Structures For Lithium-ion Batteries Research Articles

Customizable 3D-printed decoupled structural lithium-ion batteries with stable cyclability and mechanical robustness

Structural batteries are considered one of the promising strategies for improving the endurance of electric vehicles. However, the trade-off between load-bearing capability and electrochemical performance remains a significant challenge. This paper proposes an efficient 3D printing-assisted fabrication strategy for high-performance structural batteries with customizable geometric configurations. The composite structural battery sample shows a bending modulus of 24.5 GPa, which could withstand maximum tensile stress and three-point bending stress of 155 MPa (specific tensile strength of 88340 N m kg−1) and 123 MPa (specific bending strength of 61553 N m kg−1). Meanwhile, it can achieve a high energy density of 120 Wh kg−1 and 210 Wh L−1 (3.5 mA cm−2) and superior capacity retention of up to 92 % after 500 cycles (10.5 mA cm−2). More importantly, the in-situ mechanical-electrochemical test demonstrates exceptional performance, retaining an ultra-high capacity of 98.7 % under a tensile stress of 80 MPa, and maintaining a capacity retention rate of 97 % with an average capacity decay per cycle of only 0.18 % under a bending stress of 96.3 MPa. In addition, finite element analysis is also used to verify the failure mechanism of the battery under bending load. Meanwhile, the fabricated structural battery can be applied to autonomous mobile robots, showing the multifunction energy storage and load-bearing. As a result, this work showcases the great potential of incorporating high-performance structural batteries into engineering applications such as small-scale warehousing, logistics equipment, and intelligent robotics.

Combining 3D printing of copper current collectors and electrophoretic deposition of electrode materials for structural lithium-ion batteries

Combining 3D printing of copper current collectors and electrophoretic deposition of electrode materials for structural lithium-ion batteries

Electro‐chemo‐mechanical modeling of structural battery electrode materials

AbstractIn this paper, a linear electro‐chemo‐mechanical model for a structural Lithium ion battery electrode material is presented. The considered material is composed of particles (storing Lithium) embedded in a porous polymer matrix. The pores are filled with a liquid electrolyte. In this three phase material different processes are taken into account: ion diffusion and migration inside the electrolyte, Lithium diffusion inside the particles, electric current inside the binder matrix and particles as well as deformation in these two phases. After presenting the mathematical model, we perform a numerical study of a simple system to investigate the model behavior.

High performance shape-adjustable structural lithium-ion battery based on hybrid fiber reinforced epoxy composite

High performance shape-adjustable structural batteries with both excellent electrochemical performances and mechanical properties, and compatible with conventional batteries and composite processing techniques, are highly attractive for next generation electrical vehicles and electrical aircrafts. Herein, a high-performance structural lithium-ion battery composite (SLBC) is developed by encapsulating commercial-available battery core materials with hybrid fiber reinforced epoxy composite laminate shells, which can be assembled into desired irregular shapes with the conventional vacuum bagging technique. Firstly, the laminate shell layout with the combination of glass fiber woven fabric (GFWF) and carbon fiber woven fabric (CFWF) is designed and optimized. Meanwhile, a PET film is employed to wrap the battery core materials, which enables processing of the SLBC with liquid electrolyte in ambient condition. The SLBC obtained demonstrates both prominent mechanical (flexural strength of 211.7 MPa and flexural modulus of 7.7 GPa) and electrochemical properties (an initial discharge capacity of 98.5 mAh/g at 0.2C, a high energy density of 314.5 Wh kg−1, and a good cycling performance) owing to the hybrid design of CFWF and GFWF as well as a sealed environment to guarantee the battery operate well. Impressively, the in-situ mechano-electrochemical measurements are assessed under the out-of-plane compressive stress and the flexural stress conditions. These results show that the SLBC under loading can maintain stable electrochemical performance even at a high out-of-plane compressive stress of 20 MPa and a high flexural stress of 150 MPa. Furthermore, the SLBC can also maintain the excellent discharge capacity when subjected to a high impact energy, which is promising in next generation electrical vehicles. Finally, the wave-like SLBC fabricated demonstrates the effectiveness in withstanding loads and driving electric fan simultaneously, which is promising in next generation electrical vehicles..

