Portable Consumer Electronics Research Articles

(Invited) Solvometallurgy as a Sustainable Approach for Lithium-Ion Batteries Recycling

Lithium-Ion Batteries, LIBs, are the core devices that made possible the diffusion of portable consumer electronics and, more recently, the booming of the electric vehicle market. [1] Their ubiquitous use and diffusion led to the well-known and urgent problem of spent LIBs management. Indeed, spent LIBs represent a complex and hazardous kind of waste for which specific regulation, disposal, and recycling routes are still missing. At the same time the continuous and growing production of LIBs involves the mandatory use of specific elements such as Li, Co, Ni, Cu, Al that are considered strategic or critical raw materials due to their limited availability, high costs, monopoly, and geological distribution. [2] The development of efficient and sustainable procedures for recycling of spent LIBs is the answer to these two main challenges as in enable to properly manage the LIBs waste and allow for the recovery of critical raw materials. While at industrial scale the high temperature pyrometallurgy and hydrometallurgy are the methods in use today, in the very last years, many approaches have been explored at research level, among them low temperature pyrometallurgy, soft hydrometallurgy, solvometallurgy, bioleaching. [3] Among them, the solvometallurgical approach exploiting Deep Eutectic Solvents (DESs) as leaching agents is particularly appealing thank to some specific features such as the low volatility, low flammability, low costs, ease of preparation combined with high leaching efficiencies.DESs are mixture of based on the presence of a hydrogen bond donors and acceptors forming a eutectic mixture at ambient temperature; although their first conceptualization is recent, several compositions have been already appeared in literature for this specific application. [4] At the same time, a rationalization of the role of the mixture components and a specific design of the composition, tailored for the application in LIBs recycling is still missing. We here present the results of our work on the development of new DESs compositions enabling the close-loop recycling of different spent cathodes. The DES compositions have been designed considering the overall recycling process, the effect of the DES compositions in terms of hydrogen bond donors and acceptors has been evaluated and rationalized through a preliminary chemical-physical characterization through thermal, NMR, FTIR, viscosity analysis. The leaching of the most common cathode has been optimized against the dominant parameters (temperature, treatment duration, cathode-to-DES ratio) opening the ways for two possibilities: the recovery of critical raw materials and the direct resynthesis of new cathodes. All the steps and products have been fully characterized with a multi-technique approach including structural and chemical investigation through the electrochemical testing of the re-synthetized materials. Finally, these two options have been assessed through LCA analysis, being able to provide an overview of the global sustainability of the proposed processes.[1] Ji et al., Chem Soc. Rev. (2023) doi 10.1039/d3cs00254c[2] Global Supply Chains of EV Batteries report, International Energy Agency[3] Yasa et al. J. En. Stor. 73 (2023) 109073[4] Padwal et al. Adv. En. Sus. Res. 3 (2022) 2100133

Three-dimensional high-aspect-ratio microarray thick electrodes for high-rate hybrid supercapacitors

Hybrid supercapacitors (HSCs) with facile integration and high process compatibility are considered ideal power sources for portable consumer electronics. However, as a crucial component for storing energy, traditional thin-film electrodes exhibit low energy density. Although increasing the thickness of thin films can enhance the energy density of the electrodes, it gives rise to issues such as poor mechanical stability and long electron/ion transport pathways. Constructing a stable three-dimensional (3D) ordered thick electrode is considered the key to addressing the aforementioned contradictions. In this work, a manufacturing process combining lithography and chemical deposition techniques is developed to produce large-area and high-aspect-ratio 3D nickel ordered cylindrical array (NiOCA) current collectors. Positive electrodes loaded with nickel–cobalt bimetallic hydroxide (NiOCA/NiCo-LDH) are constructed by electrodeposition, and HSCs are assembled with NiOCA/nitrogen-doped porous carbon (NiOCA/NPC) as negative electrodes. The HSCs exhibits 55% capacity retention with the current density ranging from 2 to 50 mA cm−2. Moreover, it maintains 98.2% of the initial capacity after long-term cycling of 15,000 cycles at a current density of 10 mA cm−2. The manufacturing process demonstrates customizability and favorable repeatability. It is anticipated to provide innovative concepts for the large-scale production of 3D microarray thick electrodes for high-performance energy storage system.

