Local Heat Generation Research Articles

Highly Reproducible Hyperthermia Response in Water, Agar, and Cellular Environment by Discretely PEGylated Magnetite Nanoparticles.

Local heat generation from magnetic nanoparticles (MNPs) exposed to alternating magnetic fields can revolutionize cancer treatment. However, the application of MNPs as anticancer agents is limited by serious drawbacks. Foremost among these are the fast uptake and biodegradation of MNPs by cells and the unpredictable magnetic behavior of the MNPs when they accumulate within or around cells and tissues. In fact, several studies have reported that the heating power of MNPs is severely reduced in the cellular environment, probably due to a combination of increased viscosity and strong NP agglomeration. Herein, we present an optimized protocol to coat magnetite (Fe3O4) NPs larger than 20 nm (FM-NPs) with high molecular weight PEG molecules that avoid collective coatings, prevent the formation of large clusters of NPs and keep constant their high heating performance in environments with very different ionic strengths and viscosities (distilled water, physiological solutions, agar and cell culture media). The great reproducibility and reliability of the heating capacity of this FM-NP@PEG system in such different environments has been confirmed by AC magnetometry and by more conventional calorimetric measurements. The explanation of this behavior has been shown to lie in preserving as much as possible the magnetic single domain-type behavior of nearly isolated NPs. In vitro endocytosis experiments in a colon cancer-derived cell line indicate that FM-NP@PEG formulations with PEGs of higher molecular weight (20 kDa) are more resistant to endocytosis than formulations with smaller PEGs (5 kDa), showing quite large uptake mean-life (τ > 5 h) in comparison with other NP systems. The in vitro magnetic hyperthermia was performed at 21 mT and 650 kHz during 1 h in a pre-endocytosis stage and complete cell death was achieved 48 h posthyperthermia. These optimal FM-NP@PEG formulations with high resistance to endocytosis and predictable magnetic response will aid the progress and accuracy of the emerging era of theranostics.

Photothermal conversion of Bi2Se3 nanosheets and efficient steam generation by capillary siphoning

Local heating under light illumination provides a noncontact way to present an enormous superiority for minimum heat dissipation compared with other cases, such as floating on the surface of water. The highly-effective broadband absorption of Bi2Se3 covering both infrared and visible wavelength range can result in a high efficiency of 68% at 1 W/cm2 light illumination. The device possesses the barrier-free path to ensure the generated steam fast escape from the water surface also achieves the local heat generation and straightway wicks the adequate micro-flow to hot zone. The highlighted advantage of our design is that the efficiency is scarcely susceptible even the uninterrupted water flow, unlike the floated film, the heat dissipation is bound to generate due to the heat exchange between the heated and unheated water. The trade-off between temperature and water supplement should be ensured under the large heat generation and maintain an ideal evaporation rate for solar desalinate application.

Simulating Electrochemical Behaviour of Lithium-Ion Cylindrical Cells Using Two-Dimensional Physics-Based Model