Dip-Coating of Carbon Fibers for the Development of Lithium Iron Phosphate Electrodes for Structural Lithium-Ion Batteries

This study describes a dip-coating method for applying an active material to commercially available intermediate modulus carbon fibers (CFs). A suite of tools were developed to assist with the handling and coating of CF tows to create disc electrodes. CF electrodes were fitted into 2025-type coin cells, for electrochemical analysis, first to determine their performance as anodes. Specimens of CFs were dip-coated with a slurry consisting of lithium iron phosphate, carbon black, and polyvinylidene fluoride, then dried, and fitted into half-cells to analyze the cathode performance. A cyclic voltammetry sweep was performed on each half-cell to determine suitable cycling potential limits, followed by galvanostatic cycling for a minimum of 30 cycles. Measured capacities for anode and cathode half-cells yielded 92 and 52.3 A h kg–1, respectively. A full-cell with CFs in both electrodes was assembled and tested, revealing a capacity of 24.7 A h kg–1 after 30 cycles. Finally, both the anode and cathode were examined with a scanning electron microscope to establish a benchmark (anode) to compare surface topologies and to analyze the quality of the active material applied via dip-coating (cathode).

Fiber metal laminated structural batteries with multifunctional solid polymer electrolytes

A structural lithium ion battery is a material that can carry load and simultaneously be used to store electrical energy. We propose for the first time the fabrication of structural batteries based on modified fiber metal laminates with integrated energy storage function. The metal sheets act as both an impact resisting layer and current collectors. With the successful fabrication of solid polymer electrolyte membrane of high ionic conductivity, metal sheets supported solid state battery core can be integrated with fiber reinforced polymer composites (FRP) by layer stacking and subsequent co-curing to produce lightweight fiber metal laminated structural battery (FMLSB), which has outstanding impact resistance and can still operate a LED when subjected to 30 J impact energy. Further analysis indicates the underlying mechanism lies in low energy adsorption for FRP incorporated with metal sheets supported solid state battery core, which only brings about divergent in-plane cracks to FMLSB, in contrast to through-thickness penetration of FRP. To prove the concept of the as-fabricated FMLSB in electric vehicle industry, we successfully fabricated an 11 mAh FMLSB-type chassis which can be self-powered for over 20 min. This study shows that fiber metal laminates combined with solid state battery represents a promising path to mechanically strong structural batteries.

Quantitative characterisation of the layered structure within lithium-ion batteries using ultrasonic resonance

Lithium-ion batteries (LIBs) are becoming an important energy storage solution to achieve carbon neutrality, but it remains challenging to characterise their internal states for the assurance of performance, durability and safety. This work reports a simple but powerful non-destructive characterisation technique, based on the formation of ultrasonic resonance from the repetitive layers within LIBs. A physical model is developed from the ground up, to interpret the results from standard experimental ultrasonic measurement setups. As output, the method delivers a range of critical pieces of information about the inner structure of LIBs, such as the number of layers, the average thicknesses of electrodes, the image of internal layers, and the states of charge variations across individual layers. This enables the quantitative tracking of internal cell properties, potentially providing new means of quality control during production processes, and tracking the states of health and charge during operation.

Electrical control of ON–OFF magnetism and exchange bias via reversible ionic motion

The lithium-based magneto-ionic effect is an emerging and promising way to control magnetism. Here, a lithium-ion battery-structure is adopted to control the magnetic properties of the Co/CoO bilayer. Using operando magnetometry, we performed a reversible toggling of lithium ion induced magnetic phase transition between nano-Co (superparamagnetism) and CoO (antiferromagnetism), which enables an ON–OFF magnetism switching. On this basis, a robust modulation of exchange bias by electric field at low temperature is achieved. In addition, reversible tuning of coercivity and magnetization up to 71% and 118%, respectively, in a Co/CoO bilayer at room temperature are performed. This work provides a more efficient means to modulate antiferromagnetism and exchange bias, facilitating the development of antiferromagnetic spintronics.