Wireless Power Transfer: Principles and Applications [Book News

The book gives a comprehensive view of wireless power transfer (WPT) technologies, with a special emphasis on the multiple-pickup WPT. A number of applications is also described, including the systems employed in portable consumer electronics, in‐flight charging for unmanned aerial vehicles, underwater wireless charging, and the high‐power electrical vehicle (EV) wireless charging that has been already mentioned above. The book is organized in four parts, each one of them consisting of multiple chapters. The first part is divided into two chapters: an overview of several WPT technologies is given, but the main emphasis is given to inductive power transfer (IPT) technology. The second part of the book gives a view of the issues related to the design and optimization of coupled coils and power circuits.

COMPARISON ON STUDY OF LITHIUM ION AND LEAD ACID CHARGING AND DISCHARGING CHARACTERISTICS

A lithium-ion or Li-ion battery is a type of rechargeable battery which uses the reversible reduction of lithium ions to store energy. It is the predominant battery type used in portable consumer electronics and electric vehicles. Energy density: 250–693 Wh/L (0.90–2.49 MJ/L) Specific energy: 100–265 Wh/kg (0.360–0.954 MJ/kg) Charge/discharge efficiency: 80–90% Cycle durability: 400–1,200 cycles Self-discharge rate: 0.35% to 2.5% per month depending on state of charge Specific power: c. 250–340 W/kg Lithium batteries, as opposed to alkaline, are capable of giving off a strong energy surge after a long period of low discharge. This makes them ideal for fire alarms. Alkaline batteries provide good, long-term power, but they lose strength over time. On the other side , the Lead acid battery are inexpensive compared to newer technologies, lead–acid batteries are widely used even when surge current is not important and other designs could provide higher energy densities. Energy density: 80–90 Wh/L Nominal cell voltage: 2.1 V Self-discharge rate: 3%–20%/month Specific energy: 35–40 Wh/kg Charge temperature interval: Min. −35°C, max. 45°C Charge/discharge efficiency: 50%–95% Cycle durability: <350 cycle In order to observe the characteristic nature of Lead acid & Lithium ion battery , a review is made on the subject using Matlab Simulink and Simscape.

Carbon Nanomaterials‐Enabled High‐Performance Supercapacitors: A Review

Supercapacitors (SCs), an important kind of electrochemical energy storage device, are featured with high power density, rapid charging and discharging, and ultralong cycling lifespan and have been widely applied in multiscenario energy storage and output systems, such as portable consumer electronics, electric vehicles, and reservoir setups for green and sustainable energy resources. Among their components, electrode materials are of primary importance in dictating their performances. Owing to good electric conductivity, achievably large specific surface area, low cost, chemical stability, and easy loading with other electrochemically active species, various carbon nanomaterials, including activated carbons, carbon nanotubes, graphene, and other porous carbons, are promising electrode materials in the fabrication of high‐performance SCs. In fact, the past decade has witnessed enormous efforts in the development of high‐performance carbon‐based SC electrode materials and great progresses achieved in the field. In this review, recent advances on these carbon‐based SCs are summarized through a number of selected representative works. In each one, the unique preparation method, structural features, and their correlations to electrochemical properties and final SC performance are presented and discussed. At the end of the review, the challenges and future developing prospects are briefly outlined.