High energy storage density and energy conversion efficiency, rechargeability and zero tailpipe emissions of lithium-ion batteries make them an attractive choice for powering automobiles. However, significant research and improvement are still required to make these batteries comparable with the convenience associated with the use of fossil fuels. One of the major concerns associated with batteries in electric vehicles (EVs) is of safety due to the high current requirements. In this regard, battery pack designs can benefit tremendously by simulating adverse thermo-electrochemical scenarios. Due to the coupled nature of the electrochemical behaviour of the cell on its temperature distribution, the knowledge of temperature distribution and heat generation in constituting cells is required to predict the cell charge-discharge behaviour, local hot-spots formed within the cell and their influence on thermal runaways during pack operation. Though many attempts were made in the past towards this goal, however, several assumptions were used to simplify the model for cylindrical cells. Lumped thermal models with constant temperature were used to determine the cell temperature directly using experimental data [1] or using pseudo-2D model [2,3] on unwounded cells [4]. Heat generation was homogenized in the energy balance [5] and used along with experimental data for computation [6]. The lack of spatial-dependence in such models is not a good representation of physics expected in large format cylindrical cells due to their low effective transport and thermal properties, and the highly non-homogeneous material used to fabricate these cells.Some models that consider spatial dependence of physics employ this either in one-dimensional radial direction [7], two-dimensional in transverse section [8], or three-dimensional approximation using two-dimensional resistor circuits for current collectors with non-linear one-dimensional resistors between adjacent current collector nodes [9]. For a proper understanding of local heat generation, the three-dimensional, highly local, and coupled nature of thermo-electrochemical behaviour needs to be taken into account in the model. In a step towards this goal, the present work aims at developing a two-dimensional physics-based thermo-electrochemical model for cylindrical cells. The differential-algebraic governing equations have been solved implicitly with the non-linear term in each linearized for one variable at a time using the Taylor series expansion. This approximation method ensures second-order accuracy for the linearized variable being computed while the non-linearity is retained for the other unknown variables. A variable time step solver based on the stability of the output voltage profile enables improved computational speed. A second-order differencing in space and backward differencing in time have been implemented for discretizing the partial differential equations into algebraic equations. The Gauss-Seidel method is employed to iterate for the variables at each time step. This discretization technique has been validated (Fig.1a) over a range of C-rates (up to 6C) against an available solver [10]. Subsequently, the method is adapted for polar coordinates to simulate the two-dimensional cross-section of cylindrical cells. The discretization of the geometry, as shown in Fig.1b, has been done ensuring nodes on all the boundaries separating various domains along the windings. The different domains within the coil have been discretized using Archimedean spirals with nodes at uniformly distributed angular coordinate. The simulation results will be validated using data obtained from cycling of Samsung INR18650-29E lithium-ion cells on a high-current cell cycler in controlled temperature environment. In the future, the coupling of the electrochemical and thermal models for the cylindrical cell geometry will also be attempted.

Designing the Heat Merit Order to determine the value of industrial waste heat for district heating systems

Using industrial waste heat increases primary energy efficiency and may reduce costs. District heating networks are a promising sink as temperatures are relatively low. Usually only the end-use prices are public; but these include network infrastructure costs, maintenance costs etc. The value of a certain kWh fed in, i.e. the current marginal costs for the generation of heat, are not transparent. However, current marginal generation costs are decisive for the use of waste heat as the accumulated producer surplus determines the profitability of investment. To make marginal generation costs transparent, a “Heat Merit Order” is constructed. Based on conversion factors, fuel prices, network tariffs, etc. the maximum remuneration payed by the district heating operator at a certain point of time is made calculable. For a case study, the applicability to estimate maximum investment costs is proven. In conclusion, the Heat Merit Order makes local heat generation prices transparent and allows to calculate the profitability of integrating waste heat, other heat sources and storages; it enables companies to estimate the value of waste heat and if investments are profitable. Finally, the Heat Merit Order avoids information asymmetries and thus generally supports the efficiency and penetration of district heating.

Non-linear Non-Iterative transient inverse conjugate heat transfer method applied to microelectronics

