Lithium-ion battery (LIB) is widely utilized in many modern applications as energy sources. Numerous efforts have been dedicated to increasing electrochemical performances, but improvement on battery safety remains a visible challenge. While new electrode materials have been developed, advancement in new separator for LIB has remained relatively slow. Separator is the polymeric porous material that physically separates electrodes and allows free flow of ions through its structure. It is electrochemically inactive but essential for avoiding thermal runaway conditions. Besides its crucial functions, separator has been known as the mechanically weakest component. Structural battery is a new approach that employs multifunctional material concept to use LIB as load-bearing material to minimize the weight of the complete system and maximize the efficiency. Separator materials are required to have good thermal stability, battery chemistry, and mechanical performance. This work aims at creating electrospun membranes with improved thermal resistance, structural integrity and moderate ionic conductivity as the next generation LIB separators. Electrospinning process is known as a versatile and straightforward technique to fabricate continuous fibers at nano- and micro- scales. The electrospinning process employs an electrostatic force to control the production of fibers from polymer solutions. Solution and process parameters, including type of polymer and solvent system, concentration of polymer solution, acceleration voltage, and solution feed rate, have been studied to achieve the desirable membrane properties. In this report, the electrospinning parameters affecting morphology and corresponding properties of electrospun membranes, electrospun polymer composite and polymer-metal oxide composite membranes for structural battery applications will be discussed.

Indiana University-Purdue University Indianapolis (IUPUI) / This study proposes and evaluates a multi-functional carbon fiber reinforced composite with embedded Lithium-ion battery for its structural integrity concept. The comparison of versatile composite structures manufactured conventionally, air-sprayed and electrospun multi walled carbon nano tubes in order to discover a better packaging method for incorporating lithium-ion batteries at its core is determined. In the electrospinning process recognized globally as a flexible and cost-effective method for generating continuous Nano filaments. It was incorporated exactly on the prepreg surface to obtain effective inter-facial bonding and adhesion between the layers. The mechanical and physical properties of carbon fiber reinforced polymers (CFRP) with electrospun multi walled carbon nano tubes (CNTs) have evidenced to possess higher mechanical strength incorporated between the layers of the composite prepreg than the traditional CFRP prepreg composite, At the same time the air sprayed CFRP with CNTs offers mechanical strength more than the traditional CFRP prepreg but lesser than the electrospun. This can be a design consideration from the economic feasibility viewpoint. They also contribute to efficient load transfer and structural load bearing implementation without compromising the chemistry of battery. The design validation, manufacture methods, and experimental characterization (mechano-electrical) of Multi-functional energy storage composites (MESCs) are examined. Experimental results on the electrochemical characterization reveal that the MESCs show comparable performance to the standard lithium-ion pouch cells without any external packaging and not under any loading requirements. The mechanical performance of the MESC cells especially electrospun CFRP is evaluated from three-point bending tests with the results demonstrating significant mechanical strength and stiffness compared to traditional pouch cells and conventional, air-sprayed CFRP and at lowered packaging weight and thickness. This mechanical robustness of the MESCs enable them to be manufactured as energy-storage devices for electric vehicles.

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Kolfiber CF kan användas som positiv elektrod i strukturella batterier om de beläggs med ett aktivt material, såsom litiumjärnfosfat LFP. Fördelen med att använda kolfibrer som elektroder är att de samtidigt kan bära mekanisk belastning och lagra elektrisk energi. Det finns flera tekniker för att belägga kolfibrerna. I denna rapport kommer en jämförelse att göras av fibrer som belagts med elektroforetisk deponering, sprutbeläggning och pulverimpregnering. Elektrokemisk karakterisering kommer att avgöra och utvärdera prestandan hos dessa tre tekniker. Cellerna som monterades med sprutbeläggda och pulverimpregnerade prover visade de högsta kapaciteterna, 141 mAh/g vid C/10 respektive 139 mAh/g vid C/14. Vidare testning utfördes på de pulverimpregnerade proverna för att studera elektriska egenskaper och beteende, såsom elektrokemisk impedansspektroskopi EIS, cyklisk voltammetri CV och långtids-cykling. Svepelektronmikroskop SEM analys genomfördes för att observera ytmorfologin och förstå hur de elektrokemiska testerna kan påverka fibrernas yta. / Carbon Fibres (CF) can be used as the positive electrode in structural batteries if they are coated with an active material such as Lithium Iron Phosphate Oxide (LFP). The advantage of using carbon fibres as electrodes is that they simultaneously can carry the mechanical load and store electrical energy. There are several techniques to coat the carbon fibres. In this report, a comparison will be made on fibres coated using electrophoretic deposition, spray coating and powder impregnation. Electrochemical characterisation will determine and evaluate the performance of these three techniques. Cells assembled with spray-coated and powder-impregnated samples delivered the highest capacities, 141 mAh/g at C/10 and 139 mAh/g at C/14, respectively. Further testing was conducted on the powder-impregnated samples to study the electrical properties and behaviour, such as Electrochemical Impedance Spectroscopy (EIS), Cyclic Voltammetry (CV) and long-term cycling. Scanning Electron Microscopy (SEM) analysis was performed to see the surface morphology and understand how electrochemical testing can affect the surface of the fibres.