Flexible freestanding conductive nanopaper based on PPy:PSS nanocellulose composite for supercapacitors with high performance

A freestanding, binder-free flexible polypyrrole: polystyrene sulfonate/cellulose nanopaper (PPy:PSS/CNP) electrode is successfully fabricated by a low-cost, simple, and fast vacuum filtration method for the first time. The hierarchical structure of CNP with high surface area and good mechanical strength not only provides a high electroactive region and shortens the diffusion distance of electrolyte ions, but also mitigates the volumetric expansion/shrinkage of the PPy during the charging/discharging process. The optimized PPy:PSS/CNP exhibits a high areal specific capacitance of 3.8 F cm−2 (corresponding to 475 F cm−3 and 240 F g−1) at 10 mV s−1 and good cycling stability (80.9% capacitance retention after 5000 cycles). The cyclic voltammetry curves of PPy:PSS/CNP at different bending angles indicate prominent flexibility and electrochemical stability of the electrode. Moreover, a symmetric supercapacitor device is assembled and delivers a high areal energy density of 122 µ cm−2 (15 W h cm−3) at a power density of 4.4 mW cm−2 (550 mW cm−3), which is superior to other cellulose-based materials. The combination of high supercapacitive performance, flexibility, easy fabrication, and cheapness of the PPy: PSS/CNP electrodes offers great potential for developing the next generation of green and economical portable and wearable consumer electronics.

Lithium-ion battery module-to-cell: disassembly and material analysis

Lithium-ion batteries (LIBs) are one of the most popular energy storage systems. Due to their excellent performance, they are widely used in portable consumer electronics and electric vehicles (EVs). The ever-increasing requirements for global carbon dioxide CO2 emission reduction inhibit the production of new combustion vehicles. Thus, the demand for EVs increases, as well as the number of spent LIBs. Due to increases in raw materials saving and reduction in energy and environmental impacts, recycling is one of the most promising solutions for end-of-life (EOL) treatment for spent LIBs. This work describes the first step in recycling the LIBs nickel-manganese-cobalt (NMC) based module from a full battery electric vehicle (BEV) holding its high recycling efficiency and considering the process costs and environmental impact. This paper is devoted to module-to-cell disassembly, discharge state characterization measurements, and material analysis of its components based on x-ray fluorescence (XRF) and diffraction (XRD).

Effect of Two Dimensional Additives on the Charge Storage Performance of All Solid-State Carbon Nanotube Based Flexible Supercapacitors.

Flexible and miniaturized electronic devices have attracted widespread attention due to their potential for future hand-held, portable consumer, and wearable electronics. This has incited a growing interest in the development of compact yet efficient power sources that are flexible and holds the potential to be implemented in confined space for newer applications. In the present work, we report the CNT (Carbon NanoTubes) buckypaper integrated with electroactive 2D materials such as graphene, graphene oxide (GO), and the transition metal sulphides (TMDs) especially, tin sulphide (SnS2). The flexible and free-standing, interface-enhanced CNT paper having homogeneously dispersed 2D materials was prepared using a traditional scalable casting method. The hybridized CNT films were thoroughly characterized to elucidate their structural and surface properties. Finally, such hybrid CNT films were used as, free-standing electrodes without any binder for the fabrication of flexible-solid-state supercapacitor (FSSSs) devices. In the FSSS, the electrochemical interactions between hybrid CNT paper electrodes and polymer gel electrolyte were studied. In the symmetric configuration, the CNT-SnS2 electrodes reach the highest areal and volumetric capacitance, and almost 4 times that of pristine CNT electrodes, whereas CNT-GO-based electrodes display high-rate capability. The CNT-SnS2-based symmetric FSSS devices exhibit an extended voltage window of 1.5 V with a high capacitance of 133 mF/cm2 and show high cyclic stability for 5000 cycles under 180 ⁰ bending.

