High Power Density Batteries Research Articles

High power density battery chargers with fast-charging utilizing heat storage

While wide bandgap semiconductor technology, such as gallium nitride, has considerably enhanced power density in mobile battery charger applications, the development of smaller, cost- and resource-effective systems is hindered by thermal constraints arising from miniaturized components and compact housings. This work proposes a transient thermal management system that dynamically adjusts converter output power according to thermal boundaries, utilizing latent and sensible heat storage to enable an initial boosted performance. An analytical and numerical sensitivity analysis of power density limits was conducted to evaluate the impact of thermal and electrical boundary conditions. A 40W hardware prototype of a quasi-resonant flyback converter with transient thermal management was realized using epoxy resin and phase change material filling. The findings show a 40% higher effective power density when charging a conventional 50Wh laptop battery, all within the same thermal boundaries as common operation at constant output power, with a power density measurement accuracy of 5.2%. The system was implemented using PI controller for inner component and surface temperature control. This novel approach to fast-charging highlights the optimization potential of current systems through converter heat storage utilization and provides valuable insights, including analytical and numerical models, for developing chargers capable of overcoming thermal barriers.

The decisive role of electrostatic interactions in transport mode and phase segregation of lithium ions in LiFePO4.

Understanding the mechanism of slow lithium ion (Li+) transport kinetics in LiFePO4 is not only practically important for high power density batteries but also fundamentally significant as a prototypical ion-coupled electron transfer process. Substantial evidence has shown that the slow ion transport kinetics originates from the coupled transfer between electrons and ions and the phase segregation of Li+. Combining a model Hamiltonian analysis and DFT calculations, we reveal that electrostatic interactions play a decisive role in coupled charge transfer and Li+ segregation. The obtained potential energy surfaces prove that ion-electron coupled transfer is the optimal reaction pathway due to electrostatic attractions between Li+ and e- (Fe2+), while prohibitively large energy barriers are required for separate electron tunneling or ion hopping to overcome the electrostatic energy between the Li+-e- (Fe2+) pair. The model reveals that Li+-Li+ repulsive interaction in the [010] transport channels together with Li+-e- (Fe2+)-Li+ attractive interaction along the [100] direction cause the phase segregation of Li+. It explains why the thermodynamically stable phase interface between Li-rich and Li-poor phases in LiFePO4 is perpendicular to [010] channels.

Mineral Oil Immersion Cooling of Lithium-Ion Batteries: An Experimental Investigation

Abstract Effective thermal management of high power density batteries is essential for battery performance, life, and safety. This paper experimentally investigates direct mineral oil jet impingement cooling of the lithium-ion (Li-ion) battery pack. For the first time, experimental results of mineral oil-based cooling of batteries are reported. Both charging and discharging characteristics on temperature uniformity and of a Li-ion pack are considered. Temperature uniformity among cells, as well as within individual cells, is experimentally measured. As a baseline, cooling of the battery pack by free-convective airflow is also reported. Two different jetting configurations: (a) submerged jet and (b) direct-jet impingement are considered. For the highest charge-discharge rates considered (2C charge and 3C discharge), mineral oil nearly maintains uniform skin temperature among the cells (less than 1 °C) as well as within the cell. Based on the results obtained, modular jet oil cooling is an excellent cooling solution of lithium-ion packs applicable to stationary electrical storage and transportation applications.

Improved Electrochemical Properties of Li4Ti5O12 Nanopowders (NPs) via Addition of LiAlO2 and Li6SiON Polymer Electrolytes, Derived from Agricultural Waste

Li4Ti5O12 (LTO) has received considerable interest as an alternate anode material for high power density batteries for large scale applications. However, LTO suffers from poor Li+ diffusivity and poor electronic conductivity, resulting in capacity loss and poor rate performance. Here we demonstrate a facile synthesis of LTO NPs using liquid-feed flame spray pyrolysis (LF-FSP) which provides high surface area (∼38 m2/g) spinel structure LTO NPs with average particle sizes (APSs) of 45 ± 0.3 nm. Pristine LTO-Li half-cells exhibit reversible capacity of 70 mAh/g at 10 C. In this study, we show that mixing LiAlO2 NPs (5 wt %) and Li6SiON polymer precursor (10 wt %) with pristine LTO via ball-milling and ultrasonication followed by tape casting enhances the LTO rate performance providing reversible capacity of ∼217 mAh/g at 5 C over 500 cycles. The Li6SiON polymer electrolyte is synthesized from rice hull ash (RHA), an agricultural waste, providing a green synthetic approach to electrode coating materials. CV and EIS studies indicate that adding the solid and polymer electrolytes reduces charge-transfer resistance and electrode polarization, enhancing both reversibility and the LTO Li+ diffusion coefficient from 4.6 × 10–14 to 2.7 × 10–12 cm2/s.