Structural Lithium-Ion Battery Cathodes and Anodes Based on Branched Aramid Nanofibers.

Structural batteries and supercapacitors combine energy storage and structural functionalities in a single unit, leading to lighter and more efficient electric vehicles. However, conventional electrodes for batteries and supercapacitors are optimized for high energy storage and suffer from poor mechanical properties. More specifically, commercial lithium-ion battery anodes and cathodes demonstrate tensile strength values <4 MPa and Young's modulus of <1 GPa. Here, we show that using branched aramid nanofibers (BANFs) or nanoscale Kevlar fibers as a binder leads to mechanically stronger lithium-ion battery electrodes. BANFs are combined with lithium iron phosphate (LFP, cathode) or silicon (Si, anode) particles and reduced graphene oxide (rGO). Hydrogen-bonding interactions between rGO and BANFs are harnessed to accommodate load transfer within the nanocomposite electrodes. Overall, we obtained up to 2 orders of magnitude improvements in Young's modulus and tensile strength compared to commercial battery electrodes while maintaining good energy storage capabilities. This work demonstrates an efficient route for designing structural lithium-ion battery cathodes and anodes with enhanced mechanical properties using BANFs as a binder.

Electrophoretic coating of LiFePO4/Graphene oxide on carbon fibers as cathode electrodes for structural lithium ion batteries

Carbon fibers (CF), commonly used in the structure of airplanes or cars, can also work as conductive electrodes in “structural batteries” for distributed energy storage. To this aim CF should be chemically functionalized, which is challenging due to their complex geometry and surface. Here, we describe an “all-electrostatic” approach taking advantage of the intrinsic conductivity of CF to coat them with a cathode material composed of LiFePO4 blended with nanosheets of electrochemically exfoliated graphene oxide (EGO). We first achieve electrostatic self-assembly of the nanometric components at the nanoscale, then use Electrophoretic Deposition (EPD) to obtain a uniform, macroscale coating on the fibers. We achieve a LiFePO4 loading >90 wt% featuring good adhesion on the carbon fibers, low degradation upon battery cycling, low charge transfer resistance. The electrode composite outperforms similar state-of-the-art cathode materials when used in Half-Cell vs. Li. Full battery cells using coated CF as cathode and pristine CF as anode yield specific energy density of 222.14 Wh⋅kg−1 and power density of 0.29 kW⋅kg−1 with 88.1% capacity retention at 1 C over 300 cycles, compatible with industrial applications of this technique in composites production.

Tubular laminated composite structural battery

This paper introduces a polymer-matrix composite-based structural lithium-ion battery system with tubular morphology. Its shape and closed cross-section, fabricated during the autoclave process, allow for high electrochemical performance by controlling the electrode distance and battery environment. To prevent the degradation of the organic liquid electrolyte within this continuous resin polymer system, extra components such as thermoplastic hot melt film, a double glass load-bearing separator, aluminum film, and polydimethylsiloxane were implanted. The electrochemical properties of this manufactured multi-functional structural battery design, named the tubular laminated composite battery (TLCB), were tested with a galvanic cell testing machine. The initial specific capacity of TLCB was found to be approximately 120–130 mAh/g with good cycling performance and steady coulombic efficiency. Furthermore, mechanical load resistance and correlation with electrochemical performance were also assessed under the four-point bending load condition. These results show that the TLCB has the potential to operate as a subsidiary energy storage for future electric vehicle systems with a certain level of structural specific capacity and load-bearing properties.