A Review on the Molecular Modeling of Argyrodite Electrolytes for All-Solid-State Lithium Batteries

Solid-state argyrodite electrolytes are promising candidate materials to produce safe all-solid-state lithium batteries (ASSLBs) due to their high ionic conductivity. These batteries can be used to power electric vehicles and portable consumer electronics which need high power density. Atomic-scale modeling with ab initio calculations became an invaluable tool to better understand the intrinsic properties and stability of these materials. It is also used to create new structures to tailor their properties. This review article presents some of the recent theoretical investigations based on atomic-scale modeling to study argyrodite electrolytes for ASSLBs. A comparison of the effectiveness of argyrodite materials used for ASSLBs and the underlying advantages and disadvantages of the argyrodite materials are also presented in this article.

Design and Control of Ultra-High-Speed Sensorless Drive with Two-Input Power Source for Portable Consumer Electronics

The convenience and usability of portable consumer electronics that require a motor, such as vacuum cleaners and hair dryers, will be greatly improved if both ac and dc two-input power sources can be used. The dc input power is mostly composed of a dc battery, and single-phase voltage is used as ac input power. A converter system capable of converting ac and dc voltage with control technology is required to supply the voltage for motor driving to apply both ac and dc input to the product. Because a limited number of batteries are used to decrease the weight and size of portable products, a system such as a dc converter is necessary to supply the voltage required to operate the motor and to keep the voltage fluctuation according to the usage time constant. When ac power is used in the product, a voltage drop system that can step down the ac voltage to supply voltage to the dc link is necessary to supply the voltage required to operate the motor to the dc-link. In addition, it is important to reduce the size of the system through ultra-high-speed motor operation by increasing the rotation speed because portable consumer electronics that include a motor drive should be light and portable. This paper proposed a system that can supply a stable dc-link voltage required for ultra-high-speed motor control by applying a phase control method to the ac input side and a dc boost converter to the dc input side. Furthermore, the 1-shunt sensorless method was applied to the inverter for ultra-high-speed motor design and ultra-high-speed motor control system that contributes to product miniaturization and material cost reduction, experimental verification. The ultra-high-speed motor driving evaluation under ac and dc input power conditions and the conversion to dc power input when ac power interrupt occurs were performed to more stably verify the system according to the input power change.

Tunable Size of Hierarchically Porous Alumina Ceramics Based on DIW 3D Printing Supramolecular Gel.

A new three-dimensional (3D) printing gel is developed to construct hierarchically porous ceramics with adjustable millimeter-, micrometer-, and nanometer-scale size for application in thermal management. Not only does the gel based on supramolecular micelles exhibit excellent DIW 3D printability but also the supramolecular micelles act as templates that can precisely control the structure of micrometer-scale pores. The effect of millimeter- and μmicrometer-scale size on properties of porous ceramics is investigated in detail. The 3D-printed ceramic foam with millimeter-scale pores and smaller micrometer-scale pores shows better thermal insulation and lower compressive strength. For the thermal insulation, the local temperature of a chip exposed to contact heat is only 34.2 °C in the presence of a printed foam cap with a pore size of 41.5 μm, while the local temperature is 54.8 °C in the absence of the printed foam cap. The study provides a new method to construct hierarchically porous alumina ceramics with precisely tunable size, avoiding the issues of subtractive manufacturing and opening up new applications in portable devices or consumer electronics.

Optical metasurfaces for generating and manipulating optical vortex beams

Abstract Optical vortices (OVs) carrying orbital angular momentum (OAM) have attracted considerable interest in the field of optics and photonics owing to their peculiar optical features and extra degree of freedom for carrying information. Although there have been significant efforts to realize OVs using conventional optics, it is limited by large volume, high cost, and lack of design flexibility. Optical metasurfaces have recently attracted tremendous interest due to their unprecedented capability in the manipulation of the amplitude, phase, polarization, and frequency of light at a subwavelength scale. Optical metasurfaces have revolutionized design concepts in photonics, providing a new platform to develop ultrathin optical devices for the realization of OVs at subwavelength resolution. In this article, we will review the recent progress in optical metasurface-based OVs. We provide a comprehensive discussion on the optical manipulation of OVs, including OAM superposition, OAM sorting, OAM multiplexing, OAM holography, and nonlinear metasurfaces for OAM generation and manipulation. The rapid development of metasurface for OVs generation and manipulation will play an important role in many relevant research fields. We expect that metasurface will fuel the continuous progress of wearable and portable consumer electronics and optics where low-cost and miniaturized OAM related systems are in high demand.

