Laurent Pilon

Laurent Pilon
University of California, Los Angeles | UCLA · Department of Mechanical and Aerospace Engineering

PhD

About

249
Publications
38,778
Reads
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8,139
Citations
Introduction
Laurent Pilon is Full Professor in Mechanical and Aerospace Engineering at UCLA. His research group is engaged in a wide range of interdisciplinary research projects at the intersection between interfacial and transport phenomena, material science, and biology for sustainable energy technologies. He is the recipient of the NSF CAREER Award, the Bergles-Rohsenow Young Investigator Award in Heat Transfer from ASME, and the JQSRT Young Scientist Award in Radiative Transfer from Elsevier.
Additional affiliations
July 2012 - present
University of California, Los Angeles
Position
  • Professor
July 2008 - June 2012
University of California, Los Angeles
Position
  • Professor (Associate)
July 2002 - July 2008
University of California, Los Angeles
Position
  • Professor (Assistant)
Education
January 1999 - August 2002
Purdue University
Field of study
  • Mechanical Engineering
September 1994 - September 1997

Publications

Publications (249)
Article
Water droplets are commonly observed on the inner or outer surface of solar energy conversion systems due to rain or condensation. These droplets affect the systems’ efficiency and thermal load. This study experimentally and numerically investigates infrared radiation transfer through semitransparent windows covered with droplets on their front or...
Article
This study compares the charging mechanisms, thermodynamics, lithium ion transport, and operando isothermal calorimetry in lithium-ion battery electrodes made of Ti2Nb2O9 microparticles or nanoparticles synthesized by solid-state or sol-gel methods, respectively. First, electrochemical testing showed that electrodes made of Ti2Nb2O9 nanoparticles e...
Article
Shear-phase early transition metal oxides, mostly of Nb, and comprising edge- and corner-shared metal–oxygen octahedra have seen a resurgence in recent years as fast-charging low-voltage electrodes for Li–ion batteries. Mo oxides, broadly, have been less well studied. Here we examine the reduced Mo oxide Mo4O11 that has a structure comprising only...
Article
Ti 2 Nb 2 O 9 has been identified as a promising lithium-ion battery anode material with large specific capacity, small cycling degradation, and good capacity retention at large currents. This study aims to gain insight into the charging mechanisms as well as the thermodynamics and ion transport in Ti 2 Nb 2 O 9 synthesized by the solid state or th...
Article
Lithium-ion batteries (LIBs) featuring high energy density have received particular attention in recent years due to their promise as electrical energy storage devices for electric vehicles and portable electronic devices. However, most of the commercial LIBs use graphite anode which suffer from the formation of solid-electrolyte interface (SEI) la...
Article
Outdoor raceway ponds for microalgae cultivation suffer from low biomass productivity due in part to the low photosynthetic photon flux received by the microalgae culture in the mornings and evenings and during the winter months at middle and high latitudes. This study explores the use of external mirrors to reflect additional sunlight onto the cul...
Article
The production of Ca(OH)2 via thermal decomposition of limestone is an energy intensive process resulting in significant CO2 emissions. However, if produced in a manner that obviates the need for the thermal decomposition of limestone, Ca(OH)2 could be a “CO2-negative” material. Herein, we design and demonstrate the operation of a continuous, low-t...
Article
Hysteresis is a phenomenon that pervades both the physical and social sciences. While commonly associated with magnetism, it also occurs in a wide variety of other materials, including ferroelectrics and shape memory alloys. Hysteresis emerges when a particular property has a history dependence. It is exploited in microelectronic memory, logic, and...
Article
The Wadsley–Roth compound PNb9O25 is a promising fast charging lithium ion battery anode material with high operating voltage to prevent solid electrolyte interface formation. Here, we present potentiometric entropy measurements featuring signatures of semiconductor-to-metal transition and intralayer ordering upon lithiation in the anode material P...
Article
Full-text available
This paper aims to systematically investigate the effect of gas bubbles formation on the performance of a horizontal photoelectrode exposed to normally incident light during photoelectrochemical water splitting. The presence...