Decentralised control strategy for hybrid battery energy storage system with considering dynamical state‐of‐charge regulation

Hybrid battery energy storage system (HBESS) consists of high power density battery and high energy density battery will have a bright future in special isolated DC microgrid conditions such as the all-electric ships and all-electric airplanes, which have strict limitation on storage capacity and size. In this study, a new decentralised control strategy based on mixed droop is proposed to HBESSs with considering the batteries. In decentralised control strategy, conventional V–I droop controller is utilised to high energy density battery to mainly supply the steady power, I–V droop controller is utilised to high power density battery to respond to power change and supply a few steady power. In addition, dynamical state-of-charge (SoC) regulation algorithm is utilised to reassign the battery power according to their own SoC. The power coordination of the high energy density batteries and high discharge rate batteries is achieved by adjusting the values virtual impedance and reference input voltage. Case study shows that the proposed control strategy is flexible and efficient.

Modulation of Cation Diffusion by Reversible Supramolecular Assemblies in Ionic Liquid-Based Nanocomposites.

Ionic liquid (IL) properties, such as high ionic conductivity under ambient conditions combined with nontoxicity and nonflammability, make them important materials for future technologies. Despite high ion conductivity desired for battery applications, cation transport numbers in ILs are not sufficient enough to attain high power density batteries. Thus, developing novel approaches directed toward improvement of cation transport properties is required for the application of ILs in energy-storing devices. In this effort, we used various experimental techniques to demonstrate that the strategy of mixing ILs with ultrasmall (1.8 nm) nanoparticles (NPs) resulted in melt-processable composites with improved transport numbers for cations at room temperature. This significant enhancement in the transport number was attributed to the specific chemistry of NPs exhibiting a weaker cation and stronger anion coordination at ambient temperature. At high temperature, significantly weakened NP–anion associations promoted a liquid-like behavior of composites, highlighting the melt-processability of these composites. These results show that designing a reversible dynamic noncovalent NP–anion association controlled by the temperature may constitute an effective strategy to control ion diffusion. Our studies provide fundamental insights into mechanisms driving the charge transport and offer practical guidance for the design of melt-processable composites with an improved cation transport number under ambient conditions.

A Cost‐Effective Mixed Matrix Polyethylene Porous Membrane for Long‐Cycle High Power Density Alkaline Zinc‐Based Flow Batteries

AbstractAlkaline zinc‐based flow batteries (ZFBs) have received considerable interest for renewable energy storage due to their attractive features of low cost and high energy density. However, a membrane with high stability, high selectivity, and high ion conductivity is in urgent need. Herein, an economical mixed matrix membrane with highly anti‐alkali microporous hollow spheres (denoted as DM‐HM) is developed in this work. With excellent chemical and mechanical stability, DM‐HM can achieve a high area capacity of 100 mA h cm−2 for carbon felt (CF)||Zn@CF symmetrical flow battery, and thereby exhibits 500 stable cycles with a coulombic efficiency of 98.6% and an energy efficiency of 88.3% at 80 mA cm−2 for alkaline zinc–iron flow battery. Additionally, with 44 wt% of hollow spheres inside matrix, DM‐HM can dramatically shorten the ion transport pathway and results in a very high power density battery. A kilowatt stack assembled with DM‐HM shows a very impressive performance, further confirming the practicability of this scalable mixed matrix membrane for alkaline ZFBs.