Solving for temperature profiles given boundary conditions, geometry, and material properties is relatively straightforward given the wealth of analytical and computational techniques available. However, experimentally we often measure temperatures and seek to understand unknown boundary conditions or material properties. This problem is generally ill-posed. Thus, to get the value of these input parameters, we use inverse methods: knowing the output of the system (i.e., temperature), we can compute the value of the unknown parameters (e.g., thermal conductivity or heat fluxes). In microelectronics, the location and magnitude of the boundary conditions including local heat generation rates are often unknown or difficult to model due to the compactness of the current microchips and active thermal management schemes that distribute computations between different cores causing time-varying heat generation within the chips. This information can be retrieved using inverse heat transfer methodologies by tracking the temperature distributions in space and time. In this work, we develop a new, non-iterative inverse methodology to retrieve the heat flux inside of 3D geometries of stacked microchips. This method not only provides good agreement between the imposed and the retrieved heat flux with a linear form of the heat diffusion equation, but also predicts the imposed heat flux with good accuracy in situations with non-linearities. Here we numerically and experimentally validate our new approach using a microchip with 25 heaters that can be operated independently to create different spatial and temporal heat flux patterns. During testing, the system is in a controlled environmental chamber and the temporal and spatially varying temperature of the top surface of the chip is measured using infrared thermography for input to the inverse method. The system and model include non-linearities through varying convective heat transfer boundary conditions on different parts of a test article and temperature-dependent thermal properties of the constituent materials. The inverse methodology retrieves the local heat generation rates with good agreement in time, space, and magnitude. An uncertainty analysis of the computation and the experiments is also detailed. Our methodology is unique compared to past work because non-linearity is solved without the need of using iterative processes, which makes the algorithm computationally efficient. Ultimately, this method is useful for the determination of the location and magnitude of the heat flux in any 3D system based on external temperature measurements with real heat transfer properties without the need of an iterative procedure.

Time-resolved temperature-jump measurements and steady-state thermal imaging of nanoscale heat transfer of gold nanostructures on AlGaN:Er3+ thin films.

For a nanostructure sitting on top of an AlGaN:Er3+ thin film, a new thermal imaging technique is presented where dual cameras collect bandpass filtered videos from the H and S bands of Er3+ emission. We combine this thermal imaging technique with our newly developed time-resolved temperature measurement technique which relies on luminescence thermometry using Er3+ emission. This technique collects time-resolved traces from the H and S bands of Er3+ emission. The H and S signal traces are then used to reconstruct the time-resolved temperature transient when a nanostructure is illuminated with a pulsed 532 nm light. Two different types of samples are interrogated with these techniques (drop-casted gold nanosphere cluster and lithographically prepared gold nanodot) on the AlGaN:Er3+ film. Steady-state and time-resolved temperature data are collected when the samples are immersed in air and water. The results of time-resolved temperature-jump measurements from a cluster of gold nanospheres show extremely slow heat transfer when the cluster is immersed in water and nearly 200-fold increase when immersed in air. The low thermal diffusivity for the cluster in water suggests poor thermal contact between the cluster and the thermal bath. The lithographically prepared nanodot has much better adhesion to the AlGaN film, resulting in much higher thermal diffusivity in both air and water. This proof-of-concept demonstration opens a new way to measure the dynamics of the local heat generation and dissipation at the nanoparticle-media interface.

The Influence of Structure on the Electrochemical and Thermal Response of Li-Ion Battery Electrodes

Abstract Advancement of lithium-ion batteries for transportation applications requires addressing two key challenges: increasing energy density and providing fast charging capabilities. The first of these challenges can be met using thicker electrodes. However, the implementation of thick electrodes inherently presents a trade-off with respect to fast charging. As the thickness is increased, transport limitations reduce the ability of the battery to meet aggressive charge conditions. At the particle scale, interactions between solid diffusion and reaction kinetics influence the effective storage of lithium. At the electrode scale, diffusion limitations can lead to local variations in salt concentrations and electric potential. These short-range and long-range effects can combine to influence local current and heat generation. In the present work, a pseudo-2D lithium-ion battery model is applied to understand how active material particle size, porosity, and electrode thickness impact local field variables, current, heat generation, and cell capacity within a single-cell stack. The model was built assuming that the active particles are representative spherical particles. The governing equations and boundary conditions were set following the common Newman model. Cell response under varied combinations of charge and discharge cycling is assessed for rates of 1 C and 5 C. Aggressive charge and discharge conditions lead to locally elevated C-rates and attendant increases in local heat generation. These variations can be impacted in part by tailoring electrode structures. To this end, results for parametric studies of active material particle size, porosity, and electrode thickness are presented and discussed.