Article
This study demonstrates, for the first time, the use of reversible sequin fabrics as inexpensive, scalable, and durable variable emittance surfaces. First, the spectral normal-hemispherical reflectance's of commercially available gold/black and silver/black reversible sequin fabrics were measured at room temperature for wavelength between 0.25 and...
Article
This study presents a theoretical framework to model spatio-temporal heat generation rates and temperature evolution in electrochemical double layer capacitors composed of porous electrodes during constant-current cycling. Expressions for reversible and irreversible heat generation rates are derived based on porous electrode theory. Temperature pre...
Article
This paper reports and analyzes, for the first time, the effective Young's modulus and hardness of nanoparticle-based silica aerogels and xerogels with porosity ranging from 46 to 81%. Pure silica aerogel and xerogel monoliths were synthesized by (i) gelation of aqueous suspensions of silica nanoparticles on omniphobic substrates (PTFE or perfluoro...
Article
This study evaluates the effect of dependent scattering and particle overlapping on the integral radiation characteristics of fractal aggregates of monodisperse and non-absorbing spherical particles for a wide range of particle and aggregate sizes. It also aims to identify a scattering approximation capable of rapidly predicting these radiation cha...
Article
This paper presents a novel sol-gel method to synthesize large and thick silica aerogel monoliths at near ambient conditions using a commercial aqueous solution of colloidal silica nanoparticles as building blocks. To achieve slabs with high visible transmittance and low thermal conductivity, the method combines the strategies of (i) synthesizing g...
Article
This study establishes that the deviation of large pendant droplets from an ideal cap-shape due to gravity can have significant and complex impacts on the normal-hemispherical and directional-hemispherical transmittances of light through horizontal and tilted transparent windows. First, the shape of pendant droplets larger than the capillary length...
Article
This study investigates experimentally the impact of droplets on the performance of solar photovoltaic (PV) cells due to dropwise condensation or rain falling on their cover. Dew formation occurs frequently in various climates including in semi-arid regions suitable to PV cell deployment. Then, droplets present on the cover of solar cells can negat...
Article
The shear-phase compound TiNb2O7 has recently emerged as a safe and high-volumetric density replacement for graphite anodes in lithium ion batteries. An appealing feature of TiNb2O7 is that it retains capacity even at high cycling rates. Here, we demonstrate that phase pure and crystalline TiNb2O7 can be rapidly prepared using a high-temperature mi...
Article
This study investigates the effect of temperature on the heat generation and the associated electrochemical phenomena occurring in IL-based EDLCs. The EDLCs consisted of two identical activated carbon electrodes with neat Pyr14TFSI or Pyr14TFSI diluted in propylene carbonate (PC) as electrolytes. The instantaneous heat generation rate at each elect...
Article
Designing thermal diodes is attracting a considerable amount of interest recently due to the wide range of applications and potentially high impact in the transportation and energy industries. Advances in nanoscale synthesis and characterization are opening new avenues for design using atomic-level tools to take advantage of materials properties in...
Article
Full-text available
This study investigates the effect of condensed water droplets on the areal biomass productivity of outdoor culture systems with a free surface, protected by a transparent window or cover to prevent contamination and to control the growth conditions. Under solar radiation, evaporation from the culture causes droplets to condense on the interior sur...
Article
Full-text available
Calcium hydroxide (Ca(OH)2), a commodity chemical, finds use in diverse industries ranging from food, to environmental remediation and construction. However, the current thermal process of Ca(OH)2 production via limestone calcination is energy- and CO2-intensive. Herein, we demonstrate a novel aqueous-phase calcination-free process to precipitate C...
Article
This paper quantifies experimentally the effect of pendant droplets condensed on the back of semi-transparent glass panes on their normal-hemispherical transmittance and reflectance in the visible and near-infrared. To enable sample characterization and ensure repeatability, acrylic droplets were deposited on the back side of 3 mm-thick soda-lime s...
