-content Si/hard carbon composite via scalable methods. The combination between phosphorus-doped hard carbon with porous structure and uniformly distributed Si nanolayers effectively improve lithium-ion kinetics and mitigate the volume change of Si. As a result, the architecture delivers a reversible capacity of 1124 mAh/g at 0.1C and superior cycling stability with an 87.4% capacity retention after 200 cycles at 1C. The 1.5 A h pouch-type full-cell tests further demonstrate good cycling stability and high rate performance at 4C under an electrode density of 1.6 g cm−3 and areal capacity loading of 3.53 mAh cm−2. This work paves a new way for the rational design of Si-based anode materials for high-energy and high-power LIBs.

Hardware Design for Implementation of Energy Management in a Solar-Interfaced DC Microgrid

The growing power requirement and the limited availability of fossil fuels makes it necessary to use renewable energy resources (RERs) as an alternative. The penetration of renewable sources in the existing power system becomes a big challenge for the safe and reliable operation of the system. Again, the erratic nature of these sources makes it impossible to supply constant power to the consumers. To overcome the intermittency of the environment and to provide constant reliable power to the loads, battery, fuel cell, and supercapacitor like storage devices are required in the system. Here, by considering the complementary characteristics of supercapacitors with high power density (500-5000W/L) and batteries with high energy density(50-80Wh/L), a combination of these two storage devices is used with renewable sources as a hybrid storage system. Hence, a proper power management scheme is necessary to control the power flow in the system and to balance the total power between generation and demand. In this paper, an energy management technique was proposed along with detailed modeling for the experimental setup of the DC microgrid (DCMG). A dSPACE 1103 controller was implemented in the hardware setup. The validation of the proposed energy management scheme and hardware design is done by using both simulation and experimental results.

Magnesium-rare earth intermetallic compounds for high performance high power aqueous Magnesium-Air batteries

Magnesium alloys are light structural materials and promising anode candidates for Mg-air batteries. However, application of Mg-air batteries is limited by poor performance at large current density and severe H2 generation side reactions. In this study, we pioneered magnesium-rare earth Mg3RE (RE=La, Ce, Pr and Nd) intermetallic compounds as anodes to provide higher power density and more stable discharge performance. Especially, Mg3Pr alloy exhibits high discharge voltage of 0.91 V and peak power density of 54.4 mW cm−2 at 60 mA cm−2 with anodic efficiency of 60%, far better than other Mg alloys. We reveal an activation mechanism of Mg3RE-based anodes during discharge, which significantly accelerates mass transfer process as well as enhances discharge activity. The results improve the performance of high-power Mg-air batteries and promote the value-added application of abundant rare earth elements such as Ce and La.

A novel strategy of enhanced thermal performance in air cooled lithium-ion battery by wavy walls

Electric vehicles (EVs) with rechargeable lithium-ion batteries are one of the most appealing choices for electrochemical energy storage to address global energy challenges and environmental concerns caused by rising carbon emissions. However, to maintain the performance and longevity of these high power batteries, a well-planned and effective cooling mechanism is required. Here, a novel air-based battery thermal management system (BTMS) is proposed to realize an improved cooling performance. We examined the thermal performance of an air-cooled lithium-ion battery pack of 3x5 Sony 18650 cells by introducing wavy (undulated) sidewalls for the discharge period of the cells. Influence of air inflow velocity (U0) and number of undulations on wavy wall have been delineated at a discharge rate of 2C and 3C. As obvious, the cooling improves with the increasing U0. Interestingly, a significant reduction (∼ 8-10 K) in the average and maximum cell temperature was seen simply by creating an optimal number of undulations on the walls as compared to the results obtained from straight walls. The highest cooling performance was observed when the undulations form a trough above the cells, however, the highest pressure drop was experienced in such cases. A trade-off between the cooling enhancement and power requirement (∼ pressure drop) has been presented by a performance plot. Finally, the efficacy of system was ensured by changing the number of rows and columns of the cell arrangement in the battery pack. An enhanced heat dissipation and thermal uniformity was seen in all the cases when wall undulations are present.

A novel calcination method towards layered Ni-rich cathode with enhanced electrochemical performances and regulated oxygen vacancies

Layered Ni-rich cathodes that simultaneously possess high-energy density with robust cyclic performances are highly desired to the application of high-power lithium-ion battery. However, the formation of Li+/Ni2+ cation mixing and oxygen vacancies is an inevitable occurrence that causes poor crystal structure, leading to detrimental effects on electrochemical performance during traditional high-temperature calcination. Herein, the LiNi0.9Co0.05Mn0.05O2 cathode material with enhanced electrochemical performances was prepared via a novel calcination method replacing LiOH of Li2O2 (NCM-O2), which could effectively solve the reduction of Ni3+ and the information of oxygen vacancies and Li+/Ni2+ cations mixing. The effect of Li2O2 on the preparation of LiNi0.9Co0.05Mn0.05O2 was systematically investigated. The novel calcination method increased the oxygen pressurization and changed the redox conversion equation, thus reducing Li+/Ni2+ cation mixing (3.33% to 2.12%) and regulating the formation of oxygen vacancies (9.44% to 6.39%). As a consequence, the NCM-O2 based battery exhibits remarkable cycling stability from room temperature (RT) to 50 °C in a voltage range of 2.8–4.3 V. As-assembled Li/NCM-O2 battery shows superior cyclability of 177.9 mAh g−1 after 100 cycles at 1C under RT with a cycle retention of 95.2%. As such, our work of novel calcination method opens a simple and effectively route to develop layered Ni-rich cathodes with enhanced electrochemical performances for high-power lithium-ions batteries.