Fingerprinting Redox Heterogeneity in Electrodes during Extreme Fast Charging

Conventionally, battery electrodes are rationalized as homogeneous reactors. It proves to be an erroneous interpretation for fast transients, where mass transport limitations amplify underlying heterogeneities. Given the lack of observability of associated fast spatiotemporal dynamics, redox activity in inhomogeneous electrodes is superficially explored. We resort to a physics-based description to examine the extreme fast charging of lithium-ion battery electrodes. Representative inhomogeneity information is extracted from electrode tomograms. We discover such electrodes to undergo preferential intercalation, localized lithium plating and nonuniform heat generation as a result of distributed long- and short-range interactions. The spatial correlations of these events with the underlying inhomogeneity are found to be nonidentical. Investigation of multiple inhomogeneity fields reveals an exponential scaling of plating severity and early onset in contrast to the homogeneous limit. Anode and cathode inhomogeneities couple nonlinearly to grow peculiar electrodeposition patterns. These mechanistic insights annotate the complex functioning of spatially nonuniform electrodes.

Thermal deformation of gold nanostructures and its influence on surface plasmon resonance sensing.

Plasmonic nanostructures have been recently used in elevated temperature applications such as sensing of high-energy systems and localized heat generation for heat-assisted magnetic recording, thermophotovaltaics, and photothermal therapy. However, plasmonic nanostructures exposed to elevated temperature often experience permanent deformations, which could significantly degrade performance of the plasmonic devices. Therefore, understanding of thermal deformation of plasmonic nanostructures and its influence on the device performance is essential to the development of robust high-performance plasmonic devices. Here, we report thermal deformation of lithographic planar gold nanopatch and nanohole arrays and its influence on surface plasmon resonance sensing. The gold nanostructures are fabricated on a silicon substrate and on the end-face of an optical fiber using electron-beam lithography and focused-ion-beam lithography, respectively. The fabricated gold nanostructures are exposed to cyclic thermal loading in the range of 25 °C to 500 °C. Through experimental and numerical studies, we investigate (i) thermal deformation modes of the gold nanostructures, (ii) influence of the gold nanostructure geometry on the degree and mechanism of the thermal deformation, and (iii) influence of the thermal deformation on performance of surface plasmon resonance sensing. The obtained understanding from these studies is expected to help guide the development of robust high-performance plasmonic sensors for monitoring in elevated temperature environments. Although the current work is focused on gold nanostructures, it can be extended to provide useful insights on thermal deformation of refractory plasmonic nanostructures at extreme temperature.

Effect of micro-EDM machining parameters on the accuracy of micro hole drilling in Zr-based metallic glass

Micro drilling of metallic glass is a technologically important research due to recent development of metallic glass and their technological niche applications in field of micro nozzles, micro-electro mechanical systems (MEMS) and bio-implants. Micro drilling of metallic glass is a challenging work because of in situ crystallization of resultant workpiece due to localized high heat generation during machining. However, micro-electrical discharge machining (Micro-EDM) eludes the limitations of conventional machining methods and offers precise machining of metallic glass with good surface properties. Micro-EDM machining parameters exerts a big influence on the machined features and their surface properties. A study of effect of micro-EDM machining parameters on machined geometry’s features and optimization of machining parameters for accurate machining of metallic glasses are very essential owing to the recent advancements in the applicability of Micro-EDM for processing of metallic glass parts. In present work micro-EDM is used for precision drilling of micro holes in metallic glasses. The levels of input micro-EDM machining parameters such as capacitance, voltage, tool revolutions per minutes (RPM) for optimum accuracy of micro holes and minimum machining time are identified. Resultant of present work culminated to the establishment of micro holes with exceptional accuracy using micro-EDM. The tool RPM is found to be a key parameter for increasing hole accuracy as well as reducing machining time. Outcome of present work may pave application of metallic glasses products based on precision engineering.