Article
We report a significant advance in thermally insulating transparent materials: silica-based monoliths with controlled porosity which exhibit the transparency of windows in combination with a thermal conductivity comparable to aerogels.The lack of transparent, thermally insulating windows leads to substantial heat loss in commercial and residential...
Preprint
div>The shear-phase compound TiNb<sub>2</sub>O<sub>7</sub> has recently emerged as a safe and high-volumetric density replacement for graphite anodes in lithium ion batteries. An appealing feature of TiNb<sub>2</sub>O<sub>7</sub> is that it retains capacity even at high cycling rates. Here we demonstrate that phase pure and crystalline TiNb<sub>2</...
Preprint
This study investigates the effect of temperature on the heat generation and the associated electrochemical phenomena occurring in IL-based EDLCs. The EDLCs consisted of two identical activated carbon electrodes with neat Pyr<sub>14</sub>TFSI or Pyr<sub>14</sub>TFSI diluted in propylene carbonate (PC) as electrolytes. The instantaneous heat gener...
Article
This study elucidates the effect of colony formation on light absorption by Botryococcus braunii microalgae cells. The spectral average mass absorption cross-section of suspensions of B. braunii cultures with free-floating cells or colonies was measured experimentally across the photosynthetically active radiation region. The average mass absorptio...
Article
This study investigates systematically the effects of nonabsorbing droplets on the bidirectional transmittance of transparent windows. The Monte Carlo ray-tracing method was used to predict the bidirectional transmittance of transparent windows supporting monodisperse or polydisperse and randomly distributed droplets on their front side or backside...
Article
This work investigates the effect of wall thickness on the thermal conductivity of mesoporous silica materials made from different precursors. Sol-gel and nanoparticle-based mesoporous silica films were synthesized by evaporation-induced self-assembly using either tetraethyl orthosilicate or pre-made silica nanoparticles. Since wall thickness and p...
Article
This study reports for the first time, isothermal calorimetric measurements of the instantaneous heat generation rate at each electrode of ionic liquid-based electric double layer capacitors (EDLCs) at different temperatures. Indeed, EDLCs generate reversible and irreversible heat during normal operation and the properties of ionic liquids are know...
Article
Independent scattering refers to situations when particles are sufficiently distant that some of the radiation characteristics of particle systems can be determined by adding the contributions of each particle. When particles are in close proximity, however, dependent scattering prevails and is affected by near-field interactions and far-field inte...
Article
An in operando calorimeter was used to investigate the effect of potential window on heat generation in EDLCs consisting two identical activated carbon electrodes with either neat Pyr14TFSI or 1 M Pyr14TFSI in PC electrolytes. First, the heat generation rates at the positive and negative electrodes differed significantly in neat IL due to the diffe...
Article
Full-text available
Many living organisms track light sources and halt their movement when alignment is achieved. This phenomenon, known as phototropism, occurs, for example, when plants self-orient to face the sun throughout the day. Although many artificial smart materials exhibit non-directional, nastic behaviour in response to an external stimulus, no synthetic ma...
Article
This study theoretically and rigorously validates the use of the recently proposed step potential electrochemical spectroscopy (SPECS) and multiple potential step chronoamperometry (MUSCA) methods and their fitting analysis for determining the respective contributions of electrical double layer (EDL) and faradaic reactions to charge storage in pseu...
Article
This study compares systematically contact profilometry, interferometry, ellipsometry, ellipsometric porosimetry, and nitrogen porosimetry for measuring thickness, effective refractive index, and/or porosity of mesoporous thin films. Indeed, such measurements are crucial in elucidating the structure-property relationships of mesoporous materials. H...
Article
Full-text available
This paper presents a novel template-free water-based sol–gel method to synthesize thick transparent and thermally insulating mesoporous silica monolithic slabs by gelation and drying of a colloidal suspension of silica nanoparticles under ambient conditions. For the first time, mesoporous silica slabs were synthesized on perfluorocarbon liquid sub...
Article
This study aims to investigate the thermal signature associated with the charge storage mechanisms in hybrid supercapacitors using in operando calorimetry under constant current cycling. The hybrid supercapacitors consisted of highly porous pseudocapacitive electrode and activated carbon (AC) electrode with either organic or aqueous electrolytes. P...