Cyber-Physical Cloud Battery Management Systems: Review of Security Aspects

Battery management systems (BMSs) are critical to ensure the efficiency and safety of high-power battery energy storage systems (BESSs) in vehicular and stationary applications. Recently, the proliferation of battery big data and cloud computing advancements has led to the development of a new generation of BMSs, named Cloud BMS (CBMS), aiming to improve the performance and safety of BESSs. The CBMS is a cyber-physical system with connectivity between the physical BMS and a cloud-based virtual BMS, which is realized through a communication channel such as Internet of Things. Compared to the traditional BMS, the CBMS offers significantly higher computational resources, leveraging the implementation of advanced digital twin models and best-in-class algorithms in the BMS software, which will provide superior performances. However, as for any other CPS, the CBMS creates vulnerabilities against cyberattacks and if not properly secured, could end up damaging the BESS and/or causing dangerous, expensive, and life-threatening situations. Cybersecurity of the CBMSs has thus become a trending topic and several works have been published in this area in recent years. This paper conducts a scoping review to address different topics related to BMS cybersecurity. The CBMS architecture is presented, and the potential cyberattack surfaces are identified. Different possible attack scenarios, including attack points, attack types, and their impact at the component level (BMS and BESS) and system level (vehicle or grid), are discussed. In addition, the paper provides a review of potential countermeasures to protect the CBMS against cyberattacks. The paper also includes a review of the applicable standards and regulations that relate to this trending topic. Finally, based on the reviewed gaps, potential future research domains on BMS cybersecurity topics are identified and presented at the end of the paper.

Application of Diluted Electrode Method to Sodium-ion Insertion into Hard Carbon Electrode

Herein, the diluted-electrode method is applied to a hard carbon (HC) electrode to estimate sodium-ion (Na+) insertion kinetics. As metallic nickel (Ni) particles do not accommodate Na+ ions in the potential range of 0–2.0 V vs. Na+/Na, the HC powder electrode is diluted by adding inert Ni particles, enabling the adjustment of the HC concentration while maintaining the composite electrode structure. By examining the rate capabilities of the HC electrodes with different dilutions, we confirm that the Na+ insertion rate for the highly diluted electrode is 10 times higher than that for the undiluted electrode. These improved kinetics can be attributed to the alleviation of Na+ depletion, which results in insignificant concentration polarization under dilute conditions. For a highly diluted electrode, the Na+ insertion kinetics must be controlled by the Na+ mobility in the HC particles and across the HC/electrolyte interface. Therefore, our study reveals that the inherent kinetics of Na+ insertion into HC are very high and provides a basis for developing high-power Na-ion batteries.

A Review of Advanced Cooling Strategies for Battery Thermal Management Systems in Electric Vehicles

Electric vehicles (EVs) offer a potential solution to face the global energy crisis and climate change issues in the transportation sector. Currently, lithium-ion (Li-ion) batteries have gained popularity as a source of energy in EVs, owing to several benefits including higher power density. To compete with internal combustion (IC) engine vehicles, the capacity of Li-ion batteries is continuously increasing to improve the efficiency and reliability of EVs. The performance characteristics and safe operations of Li-ion batteries depend on their operating temperature which demands the effective thermal management of Li-ion batteries. The commercially employed cooling strategies have several obstructions to enable the desired thermal management of high-power density batteries with allowable maximum temperature and symmetrical temperature distribution. The efforts are striving in the direction of searching for advanced cooling strategies which could eliminate the limitations of current cooling strategies and be employed in next-generation battery thermal management systems. The present review summarizes numerous research studies that explore advanced cooling strategies for battery thermal management in EVs. Research studies on phase change material cooling and direct liquid cooling for battery thermal management are comprehensively reviewed over the time period of 2018–2023. This review discusses the various experimental and numerical works executed to date on battery thermal management based on the aforementioned cooling strategies. Considering the practical feasibility and drawbacks of phase change material cooling, the focus of the present review is tilted toward the explanation of current research works on direct liquid cooling as an emerging battery thermal management technique. Direct liquid cooling has the potential to achieve the desired battery performance under normal as well as extreme operating conditions. However, extensive research still needs to be executed to commercialize direct liquid cooling as an advanced battery thermal management technique in EVs. The present review would be referred to as one that gives concrete direction in the search for a suitable advanced cooling strategy for battery thermal management in the next generation of EVs.