Fabrication of BaSnO3 thin films on SiO2 glass substrates using excimer laser-assisted metal organic decomposition

The perovskite oxide BaSnO3 has received much attention because of its excellent electronic properties for use in electronic devices such as solar cells. In this study, BaSnO3 thin films were successfully deposited onto SiO2 glass substrates using excimer laser-assisted metal organic decomposition (ELAMOD). The films could not be obtained using the thermal decomposition process because Ba reacts readily with a SiO2 substrate. Results of a transmission electron microscopy and numerical simulation of heat generation and transfer under laser irradiation revealed local and rapid generation of heat in the ELAMOD process resulting in a suppression of the reaction between Ba and SiO2 and hence enabling BaSnO3 thin film formation on SiO2 substrates.

In-situ diagnostic tools for hydrogen transfer leak characterization in PEM fuel cell stacks part III: Manufacturing applications

This work describes a novel diagnostic technique for detection and isolation of manufacturing defects in polymer electrolyte fuel cell stacks. Two of the main causes of early stack failure are membrane pinholes and electric shorts. Membrane pinholes result in the local hydrogen crossover from anode to cathode, which reduces fuel utilization. With the growth of the pinhole, the crossed over hydrogen exits the cathode as hydrogen emission. When this emission passes the safe lower explosion limit of 4% hydrogen in air, the stack reaches its end of life (EOL). Alternatively, a low resistive point between the anode and cathode results in current flow through the contact point and local heat generation. This could burn the membrane and result in EOL of the fuel cell stack. A diagnostic technique is proposed to detect cells in which membrane pinholes or electric short occur. The technique allows both failure mechanisms to be isolated by means of a straightforward algorithm. The detection of the failure can be used as a pass/fail criterion during fuel cell stack manufacturing, whereas the isolation of the failure modes can be used to inform suitable repair procedures to be performed on the failed stacks.

A thermodynamically consistent framework for non‐isothermal modelling of local heat generation and electromotive force in SOFC single electrodes

AbstractMathematical models for single electrode reversible heat and non‐isothermal electromotive force (EMF) of a solid oxide fuel cell (SOFC) are developed. These models estimate the volumetric reversible heat generation and EMF of electrochemical reactions, within each electrode at local conditions of temperature and pressure, based on entropy change of half reactions. The resulting equations are thermodynamically consistent. They inherently obey the conservation of energy law as the electrochemical energy released added to the heat of reactions at each electrode equate the enthalpy change of the reacted species. The equations are implemented to model electrodes in a tubular micro‐ solid oxide fuel cell (TμSOFC). The thermodynamic consistency of the model is numerically confirmed as the enthalpy of the reactants equates the electric energy released by the cell plus the sum of electrode heats plus electrolyte Ohmic heat. The effect of thermal gradients on the cell's overall EMF is found to be negligible. The reversible and irreversible heat generation of each electrode are distinguished. Overall, the anode is found to be endothermic, and the cathode exothermic.

Impact of electromagnetic fields and heat on spin transport signals in Y3Fe5O12

Exploring new strategies to perform magnon logic is a key requirement for the further development of magnon-based spintronics. In this work, we realize a three-terminal magnon transport device to study the possibility of manipulating magnonic spin information transfer in a magnetic insulator via localized magnetic fields and heat generation. The device comprises two parallel Pt wires as well as a Cu center wire that are deposited on the ferrimagnetic insulator Y$_{3}$Fe$_{5}$O$_{12}$. While the Pt wires act as spin current injector and detector, the Cu wire is used to create local magnetostatic fields and additional heat, which impact both the magnetic configuration and the magnons within the Y$_{3}$Fe$_{5}$O$_{12}$ below. We show that these factors can create a non-local signal that shows similar features as compared to an electrically induced magnon flow. Furthermore, a modulation of the spin transport signal between the Pt wires is observed, which can be partly explained by thermally excited spin currents of different polarization. Our results indicate a potential way towards the manipulation of non-local magnon signals, which could be useful for magnon logic.