Investigation of carbon-decorated LiVPO4F nanoparticles as cathode for lithium-ion batteries with enhanced rate capability and cyclic performance

Polyanion-type LiVPO4F has been regarded as a potential candidate of cathode material for lithium-ion batteries due to its high working voltage, excellent thermal stability and good safety. However, the pure LiVPO4F has a low electronic conductivity of 10−11 S cm−1, which greatly limits its application in high-power density batteries. In this research, the core-shell carbon-coated LiVPO4F composite is prepared using a facile sol-gel method followed by a solid-state reaction. Owing to the synergistic effects rendered by the LiVPO4F nanoparticles and conductive carbon coating, the as-prepared composite exhibits high reversible capacity (147.9 mAh g−1 at 0.1 C), excellent rate capability (121.2 mAh g−1 at 5 C) and stable cyclic performance (94% capacity retention after 200 cycles at 2 C). These results reveal that the carbon-coated LiVPO4F material is a promising cathode material for high-power lithium-ion batteries.

Design and Implementation of Assisting Converter-Based Integrated Battery Management System for Electromobility Applications

This paper presents a high power density battery management system for electromobility applications that integrates voltage step-up and cell balancing functions inside a single converter topology. The presented system is based on assisting conversion concept, implemented with multiple dual-active bridge (DAB) converter modules. The assisting conversion, where the converter is only processing a portion of the output power proportional to the voltage difference between the battery pack and the output of the converter, allows for the use of a smaller converter than those of conventional systems. Also, at the system level, this type of conversion results in a higher power processing efficiency. The modular structure of the converter provides multiple connections to battery cells and allows on-line cell balancing during standstill, charging, and discharging of the battery pack. The operation of the system is regulated by a practical digital controller that performs cell balancing and, at the same time, regulates the output voltage. Experimental results obtained with a 24–48 V, 200-W, 100-KHz converter for small scooters demonstrate that the assisting converter is capable of providing the two previously mentioned functions while having a smaller volume and better power processing efficiency than both the conventional DAB and boost-based solutions. The assisting DAB converter runs at a peak efficiency of a 95.4% and processes only a maximum of a 66% of the output power.

High Power Density Battery Charger for Plug-In Micro EV

Household distributed power systems that the renewable energy such as the PV and the wind power are introduced as energy sources are expected to spread in the future as efforts for global decarbonization. EV has already been recognized the role as a battery for the energy management of the household distributed power system. The Micro EV which is a kind of EV requires frequent charging from a household AC outlet due to its small capacity, so it is necessary to suppress the harmonics of the AC power source and charge the battery at an appropriate power factor. For this reason, the charger of micro EV generally has two stages of a converter which performs input control with a PFC (power factor correction) function and a converter which performs charge control. However, the reduction in size and the weight is an important factor for the traveling performance of EVs, and the miniaturization and the weight reduction are also required for the onboard charger. Therefore, in this paper, a method to control the input current and charge control to the battery with a single converter is proposed. By using the proposed single-stage converter, it is possible to dramatically improve the energy density and the power conversion efficiency. Moreover, it is confirmed that the proposed circuit can cope with dc input from the dc bus, and is also an effective application in the dc bus based household distributed power system which is expected to spread in the future.

Synthesis and electrochemical performance of vertical carbon nanotubes on few-layer graphene as an anode material for Li-ion batteries

Bulk graphite is widely used in today's Li-ion batteries as an anode material due to its high cycling stability. However, graphite's low capacity and rate capability prevent its application in high power density batteries. Here, a nanostructured carbon, consisting of vertical carbon nanotubes on few-layer graphene, has been synthesized and tested as an anode material for high capacity Li-ion batteries. In this synthesis, a simple hydrothermal method was used to assemble homogeneous distributed Fe2O3 nanoparticles on few-layer graphene based on van der Waals interaction, and these were then used as a catalyst to grow carbon nanotubes further by means of a chemical vapor deposition method. The electrochemical properties of the nanocomposites were measured. A reversible capacity of 525 mAh g−1 after 1000 cycles at 500 mA g−1 with Coulombic efficiency in excess of 98% was accomplished. Voids between vertical carbon nanotubes provide a short diffusion path for both electron and Li-ion, and the defects in carbon nanotubes provide more storage sites for lithium. Three kinds of nanocomposites with different carbon nanotube diameters were synthesized and characterized. The influence of the carbon nanotube diameter and morphology on the lithium storage properties of these nanocomposites was also studied.