Cylindrical Lithium-Ion Structural Batteries for Drones

The increasing use of battery-powered multirotor aircraft for industrial applications has allowed for advancements in a wide range of fields. These aircraft, however, have limited payloads and shorter endurance and range than fuel-powered conventional aircraft. To extend these key performance metrics, we have developed an optimized structural battery that uses commercially available battery cells as load bearing and power source elements for weight critical applications. Multifunctional lithium-based batteries have been previously proposed for the efficient use of space and mass in electric vehicles [1]. Lithium batteries offer an energy density high enough for most small multirotor flight applications [2], however these batteries often constitute a significant portion of the aircraft’s mass. This implementation is proposed to decrease the structural frame mass and thus increase multirotor performance characteristics such as payload capacity and flight time [3].In this work, structural lithium-ion batteries were integrated into the design of a commercial drone to improve hover time. Hover tests were first performed with the original lithium polymer batteries for comparison purposes. Battery voltage was measured every 2 minutes to monitor voltage decrease versus hover time. With no payload, the original hover time of the drone was 34 minutes. For payloads of 0.5, 1.0, and 1.5 kg, hover times decreased to 28.7, 22.7, and 19.1 minutes, respectively. Standard 18650 cylindrical battery cells (Panasonic NCR18650B) were then integrated into the carbon fiber arms of the drone, to replace the original lithium polymer batteries. This design modification reduced the weight of the drone from 1242 g to 848 g, while also improving the structural integrity of the carbon fiber arms. For both designs, the velocity of the drone was related to the impact force experienced in the case of a crash. The carbon fiber arms would fracture at 4 m/s when hollow, and 7 m/s when reinforced with lithium-ion batteries. Hover tests for this modified design are being performed currently, and times are expected to be on the order of 40% longer [4]. Ongoing efforts to investigate the relationship between the intensity of power usage and the angular inertia of the drone will help to characterize the optimal battery distribution.[1] Zhang YC, Ma J, Singh AK, et al. (2017) Multifunctional structural lithium-ion battery for electric vehicles. Journal of Intelligent Material Systems and Structures 28: 1603-1613.[2] Vikstrom, H.; Davidsson, S.; Hook, M., Lithium availability and future production outlooks. Applied Energy 2013, 110, 252-266.[3] Dughir, C.; Ieee, Power wire thickness influence on the multicopters flight time. 2016 12th Ieee International Symposium on Electronics and Telecommunications (Isetc'16) 2016, 239-242.[4] Hollinger AS, McAnallen DR, Brockett MT, DeLaney SC, Ma J, Rahn CD. Cylindrical lithium‐ion structural batteries for drones. International Journal of Energy Research. 2020; 44:560–566. Figure 1

Synthesis of one-dimensional PAN-based carbon fiber/NiO composite as an anode material for structural lithium-ion batteries

The devices with high energy storage such as structural lithium-ion batteries (SLIBs) have recently attracted extensive attention, and many efforts have been made to prepare the high-performance anodes. Polyacrylonitrile (PAN)-based carbon fiber with light weight can save volume and quality, which has been recognized as a promising anode material for structural lithium-ion batteries (SLIBs). Herein, we successfully developed a one-dimensional PAN-based carbon fiber/NiO composite (CF/NiO) through an easy and convenient method. Benefiting from the combination of high theoretical specific capacity and high electrical conductivity of NiO (~ 780 mAh g−1) and strong mechanical properties of carbon fiber, the resulting CF/NiO exhibits excellent performance in lithium-ion storage. CF/NiO composite presents a coulombic efficiency of over 99% and good cyclic ability. It performs a high reversible capacity of 648 mAh g−1 after 150 cycles at a current density of 100 mA g−1, approximately 2.5 times as high as the pure CF (~ 260 mAh g−1). The excellent electrochemical performance can be attributed to the synergistic effect between the one-dimensional structural carbon fiber and NiO, making the electrochemical reaction highly reversible.

Fabrication and multiphysics modeling of modified carbon fiber as structural anodes for lithium-ion batteries