A Regulated Pulse Current Driver with Spread Spectrum Clock Generator

This paper presents a regulated pulse current driver with a spread spectrum clock generator (SSCG) to lower the electromagnetic interference (EMI) effect. An SSCG is used and implemented by applying a triangular wave to modulate a voltage-controlled oscillator (VCO). The results show a 7 dBm reduction in the peak power level with a frequency deviation of 10%, demonstrating that the dominate harmonic is spread and distributed to adjacent frequencies, and the magnitude of harmonics is significantly reduced. The results demonstrate that the driver with a spread spectrum clock generator would help to reduce interference in sensitive electronic components and be suitable for portable consumer electronics applications.

Bio-Inspired Quinone Macromolecules Grafted on O, N, S, P Codoped Carbon Paper for High Energy Density Electrochemical

Growing environmental concerns have spurred investments in intermittent renewable energies and electric vehicles. The parallel boom in portable consumer electronics has placed considerable stress on electrochemical energy storage, creating environmental and availability issues for key inorganic materials. The need to switch to bio-sourced, widely available, organic materials is confronted by the low conductivity and stability of most candidates and the difficulties of creating an efficient, metal-free current collector. In this work, we present an acidic thermal oxidative treatment utilizing carbon paper as an efficient electrode for biosourced organic molecules. Following deposition of bio-sourced materials sepia melanin and catechin (a tannin) with high specific capacitance and energy density showed very promising results for supercapacitors. Up to 228 F/g capacitance, with 100% retention after 5 000 cycles, 100% coulombic efficiency, 69.71, 81.25 W h/kg and 22.20 and 12.66 kW/kg energy and power densities for sepia melanin and catechin, respectively, were achieved for symmetric supercapacitor devices.

Electrically Tunable Lenses: A Review.

Optical lenses with electrically controllable focal length are of growing interest, in order to reduce the complexity, size, weight, response time and power consumption of conventional focusing/zooming systems, based on glass lenses displaced by motors. They might become especially relevant for diverse robotic and machine vision-based devices, including cameras not only for portable consumer electronics (e.g. smart phones) and advanced optical instrumentation (e.g. microscopes, endoscopes, etc.), but also for emerging applications like small/micro-payload drones and wearable virtual/augmented-reality systems. This paper reviews the most widely studied strategies to obtain such varifocal “smart lenses”, which can electrically be tuned, either directly or via electro-mechanical or electro-thermal coupling. Only technologies that ensure controllable focusing of multi-chromatic light, with spatial continuity (i.e. continuous tunability) in wavefronts and focal lengths, as required for visible-range imaging, are considered. Both encapsulated fluid-based lenses and fully elastomeric lenses are reviewed, ranging from proof-of-concept prototypes to commercially available products. They are classified according to the focus-changing principles of operation, and they are described and compared in terms of advantages and drawbacks. This systematic overview should help to stimulate further developments in the field.

A Novel Optimal Charging Algorithm for Lithium-Ion Batteries Based on Model Predictive Control

Lithium-ion (Li-ion) batteries play a substantial role in portable consumer electronics, electric vehicles and large power energy storage systems. For Li-ion batteries, developing an optimal charging algorithm that simultaneously takes rises in charging time and charging temperature into account is essential. In this paper, a model predictive control-based charging algorithm is proposed. This study uses the Thevenin equivalent circuit battery and transforms it into the state-space equation to develop the model predictive controller. The usage of such models in the battery optimal control context has an edge due to its low computational cost, enabling the realization of the proposed technique using a low-cost Digital Signal Processor (DSP). Compared with the widely employed constant current-constant voltage charging method, the proposed charging technique can improve the charging time and the average temperature by 3.25% and 0.76%, respectively.