Article
Here, we report fabrication of flexible all solid-state transparent electrochromic patterned micro-supercapacitors based on two-dimensional layered nanostructured molybdenum oxide (MoO3-x)/poly(3,4-ethylene dioxythiophene) polystyrene sulfonate (PEDOT:PSS) nanocomposite electrodes. Exceptional electrochemical performance of the transparent micro-su...
Article
This study examines experimentally and numerically the effects of microencapsulated phase change material (PCM)additions on temperature rise and cool-down rate, and the associated impact on reducing the risk of thermal cracking in concrete pavements. Specimens representative of a realistic pavement geometry were exposed to diurnal temperature cycli...
Article
This study aims to computationally generate and fully characterize realistic three-dimensional mesoporous materials. Notably, a new algorithm reproducing gas adsorption porosimetry was developed to calculate the specific surface area and pore size distribution of computer-generated structures. The diffusion-limited cluster-cluster aggregation (DLCC...
Article
This study aims to investigate time-dependent heat generation in all-solid-state supercapacitors. Supercapacitors were fabricated by assembling two identical electrodes made of graphene petal arrays grown on buckypaper by microwave plasma chemical vapor deposition. The electrodes were separated by either (i) a conventional phosphoric acid in polyvi...
Article
Based on systematic experimental interrogation of the aqueous dissolution behavior of a large selection of minerals – whose dissolution rates vary by several orders of magnitude – this study demonstrates that acoustic perturbation yields an unprecedented enhancement in dissolution kinetics, which scales with the mineral’s hardness and average bond...
Article
This paper is concerned with direct energy conversion of waste heat into electrical energy by performing the Olsen cycle on lead nickel niobate zirconate titanate (PNNZT) pyroelectric ceramics undergoing a relaxor-ferroelectric phase transition. First, isothermal bipolar displacement vs. electric field hysteresis loops were measured for different t...
Article
This study aims to provide physical interpretation of electrochemical impedance spectroscopy (EIS) measurements for redox active electrodes in three electrode configuration. To do so, a physicochemical transport model was used accounting for (i) reversible redox reactions at the electrode/electrolyte interface, (ii) charge transport in the electrod...
Article
The use of statistical and machine learning approaches to predict the compressive strength of concrete based on mixture proportions, on account of its industrial importance, has received significant attention. However, previous studies have been limited to small, laboratory-produced data sets. This study presents the first analysis of a large data...
Article
This paper quantifies the effect of surface hydroxyl groups on the effective specific and volumetric heat capacities of mesoporous silica. To achieve a wide range of structural diversity, mesoporous silica samples were synthesized by various methods, including (i) polymer-templated nanoparticle-based powders, (ii) polymer-templated sol-gel powders,...
Article
This study presents a convenient approach to rapidly assess the thermal performance of building envelopes containing phase change materials (PCMs) or other building materials. It establishes that the transient thermal behavior of full-scale building test structures featuring envelopes with PCMs can be represented by a reduced-scale test cell conven...
Article
Heat generation in electric double layer capacitors (EDLCs) may lead to temperature rise and reduce their lifetime and performance. This study aims to measure the time-dependent heat generation rate in individual carbon electrode of EDLCs under various charging conditions. First, the design, fabrication, and validation of an isothermal calorimeter...
Article
The production of ordinary portland cement (OPC) is a CO2 intensive process. Specifically, OPC clinkering reactions not only require substantial energy in the form of heat, but they also result in the release of CO2; i.e., from both the decarbonation of limestone and the combustion of fuel to provide heat. To create alternatives to this CO2 intensi...
Article
Full-text available
This study aims to investigate the effect of electrode composition on heat generation in electric double layer capacitor (EDLC) electrodes under galvanostatic cycling. EDLCs consist of two identical electrodes usually made of a mixture of (i) carbon-based material, (ii) binder, and (iii) other conductive additives. These constituents were found to...