The structural battery is a type of multifunctional battery that possesses energy storage and load-bearing capability simultaneously. Carbon fibers (CFs) serve as promising electrode materials used in structural batteries. However, most of the structural batteries and the corresponding component materials are fabricated unguided due to the lack of a full understanding of the multiphysics nature. Herein, we fabricated surface-modified CFs and investigated the electro-chemo-mechanical behaviors of the structural lithium-ion battery through a multiphysics modeling methodology. A two-dimensional multiphysics model is established by detail description of anode, cathode, separator, and electrolyte. The model is then validated comprehensively by the testing data from the fabricated cells with modified CFs as electrodes. We discover that with the higher volume fraction of modified CFs, the battery capacity increases without deteriorating the stress status; meanwhile, independently increasing the ratio of the modified layer on CFs leads to a higher specific capacity but lower stiffness. With the appropriate ratio of the modified layer controlled during fabrication, the modified CFs can achieve a specific capacity of 216 mA h/g and tensile stiffness of 138.8 GPa. Results provide theoretical insights for understanding the multiphysics nature and powerful modeling tool to the design of next-generation structural batteries.

Polymer reinforced carbon fiber interfaces for high energy density structural lithium-ion batteries

Interface engineering enables a practical multifunctional advantage in a structural battery.

Performance of Carbon Fibers with Various Coatings in Composite Lithium-Ion Structural Batteries

Traditional Lithium-ion batteries (LIBs) are dominating the battery market where the energy density is very important. However, there is still potential for improvements. Normally, around 60% of the total cell is the active material whereas the rest is the weight of current collectors, casing, additives, etc [1].The structural battery concept was first introduced in 2004 by Wetzel et.al [2]. It is a multifunctional battery that can carry the load while storing the energy and therefore reduce the overall weight of a mobile electric device. Carbon fibers (CFs) are convenient for structural batteries due to their good electrical, electrochemical and mechanical properties [1]. It has been shown that carbon fibers can reversibly insert lithium ions with a capacity up to 350 mAh g-1 which is comparable to graphite (372 mAh g-1) [1]. Moreover, the electrical conductivity of the carbon fibers can reach around 1000 S cm-1 which allows the carbon fibers to be used without current collectors [1]. Removing current collectors and additives from the total structure and introducing carbon fibers into LIBs decreases the non-active mass as well as providing mechanical stability to the system. In a composite material, a bulk phase (polymer/matrix) encases the reinforcing phase which is carbon fiber in the structural battery. Polymer matrix holds the carbon fibers together and transfers the loads to fibers, while carbon fibers carry the load. A structural battery electrolyte (SBE) was developed at KTH as a load carrying polymer matrix that simultaneously conduct ions [3]. In Figure 1, the upper lamina corresponds to the negative electrode where the SBE is reinforced with carbon fibers. In the lower lamina SBE is reinforced with carbon fibers that are coated with a positive electrode material (e.g. LiFePO4). Carbon fibers in the negative lamina and the coated carbon fibers in the positive lamina are the active materials separated by a thin separator. The positive electrode is a challenge as carbon fibers need a coating with active material that adhere well to the carbon fibers. Obtaining an evenly distributed coating of positive electrode particles effects the mechanical performance of the structural battery. An excessive amount of active material coating will lower the fiber volume fraction in a structural battery and can decrease its mechanical properties whereas it would enhance the energy density. In this work, we present different coating techniques in order to make a structural positive electrode in a laminated structural battery. Accordingly, electrophoretic deposition (EPD), direct-ink writing (DIW), slurry casting and vacuum assisted slurry infusion methods are investigated individually. As it is important to have evenly coated single fibers within a tow, an even current distribution within the EPD cell is of high importance. A specific EPD cell is designed for this aim and it is used to coat carbon fibers electrochemically and uniformly. This new cell design gives the flexibility to obtain the electrochemical parameters (distance, coating thickness, current distribution, etc.) to encase the fibers in a tow homogeneously and hence, several micrometers of coating thickness can be obtained. Direct-ink writing on the carbon fibers is first shown here as a coating method. A specific ink is formulated to coat the fibers with the positive electrode material and used in a modified ink-printer with a specifically designed nozzle. Rheology of the ink and the coating speed is controlled in accordance with the coating quality. Slurry casting as a traditional method in LIBs is also investigated on fibers via doctor blade coating. The same ink is used in vacuum-assisted slurry infusion. The carbon fibers with various coatings are analyzed using surface morphology (SEM), electrochemical and mechanical tests in order to investigate the performance of the coated fibers in a laminated battery. Figure 1. Schematic illustration of laminated structural battery References Hagberg. Carbon Fibres for Multifunctional Lithium-Ion Batteries, Doctoral Thesis. KTH Royal Institute of Technology, Stockholm, Sweden, 2018.Wetzel. Multifunctional Composites for Future Energy Storage in Aerospace Structures. Communications, and Structure. AMPITAC Q. 8 (2004), 91-95. Ihrner, W. Johannisson, F. Sieland, D. Zenkert and M. Johansson. Structural lithium ion battery electrolytes: Via reaction induced phase-separation. Journal of Material Chemistry A 5.48 (2017), 25652-25659. Figure 1