Experimental investigations into mechanical and thermal properties of rapid manufactured copper parts

In the present paper, mechanical and thermal properties of rapidly manufactured copper parts were studied. The combination of three-dimensional printing and ultrasonic assisted pressureless sintering was used to fabricate copper parts. First, the ultimate tensile strength and thermal conductivity were compared between ultrasonic assisted and conventional pressureless sintered samples. The homogenously mixing of particles and local heat generation by ultrasonic vibrations promoted the sintering driving process and resulted in better mechanical and thermal properties. Furthermore, response surface methodology was adopted for the comprehensive study of the ultrasonic sintering parameters (sintering temperature, heating rate, and soaking time with ultrasonic vibrations) on ultimate tensile strength and thermal conductivity of the fabricated sample. Analysis of variance was performed to identify the significant factors and interactions. The image processing method was used to identify the surface porosity at different parameter levels to analyse the experimental results. High ultimate tensile strength was obtained at high sintering temperature, long soaking time, and slow heating rate with low surface porosity. After 60 min of soaking time, no significant effect was observed on the thermal conductivity of the fabricated sample. The significant interactions revealed less effect of soaking time at low sintering temperatures for ultimate tensile strength and less effect of heating rate at low sintering temperatures for thermal conductivity. Multi-objective optimization was carried out to identify parameters for maximum ultimate tensile strength and maximum thermal conductivity.

Prediction of Local Water Distributions and Performance of PEMFC using Pore Network Modeling

Oxygen transport and water drainage in the cathode side Catalyst Layer (CL) affect the performance of Polymer Electrolyte Fuel Cells (PEFC). A unique mathematical model has been developed to track local fluxes of water, both liquid in pores and lambda in the ionomer, through a fuel cell electrode. The local pressure, temperature, and heat generation is also predicted. The role of pore size distribution, ionomer to carbon (I/C) ratios, RH, and operating conditions on fuel cell performance has been studied. The results and polarization curves provide insight as to how local water balances affect electrode performance.

Mesoscale Implications of Electrode-Scale Heterogeneity on Performance and Degradation

Lithium-ion battery electrodes are pivotal to attaining high energy and power dense batteries towards vehicle electrification. These electrodes attribute spatial heterogeneity at different scales (particle, pore, electrode) stemming from the electrode processing steps. Particularly, the inhomogeneity in the negative electrode can be ascribed to the spatial variation of active material (graphite) and the polymeric binder. The inherent inhomogeneity at different scales can translate to non-uniform kinetic and transport resistance. These effects can foster higher over-potentials, restraint ionic transport with localized potential drop and heat generation. The localized heterogeneity coupled with anode centric degradation behavior can also facilitate preferential lithium plating. This study elucidates the mesoscale implications of the electrode-scale heterogeneity on the coupled thermo-electrochemical response in terms of performance and degradation.

Pulsed Laser Activation of Carbene Bioadhesive Boosts Bonding Strength

AbstractLight‐activated tissue adhesives are limited to low light doses (50 J) and intensities (<1 W cm−2) due to photo‐to‐thermal heat generation. Low intensities have the disadvantage of limited penetration depths with retarded crosslinking kinetics, which impairs carbene‐based crosslinking strategies that compete with nitrogen evolution and gas nucleation. These limitations are circumvented by a trade‐off between high‐intensity activation while reducing the exposure surface area. Continuous or pulsed activation by line scanning the carbene precursor adhesive allows curing a higher surface area/volume ratio while preventing localized heat generation. By optimizing irradiation with a pulsed laser scan, the adhesion strength is improved by 17‐fold over ultraviolet A (UVA) light emitting diodes (LEDs) and is on par with bioadhesive gold standard of topical cyanoacrylates. Overall, this improved method of photo‐activation applies to other industrial and clinical photocuring adhesives where limits on UVA dose constrain exposure intensities.

Polymeric Reactor for the Synthesis of Superparamagnetic-Thermal Treatment of Breast Cancer.