Article
Electrochemical impedance spectroscopy (EIS) consists of plotting Nyquist plots representing the imaginary versus the real parts of the complex impedance of individual electrodes or electrochemical cells. To date, interpretations of Nyquist plots have been based on physical intuition and/or on the use of equivalent RC circuits. However, physical in...
Article
This study aims to investigate the effect of electrode nanoarchitecture on the performance of electric double layer capacitor (EDLC) porous electrodes consisting of highly-ordered monodisperse spherical carbon nanoparticles. To do so, cyclic voltammograms, reproducing three-electrode measurements, were numerically generated for electrodes with diff...
Article
This study examined the benefits of adding microencapsulated phase change materials (PCMs) to concrete pavement sections so as to limit temperature rise and the development of temperature gradients due to exothermic cement hydration reactions and environmental exposure at early-ages. Isothermal calorimetry measurements of the heat generation rate a...
Article
This study aims to investigate systematically light transfer through semitransparent windows with absorbing cap-shaped droplets condensed on their backside as encountered in greenhouses, solar desalination plants, photobioreactors and covered ponds. The Monte Carlo ray-tracing method was used to predict the normal-hemispherical transmittance, refle...
Article
Composite structures for electrochemical energy storage are prepared based on using the high rate lithium-ion insertion properties of Nb2O5. The Nb2O5 anchored on reduced graphene oxide (rGO) by hydrothermal synthesis to improve charge transfer properties and, by controlling surface charge, the resulting Nb2O5-rGO particles are attached to a high s...
Article
This study investigates the durability of cementitious composites containing microencapsulated phase change materials (PCMs). First, the stability of the PCM's enthalpy of phase change was examined. A reduction of around 25% in the phase change enthalpy was observed, irrespective of PCM dosage and aging. Significantly, this reduction in enthalpy wa...
Article
This study examined the effects of spherical core-shell particle inclusions, such as microencapsulated phase change materials (PCMs), on the thermal deformation behavior of cement-based composites. First, simulations of volumetric thermal deformation in representative microstructures were carried out, based on the finite element method (FEM), to pr...
Article
This paper experimentally and theoretically investigates light transfer in agar-immobilized cell cultures. Certain biotechnological applications such as production of metabolites secreted by photosynthetic microorganisms require cells to be immobilized in biopolymers to minimize contamination and to facilitate metabolite recovery. In such applicati...
Article
This study aims to quantify systematically the effect of non-absorbing cap-shaped droplets condensed on the backside of transparent windows on their directional-hemispherical transmittance and reflectance. Condensed water droplets have been blamed to reduce light transfer through windows in greenhouses, solar desalination plants, and photobioreacto...
Article
This paper extends the admittance method to predict the diurnal energy flux reduction Er associated with adding microencapsulated phase change materials (PCM) to single and multilayer building envelopes. The effects of phase change on the thermal load through composite building walls were accounted for by modifying the decrement factor fAM and time...
Article
This paper investigates the effects of adding microencapsulated phase change materials (PCM) on the thermal conductivity of cement paste and cement mortar composites. Embedding cementitious composites with microencapsulated PCM has been considered a promising method for increasing the thermal mass of buildings to achieve greater energy efficiency a...
Article
This study aims to investigate the effect of electrode nanoarchitecture on the performance of electric double layer capacitor (EDLC) porous electrodes consisting of highly-ordered monodisperse spherical carbon nanoparticles. To do so, cyclic voltammograms, reproducing three-electrode measurements, were numerically generated for electrodes with diff...
Article
This study presents a theoretical framework developed from first principles for predicting the spatiotemporal thermal behavior of hybrid pseudocapacitors under galvanostatic cycling. It accounts for irreversible and reversible heat generation in the electrolyte and in the electrodes due to Joule heating, electric double layer (EDL) formation, and r...
Article
Water, under conditions of nanoscale confinement, exhibits anomalous dynamics, and enhanced thermal deformations, which may be further enhanced when nanoconfined water is in contact with hydrophilic interfaces. Such heightened thermal deformation of water could control the volume stability of hydrated materials with nano-confined structural water....