Carbon fiber reinforced structural lithium-ion battery composite: Multifunctional power integration for CubeSats

Here we demonstrate a multifunctional battery platform where lithium-ion battery active materials are combined with carbon fiber weave materials to form energy storage composites using traditional layup methods. This design utilizes epoxy resin as a packaging medium for the battery and the carbon fibers as both a conductive current collector and structurally reinforcing layer. These composites exhibit energy density surpassing 35 Wh/kg relative to combined active and inactive composite materials, stable full-cell cycling, and mechanical properties including tensile strength of 213 MPa and Young’s modulus of ~1.8 MPa/(Δl/l). Structural battery panels developed from this approach are demonstrated as an integrated power delivery platform for a 1U CubeSat frame to augment or replace interior external battery packs. Overall, this approach shows a new path for battery integration into systems where the inactive materials for energy storage are the active composite structural materials.

Preparation of PAN-based carbon fiber/Co3O4 composite and potential application in structural lithium-ion battery anodes

Lightweight polyacrylonitrile (PAN)-based carbon fiber can give volume and mass savings, which has been considered as a promising anode material for structural lithium-ion batteries (SLIBs). However, the current issue is the limitation of low capacity. To improve the situation, a novel PAN-based carbon fiber/Co3O4 composite (CF/Co3O4) has been developed through a chemical deposition method. Since combining advantage of high theoretical specific capacity of Co3O4 and great electroconductivity as well as strong mechanical of carbon fiber, the prepared CF/Co3O4 shows excellent performances as an anode material for SLIBs. It presents a coulombic efficiency of over 99% and stable cyclic ability. Even if the number of cycles reaches to 150, a steady discharge reversible capacity up to 625 mAh g−1 can be retained, approximately 2.7 times as much as pure CF (~ 230 mAh g−1). The improved cycling stability of CF/Co3O4 can be owed to the interactions between CF and Co3O4 anchored on the CF. Furthermore, a solid polymer electrolyte was also prepared with the flexibility, which shows a steady discharge reversible capacity of 500 mAh g−1 at 100 mA g−1. The paper provides an affordable method to solve the problem of the limitation of capacity in current SLIBs when using commercial carbon fibers as anode materials.

Preparation of PAN-based carbon fiber@MnO2 composite as an anode material for structural lithium-ion batteries

Carbon fiber@MnO2 composite (CF@MnO2) has been successfully synthesized based on the redox mechanism, and the morphological and electrochemical features are also studied. As a promising anode material for structural lithium-ion batteries (SLIBs), CF@MnO2 composite presents a coulombic efficiency of over 99% and good cyclic ability. It performs a high reversible capacity of 648 mAh g−1 after 150 cycles at a current density of 100 mA g−1, approximately 2.5 times as high as the pure CF (~ 260 mAh g−1). Moreover, the images of attained composite after the cycle show the fibrous structure do not change much, which verifies it retains good cycle stability. The superior electrochemical performance of the CF@MnO2 composite can be attributed to the unique hierarchy architecture and the synergistic effect between MnO2 and CF, which can effectively alleviate the volume expansion of MnO2 during the lithium insertion/extraction.

Bicontinuous Electrolytes via Thermally Initiated Polymerization for Structural Lithium Ion Batteries

Structural batteries (SBs) are a growing research subject worldwide. The idea is to provide massless energy by using a multifunctional material. This technology can provide a new pathway in electri ...