Strukturella batterier är multifunktionella; de tillhandahåller lagring av elektrokemisk energi samtidigt som de bidrar med en lastbärande funktion. Tillsammans möjliggör detta att batteriet kan integreras i karossen hos ett elektriskt fordon eller apparat. Denna multifunktionalitet möjliggör således en avsevärd reducering i fordonets vikt. Kompositmaterialet är förstärkt av kolfiberelektroder, innesluten i en elektrolytstruktur. För att förverkliga detta koncept måste batteriets elektrolyt kunna motstå mekanisk belastning, samtidigt som den transporterar joner mellan batteriets elektroder. Denna studie syftar till att bygga vidare på konceptet av fas-separerade polymerelektrolyter, skapade från polymerisationsinducerad fasseparation via termisk härdning, vilket är en teknik utvecklad av Schneider et al. och Ihrner et al. Vidare undersöks effekten av att dels använda en elektrolytlösning baserad på EC:PC, men även att inkorporera tioler till polymernätverket. Tvärbindningsmolekylerna som användes i denna studie inkluderade trimetylolpropan tris(3-merkaptopropionat) (3TMP), pentaerythritol tetrakis(3-merkaptopropionat) (4PER), och dipentaerythritol hexakis-(3-merkaptopropionat) (6DPER). Dessa skiljer sig i antal funktionella tiolgrupper. Konduktivitet, termo-mekanisk prestanda och strukturberoende egenskaper undersöktes genom tre laborativa faser. Den första fasen behandlade inverkan på elektrolytsystemet av ändrat lösningsmedel, tiol-funktionalitet samt tiolgruppförhållandet gentemot allyl gruppen på den primära monomeren. Sampolymeren innehållandes 6DPER uppvisade bäst multifunktionalitet, varpå denna utvecklades vidare i fas två där en optimal sammansättning fastställdes som bestod utav 45 viktprocent jonlösning. I den slutliga fasen konstruerades en halv-cell baserat på den tidigare optimerade elektrolytkompositionen; den uppmätta kapaciteten visar tydlig förbättring jämfört med tidigare forskning. Resultatet som erhölls i denna studie bidrar till förståendet av strukturella batteri-elektrolyter samt den forskning som en dag kan komma att förverkliga strukturella batterier och dess tillämpningskrav. / Structural batteries are multifunctional; providing electrochemical energy storage synergistically with a load-bearing function that enables their integration into the body panels of electric devices and vehicles. Thus, massless energy can be achieved. As a composite material, it is composed of reinforcing carbon fibre electrodes embedded in an electrolyte matrix. To realize this concept, the electrolyte must simultaneously transfer mechanical load and transport ions between electrodes. The following study builds on a phase-separated polymer electrolyte, created using polymerization-induced phase separation via thermal curing, formulated by Schneider et al. and Ihrner et al.. The impact of the incorporation of thiols for copolymerization and as cross-linking agents for the polymer network was researched along with use of an EC:PC-based solvent. The three thiols studied were: trimethylolpropane tris(3-mercaptopropionate) (3TMP), pentaerythritol tetrakis(3-mercaptopropionate) (4PER), and dipentaerythritol hexakis-(3-mercaptopropionate) (6DPER). These differed in regard to the amount of thiol functional groups present. Ionic conductivity, thermo-mechanical performance and structure-property relationships were studied across 3 laboratory phases. The first phase concerned the effect of thiol-functionality, the thiol functional group ratio relative to the allyl group present in the primary monomer, and the solvent interaction. 6DPER was concluded to be the most promising cross-linking agent. During the second phase, the effect of electrolyte content was evaluated with an optimum of 45 weight% determined. The third phase concluded the study, wherein a half-cell was assembled with the optimized electrolyte formulation showing improved capacity relative to previous studies. The results developed here contribute to the understanding of structural battery electrolyte systems and their continued research to meet application demands.