Remarkably stable high power Li-ion battery anodes based on vertically arranged multilayered-graphene

Electrodes with novel architectures may enable the construction of high power density batteries with ultrafast charge/discharge performances, which are fundamental for todays power tools, medical devices and transportation systems. Hereby, we demonstrate the application of vertically arranged multilayered-graphene, namely carbon nanowalls (CNW), as a potential high power anode to be used in Li-ion secondary batteries. CNWs are deposited onto Cu foils using microwave plasma enhanced chemical vapor deposition (MPE-CVD) technique. MPE-CVD is a simple and rapid technique, which is effectively proven to produce self-standing layered anodes by single step processing. The direct deposition over Cu avoids the addition of foreign ingredients such as binders and conductive agents. This opens up the possibility to reduce the number of processing steps and processing time, which are key aspects when upscaling is sought. The superior cycling behaviour of the newly elaborated CNWs is demonstrated in lab-scale Li-metal and Li-ion cells (LiFePO4 cathode) capable of very stable and prolonged reversible cycling with excellent durability (>1000 cycles), good specific capacity and capacity retention when subjected to ultrafast current regimes.

Lithium Surface Modification for Enhanced Cycle Life and Safety of Lithium Batteries

Lithium (Li) metal is an ideal anode material for rechargeable batteries due to its extremely high theoretical specific capacity (3860 mAh/g), low density (0.59 g/cm3) and the lowest negative electrochemical potential (-3.04 V vs. the standard hydrogen electrode, SHE). Li battery based on Li metal anode is expected to have an order of magnitude higher energy density than today's Li-ion battery. This will enhance energy and power capability of battery devices used in portable electronics, hybrid electric cars, aerospace, telecommunication, military, etc.). The Li metal battery will fulfill the high energy demand that cannot be met through the current Li-ion batteries (e.g. all electric transportation or many other applications which require light weight, high energy density, high power density batteries with small battery footprint and safest). But, to date, uncontrolled dendritic Li growth and limited Coulombic efficiency (CE) during Li deposition/stripping of a bulk Li anode, are the main reason behind low cycle life, which has limited their practical applications. Furthermore, the rate of dendrite growth gets amplified when the cell is cycled at high charge-discharge current density, high charge voltage, and high areal discharge. Increasing anode surface area would reduce the effective charge/discharge current. Additionally, thin films and high surface area Li anodes exhibit high ionic and electronic conductivity contributing to the high efficiency of the current collection required for high capacity battery. Although low CE can be partially compensated by an excess amount of Li (at the expense of lower useable Li energy), fire and other hazards associated with the dendrite growth have limited the development of rechargeable Li metal batteries. Most approaches to dendrite prevention focus on improving the stability and uniformity of the solid-electrolyte interface (SEI) on the bulk Li surface by adjusting electrolyte components and optimizing SEI formation additives. It is very difficult to achieve sufficient passivation on Li electrode due to the thermodynamic instability of Li with electrolytes [1,2]. As an alternative, various mechanical barriers have been proposed to block dendrite penetration [3]. These approaches rely on a strong mechanical barrier provided by an SEI film or a separator to suppress Li dendrite penetration but do not change the fundamental, self-amplifying behavior of the dendrite growth. Also, it is hard to find a mechanical barrier material with required shear modulus (required > 109 Pa) with desired conductivity. In other words, these methods did not prevent Li dendrites from growing during long-term cycling at high charge-discharge current density, high charge voltage, and high areal discharge, or hardly improved the CE and safety in Li deposition/stripping which is not suitable for practical rechargeable Li batteries [1]. We have developed a novel ionic-electronic-mechanical membrane (an artificial SEI), which allows long-term Li cycleability and improved safety by reducing dendrite formation. The new artificial SEI is comprised of three different materials to fulfill the desired SEI criteria such as: (a) facilitate uniform Li ion dispersion and deposition on entire Li surface, (b) desired SEI conductivity (c) mechanical separation of Li and electrolyte and flexibility to contain anode volume change during Li stripping and deposition. The combined effect of the invented SEI result into more than 300% increase in number of cycles and 3-4 times increase in usable Li energy density (i.e. high Coulombic efficiency (CE)) of a wet battery composed of protected Li metal anode, liquid electrolyte (e.g. lithium hexafluoro arsenate, LiAsF6) and Li-ion cathode (e.g. lithium cobalt oxide, LCO) for the advancement of a battery beyond the state-of-the-art Li-ion battery. The added advantage of the invented SEI is improved safety due to suppression of dendrite growth by mechanically strong/flexible SEI and controlled, uniform deposition/stripping of Li from Li anode surface. The protected Li anode may be incorporated into wet cell batteries or solid state batteries having transition metal oxide cathodes (more specifically the state-of-the-art Li-ion cathodes) or Sulfur cathode (Li-S battery) or Oxygen cathode (Li-O2 battery). Moreover, similar methodologies can be applied to other rechargeable metal anodes (Na, Al, Mg, etc.) used in batteries.