Engineered superparamagnetic iron oxide nanoparticles (SPIONs) have been studied extensively for their localized homogeneous heat generation in breast cancer therapy. However, challenges such as aggregation and inability to produce sub-10 nm SPIONs limit their potential in magnetothermal ablation. We report a facile, efficient, and robust in situ method for the synthesis of SPIONs within a poly(ethylene glycol) (PEG) reactor adsorbed onto reduced graphene oxide nanosheets (rGO) via the microwave hydrothermal route. This promising modality yields crystalline, stable, biocompatible, and superparamagnetic PEGylated SPION-rGO nanocomposites (NCs) with uniform dispersibility. Our findings show that rGO acts as a breeding ground for the spatially distributed nanosites around which the ferrihydrite seeds accumulate to ultimately transform into immobilized SPIONs. PEG, in parallel, acts as a critical confining agent physically trapping the accumulated seeds to prevent their aggregation and create multiple domains on rGO for the synthesis of quantum-sized SPIONs (9 ± 1 nm in diameter). This dual functionality (rGO and PEG) exhibits a pronounced effect on reducing both the aggregation and the sizes of fabricated SPIONs as confirmed by the scanning transmission electron microscopy images, dynamic light scattering analyses, and the specific absorption rates (SARs). Reduced aggregation lowered the toxicity of NCs, where PEGylated SPION-rGO NCs are more biocompatible than PEGylated SPIONs, showing no significant induction of cell apoptosis, mitochondrial membrane injury, or oxidative stress. Significantly less lactate dehydrogenase release and hence less necrosis are observed after 48 h exposure to high doses of PEGylated SPION-rGO NCs compared with PEGylated SPIONs. NCs induce local heat generation with a SAR value of 1760 ± 97 W/g, reaching up to 43 ± 0.3 °C and causing significant MCF-7 breast tumor cell ablation of about 78 ± 10% upon applying an external magnetic field. Collectively, rGO and PEG functionalities have a synergistic effect on improving the synthesis, stability, biocompatibility, and magnetothermal properties of SPIONs.

Scaling Analysis of a Li-Ion Pouch Cell Via a Simplified Electrochemical/Thermal Model

Owing to their merits of high energy density, low self-discharge and absence of memory effects, Li-ion batteries have become the leading energy storage devices for consumer electronics and electric vehicles. Thermal management of large-format Li-ion cells is crucial because of their small surface-to-volume ratios. High temperature and temperature inhomogeneity can lead to locally irregular degradation of active electrode materials, or even catastrophic thermal runaway [1]. Spatially variable internal temperatures are commonly observed in large-format batteries, and have been shown to impact performance and cycle life significantly [2-4]. Since cell temperature can strongly affect the physical properties and reaction kinetics within a battery, it is vital to understand the heat generation and transient temperature within a cell during charging/discharging. An experimentally validated electrochemical/thermal cell model is therefore necessary to predict and optimize operational parameters. Currently, thermal simulations are primarily based on equivalent circuit models (ECM) and electrochemical models [5]. Due to their simplicity, ECMs can be solved quickly, favoring their use in battery management systems (BMSs). In contrast, electrochemical models describe the basic electrochemical and physical processes through detailed local descriptions accounting for the conservation of charge, mass and energy, etc. The most popular electrochemical Li-ion battery model was developed by Fuller, Doyle, and Newman [6, 7]. In this study, we demonstrate a simplified 3D electrochemical model for large format Li-ion prismatic pouch cell, which achieves computational efficiency by reducing the P2D model to the simpler structure originally developed by Newman and Tobias [8]. The model has advantages of both ECM and continuum models, that is, it is fast enough for performance prediction and thermal management while still retaining physical information that can be ascribed to microscopic charge and mass transport phenomena. A scaling analysis is carried out via non-dimensionalization of the cell model. Several key dimensionless numbers are shown to govern the dynamic performance of the battery during charging and discharging. The complexity of the model, such as the number of cell layers and mesh scheme, can be reduced by asymptotic analysis to make the model more time-efficient. The non-uniformity of both state of charge (SOC) and temperature within the cell are attributed to non-uniformity of the 3D current-density distribution, and also to the anisotropic nature of the thermal conductivity tensor. The relative importance of the fundamental dimensionless quantities in controlling local heat generation and thermal evolution will be discussed.