The design of an efficient class E-LCCL capacitive power transfer system through frequency tuning method

In this work, the optimum zero voltage switching (ZVS) of Class E-LCCL capacitive power transfer (CPT) was determined via frequency tuning method. Through this an efficient system can be guanranteed although there is a change in the capacitive plates distance. This study used a Class-E LCCL inverter, as it can operate at a high alternate current frequency, besides producing low switching losses and minimal power losses. Specifically, this study conducted simulations and experiments to analyse the performance of an LCCL CPT System at 1 MHz operating frequency and 24 V DC supply voltage. Using an air gap distance of 0.1 cm, the designed CPT system prototype successfully achieved an output power of 10W and an efficiency of 95.45%. This study also found that by tuning the resonant frequency of the Class E-LCCL system, the optimum ZVS can be obtained although capacitive plate distance was varied from 1-3 cm via experimental. The results of this study could benefit medical implant and portable device development, consumer electronics, and environments that involve electrical hazards.

Cyclic Phosphate-Based Nonflammable Electrolytes for High Energy and Safe Lithium-Ion Batteries

With the rapid development of renewable energy technologies, electric vehicles, and portable and wearable electronics, high-performance energy-storage devices are in ever-increasing demand. Among the various commercial energy-storage technologies, lithium-ion batteries have dominated the market in portable consumer electronics due to their high operating voltages and energy densities that can be attributed to their use of organic electrolytes.However, for the commercialization of large-scale applications, such as electric vehicles, further improvements in the energy and power densities must be achieved without sacrificing safety. The majority of current safety issues associated with Li-ion batteries arise from the utilization of highly volatile and flammable organic carbonates as solvents and the chemically unstable lithium hexafluorophosphate (LiPF6) as the salt in commercial electrolytes. Safety is becoming the hottest topic in the area of Li-ion batteries (LIBs). Although various safety measures have been applied, accidental fires still happen frequently due to the use of highly flammable organic electrolytes. As such, a solution to this issue is the use of a non-flammable organic solvent; however, no such solvent has been reported that is also suitable for use in LIBs.Herein, we, a joint team of battery researchers and organic chemists, designed and synthesized a new non-flammable fluorinated cyclic phosphate solvent (Figure 1) [1], namely, 2-(2,2,2-trifluoroethoxy)-1,3,2-dioxaphospholane 2-oxide (TFEP), for use in LIBs. As a rationale, we fused the chemical structural features of a conventional battery solvent (i.e., the ability to form an electrode-protective layer via ring-opening polymerization) and a fire retardant (i.e., the ability to trap H· radicals, which support combustion). An ethylene carbonate-free, LiPF6-free non-flammable electrolyte was prepared by dissolving 0.95 M LiN(SO2F)2 (LiFSA) in TFEP/2,2,2-trifluoroethyl methyl carbonate (FEMC, 1:3 v/v). Due to its ability to form a stable SEI, highly reversible and stable cycling was achieved for the graphite anode in such a non-flammable electrolyte without the use of high salt concentrations or SEI-forming additives. Moreover, the TFEP solvent enabled the stable cycling of high-voltage LiNi0.5Mn1.5O4 (LNMO) and high-capacity LiNi1/3Mn1/3Co1/3O2 (NMC) cathodes even in a dilute lithium bis(fluorosulfonyl)imide (LiFSI) electrolyte. This was attributed to its unique functions of forming an F-rich passivation layer that can prevent corrosion of the Al current collector and forming a polymeric cathode electrolyte interphase layer to prevent electrolyte oxidation and transition metal dissolution.Furthermore, silicon-based materials are promising anodes for next-generation Lithium-ion batteries because of their specific capacities, but they practical applications have been hindered by huge volume change, limited cycle life, and safety concerns. We found that cyclic phosphate-based electrolytes could also significantly improve the long-term cycling stability of SiO anode owing to the formation of a highly elastic inorganic-organic bilayer interphase. A LiNi0.6Mn0.2Co0.2|SiO cell with a high cutoff voltage of 4.4V shows 70.0 % capacity retention after 300 cycles with an average Coulombic efficiency of 99.9%.Further optimization of the unique chemical structure of this electrolyte would be expected to lead to the development of high-energy-density, sustainable, and safe Li-ion batteries. This work addresses the trade-off between battery voltage and safety, enhancing both factors simultaneously, which opens new frontiers in electrolyte developments toward safe LIBs with higher energy densities. Reference: [1]. Zheng Q, Yamada Y, Shang R, Ko S, Lee Y-Y, Kim K, Nakamura E, Yamada A. A cyclic phosphate-based battery electrolyte for high voltage and safe operation. Nat. Energy 2020, 5(4): 291-298. Figure 1