A novel co-doped LiFePO4/C cathode material, modified for enhanced high power density battery applications

Crystalline LiFePO4/C and co-doped LiFe1−x−yNixCoyPO4/C (x=0.00–0.04; y=0.00–0.04) nano-composite phases were synthesized by a simple high-temperature solid-state method. Structural characterization of samples conducted through X-ray diffraction, indicates highly crystallized olivine-related structure. Moreover, it implies that the Ni and Co co-doping on one side does not weaken the olivine structure of LiFePO4 and on the other side can further stabilize the crystal structure. Scanning Electron Microscopy (SEM) applied as morphological evaluation tool and depicted uniform grain distribution, smooth particles surface, and particles within nanometre range dimensions. Electrochemical performance characterization of the samples conducted by charge/discharge tests, illustrated that the Ni and Co co-doping improves cycling and high-rate capability of the LiFePO4/C. Especially, the LiFe0.98Ni0.01Co0.01PO4/C showed the best cycle stability and rate capability among all of the samples, reaching 93% of theoretical discharge capacity (∼170mAh/g). Thereby, excellent cycle performance and capacity retention through wide discharge rates (C/10–10C) would make this cathode material a promising candidate for large-scale Li-ion/Polymer battery applications; such as PHEV, EV, grid storage and other energy storage systems.

ChemInform Abstract: Advances in Spinel Li4Ti5O12 Anode Materials for Lithium‐Ion Batteries

AbstractReview: 243 refs.

Power Management of Supercapacitors using Multi boost and Full Bridge Converters Used in Electric / Hybrid Electric Vehicle

The Hybrid electric vehicle (HEV) has become one of the most promising vehicles in the automobile industry due to its energy saving ability and low emission of harmful pollutants. Battery management system, which has acceptable life cycle, remains the major roadblock to large-scale production of Electric vehicles and Hybrid electric vehicles, which consists of high power density batteries. In the last few years the pollution problems and the increase of the cost of fossil energy (oil, gas) have become planetary problems. The car manufacturers started to react to the urban pollution problems in nineties by commercializing the electric vehicle. But the battery weight and cost problems were not solved. The batteries must provide energy and peaks power during the transient states. These conditions are severe for the batteries. To decrease these severe conditions, the super capacitors and batteries associate with a good power management present a promising solution. Simulink, a model is a collection of blocks which, in general, represents a system. This paper emphasis more on the management of the energy provided by super capacitor Packs. Each super capacitors module is made of 108 cells with a maximum voltage of 270V. The multi boost and multi full bridge converter topologies are tested to define the best topology for the embarked power management.. The experimental and simulated results validate the proposed two converter topologies presented in this paper.

Further studies of the anodic dissolution in sodium chloride electrolyte of aluminium alloys containing tin and gallium

Abstract As part of a programme to develop a high power density, Al/air battery with a NaCl brine electrolyte, the high rate dissolution of an aluminium alloy containing tin and gallium was investigated in a small volume cell. The objective was to define the factors that limit aluminium dissolution in condition that mimic a high power density battery. In a cell with a large ratio of aluminium alloy to electrolyte, over a range of current densities the extent of dissolution was limited to ∼1000 C cm −2 of anode surface by a thick layer of loosely bound, crystalline deposit on the Al alloy anode formed by precipitation from solution. This leads to a large increase in impedance and acts as a barrier to transport of ions.

Preparation of the electrochemically formed spinel-lithium manganese oxides

Electrochemically formed spinel-lithium manganese oxides were synthesized from manganese hydroxides prepared by a cathodic electrochemical precipitation from various concentrations of manganese nitrate solutions. Two types of manganese hydroxides were formed from diluted and concentrated Mn(NO 3) 2 aqueous solutions. Uniform and equi-sized disk shaped Mn(OH) 2 crystals of 0.2–5 μm in diameter were obtained on a Pt substrate after the electrochemical precipitation from lower concentration of ranging from 2 mmol dm −3 to 2 mol dm −3 Mn(NO 3) 2 aq., while the grass blade-like precipitate which is ascribed to manganese hydroxide with 20–80 μm long and 1–5 μm wide were formed from concentrated Mn(NO 3) 2 aq. Both manganese hydroxides gave the electrochemically formed spinel-LiMn 2O 4 onto a Pt sheet, which is ready for electrochemical measurement, after calcination of the Li incorporated precipitate at 750 °C without any additives. While the shape and size of the secondary particle frameworks (aggregates) of the electrochemically formed spinel-LiMn 2O 4 can be controlled by the electrolysis conditions, the nanostructured primary crystals of 200 nm in diameter were obtained in all cases except that the fiber-like nanostructured spinel-LiMn 2O 4 crystals with 200 nm in diameter were obtained from concentrated Mn(NO 3) 2 aq. Though these two types of electrochemically formed spinel-LiMn 2O 4 showed well-shaped CVs even in higher scan rates, it would be suitable for high power density battery applications. These behaviors are assumed to be ascribed to the crystal size and shape of the processed spinel-LiMn 2O 4.

Schweizerisches Energieforschungsprogramm Elektrochemie

The need of advanced power sources especially for electric vehicle and load leveling applications motivated the Swiss government to promote a research program in electrochemistry. This program concentrates on research of electrode and electrolyte materials which are of interest for the development of new energy-storage and conversion devices such as advanced batteries, fuel cells, and electrolysers. The program involves researchers from different disciplines and institutes. Material research, electrochemical engineering, and system modeling are the main topics of the program. The material research is concentrating on electrode materials with high energy content like Li, Al, Mg, Ca, and insertion electrodes. Important research topics are also conducting polymers, redox polymers, and polyelectrolytes or solid electrolytes. In a later stage, the research achievements should be used to develop high power density batteries and fuel cells.

Testing Batteries for Vehicular Applications: III . Selection and Characterization of a Power Battery

The problem was to find an acceptable “power” battery (i.e., a high power density battery to deliver short time acceleration pulses) for an electric commuter vehicle concept powered by a dual battery system. A number of batteries were tested, both Pb‐acid and Ni‐Cd. The best battery was a Ni‐Cd aircraft starting battery. It could deliver 14 consecutive 1900W, 10 sec acceleration power pulses. It was calculated that about 180 lb of battery would be required for the particular power plant design envisioned. The high cost and scarcity of Cd militated against the use of a Ni‐Cd battery. The next best candidate was a Pb‐acid aircraft starting battery designed for high current drains for short time periods. It, too, delivered 14 consecutive 1900W, 10 sec pulses. In addition, it had sufficient energy capacity to provide some low speed range in the event of failure of the “base‐load” energy battery. It had a power density of 70 W/lb at an energy density of 2 Whr/lb. About 270 lb of this battery would be required for the “power” battery pack. A Delco‐Remy 2HN‐11A military battery was tested to yield design data for the power plant. From these data, a battery was designed which would fit into an available lightweight container. Prior to this, a 2HN‐11A modified battery was tested to confirm the design. Test results confirmed the designed capacities.Several of the design batteries were built. Each consisted of seven cells containing 11 plates per cell. One of the batteries was tested. It delivered 15 consecutive 2500W acceleration power pulses to 10.5V. It weighed 32 lb; hence, the entire power pack would weigh 256 lb. Since the 11‐plate cell performed so well, it was hoped that a 9‐plate cell might just deliver adequate power. A 27 lb weight reduction would be realized. However, it could not deliver adequate power when tested. Nothing could be obtained at 2500W. The voltage fell immediately below 10.5. In fact, only 1.8 min were obtained at 1900W.