Manganese-Based Lithium-Ion Battery: Mn3O4 Anode Versus LiNi0.5Mn1.5O4 Cathode

Lithium-ion batteries (LIBs) are widely used in portable consumer electronics, clean energy storage, and electric vehicle applications. However, challenges exist for LIBs, including high costs, safety issues, limited Li resources, and manufacturing-related pollution. In this paper, a novel manganese-based lithium-ion battery with a LiNi0.5Mn1.5O4‖Mn3O4 structure is reported that is mainly composed of environmental friendly manganese compounds, where Mn3O4 and LiNi0.5Mn1.5O4 (LNMO) are adopted as the anode and cathode materials, respectively. The proposed structure improves battery safety and reduce costs compared with current battery technology, provides comparable energy density with that of traditional graphite-based batteries. First, the characteristics and the electrochemical performances of the Mn3O4 anode and the LNMO cathode are investigated separately against Li metal in half cell configurations, with promising performances being demonstrated by both electrodes. Then, a full cell structure with Mn3O4 against LNMO is constructed that provides an average discharge voltage of 3.5 V and an initial specific capacity of 86.2 mA·h·g−1. More importantly, the electrochemical performance of the LNMO‖Mn3O4 full cell and its possible decay mechanisms are discussed systemically; and efficient strategies are proposed to further improve both the electrochemical performance of Mn3O4 and the stability of LNMO.

Fast Operando GCMS Gas Analysis for Monitoring Electrolyte Decomposition in Lithium Ion Batteries

Lithium Ion Batteries (LIB) find not only wide use in portable devices and consumer electronics, but also attract increasing attention in stationary energy storage and the automotive sector. In this regard, LIBs play a significant role as intermediate energy storage due to their high volumetric and gravimetric energy, high power density, and long cycle life.To achieve the required performance, the interaction of novel anode and cathode materials is of paramount interest. Particularly, the safety of cell operation must be assessed with respect to the formation of volatile and reactive species during cycling which can negatively alter cell components. Gas chromatography mass spectroscopy (GCMS) has proven to be a reliable tool for species detection. Unfortunately, conventional GC systems lack time resolution for in-situ gas analysis regarding fast processes, for example battery failure. Therefore, developing operando testing methods with improved time resolution is key to giving insight into electrolyte alterations during battery operation.Here one of them, a novel multiplex injection method is presented as a monitoring technique for gas species arising from the decomposition of conventional LIB electrolytes. The combination of the multiplexing technique and GCMS allows the analysis of fast decomposition processes by 15 fold increase of time resolution compared to conventional gas chromatography. In addition, FTIR allows online monitoring of selected vibration bands. Commercially produced pouch cells were monitored with respect to evolving gas species during battery operation under overcharge conditions. For the decomposition of LiPF6 / organic carbonate- based electrolytes alkanes, alcohols, ethers, esters, aldehydes and also derivatives that appear in the presence of hydrofluoric acid such as fluorinated alkane species, have been evaluated.The author gratefully acknowledges the FFG (Austrian Research Promotion Agency) for funding this research within project No. 858298.