Coin Cell Battery Research Articles

Electrochemical synthesis of 1D core-shell Si/TiO2 nanotubes for lithium ion batteries

Silicon negative electrode for lithium ion battery was designed in the form of self-organized 1D core-shell nanotubes to overcome shortcomings linked to silicon volume expansion upon lithiation/delithiation typically occurring with Si nanoparticles. The negative electrode was formed on TiO2 nanotubes in two step electrochemical synthesis by means of anodizing of titanium and electrodeposition of silicon using ionic liquid electrolytes. Remarkably, it was found that the silicon grows perpendicularly to the z-axis of nanotube and therefore its thickness can be precisely controlled by the charge passed in the electrochemical protocol. Deposited silicon creates a continuous Si network on TiO2 nanotubes without grain boundaries and particle-particle interfaces, defining its electrochemical characteristics under battery testing. In the core-shell system the titania nanotube play a role of volume expansion stabilizer framework holding the nanostructured silicon upon lithiation/delithiation. The nature of Si shell and presence of titania core determine stable performance as negative electrode tested in half cell of CR2032 coin cell battery.

Coin-cell Supercapacitors Based on CVD Grown and Vertically Aligned Carbon Nanofibers (VACNFs)

Complete supercapacitors (SCs) comprising vertically aligned carbon nanofibers (VACNFs) as electrode materials have been assembled as coin-cells. The VACNFs were grown directly onto the current collector by direct current plasma enhanced chemical vapor deposition (DC-PECVD), thereby providing excellent contact with the current collector, but also eliminating the need of any binder. The vertical alignment facilitates fast ion transport and the electrolyte to access the entire surface of the CNFs. The morphology of the VACNFs was evaluated by scanning electron microscopy (SEM), while the performance was assessed by several methods: cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and device related cycling by galvanostatic charge/discharge. The capacitance, 3.64 mF/cm2 , is >15 times higher than the capacitance of a coin-cell without CNFs and the cyclic performance shows these proof-of-concept SCs to retain >80% of the capacitance after 2000 full charge/discharge cycles. The direct growth of VACNFs as electrodes at the current collector opens pathways for SC production using existing coin-cell battery production technology.

Characterizing Li-Ion Batteries Using in Situ MRI

We will describe our work on the development of techniques for assessing Li-ion batteries and battery materials via magnetic resonance imaging (MRI). The goal of these studies is to analyze battery degradation and energy storage mechanisms in situby imaging changes in both the electrolyte and the electrodes in a noninvasive fashion while a cell is charged or discharged. We will discuss recent breakthroughs we have made in performing MRI experiments on commercial pouch and coin cell batteries that allow diagnostic tests to be obtained without disassembling the cells. These tests can be run in situ or ex situ and can be used to indicate cycling properties of new battery components, to give a ‘fingerprint’ of manufactured cells for comparison and quality control purposes, or to offer engineering insights into the physical properties of the battery. We will also report on specific applications of MRI in functioning lithium metal batteries [1], where the technique can be used to correlate the behavior of the electrolyte concentration gradient to the type and rate of dendrite growth on the surface of the Li metal electrode. These studies have confirmed the existence of separate growth mechanisms in different charging regimes. The methodology is extremely sensitive to Li dendrite formation, opening the possibility of testing a broad range of materials and operating conditions to understand when dendrites grow and how they can be prevented. By developing a detailed understanding of the impact lithium dendrites have on their surroundings, we have been able to design fast 1H MRI experiments that are extremely sensitive to local dendrite growth [2]. The experiments allow for the 3D structure of the dendrites to be reconstructed, and are fast enough to capture the dendrite growth in real time, shedding light on the growth behavior, rate and morphology of the structures formed. Moreover, through simulations and a detailed analysis of the results obtained, we show how the MRI can be used to quantify the volume of dendrites grown. 1. Chang, H. J.; Ilott, A. J.; Trease, N. M.; Mohammadi, M.; Jerschow, A.; Grey, C. P. J. Am. Chem. Soc. 2015, 137(48), 15209–15216. 2. Ilott, A. J.; Mohammadi, M.; Chang, H. J.; Grey, C. P.; Jerschow; Proc. Natl. Acad. Sci. 2016 113 (39), 10779–10784. Figure caption: Regions of microscopic lithium dendrites that have grown between two lithium metal electrodes. The image is reconstructed from a 15 minute 1H MRI scan. Figure 1

Study to Improve Electrolytes in Sodium Batteries

With increasing need for batteries and energy storage, sodium batteries are of increasing demand. Lithium batteries are very popular but focus is being placed on sodium due to its higher abundance and subsequently, its lower cost. The human body also has a higher threshold for ingesting sodium than lithium as a nutrient, making it more biocompatible in ingestible battery1. The main focus of the study is to improve the electrolyte2,3. We test the electrolyte in a coin cell battery with sodium metal as the anode and the cathode. A variety of solvents, electrolytes, and additives are tested to optimize the electrolyte. Several different solvents were tested: ethylene carbonate (EC), propylene carbonate (PC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dimethoxyethane (DME), and dioxolane. These solvents were tested in different combinations with three electrolytes: sodium perchlorate (NaClO4), sodium bis(trifluoromethanesulfonyl)imide (NaTFSI), and sodium hexafluorophosphate (NaPF6). Lastly additives were tested in combination with above cases to test how they improve the electrolyte. The ionic liquid, 1-Butyl-1-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide (Pyr14TFSI) and lithium nitrate (LiNO3) were tested as additives. We look at the overpotential to gauge the effectiveness of the electrolytes by cycling symmetrical Na/Na cells. An example of the cycling with EC/PC/DEC and NaClO4 electrolyte is shown in the below Figure 1.

Free-Standing, Binder-Free Titanium Suboxide Nanofiber Based Sulfur Cathodes for Li-S Batteries

Lithium sulfur batteries, with a high theoretical specific energy of ~2680 Wh/kg, have attracted great attention in the recent years owing to the direct use of sulfur as a cathode, which is cost-effective, environmentally friendly and naturally abundant. However, shuttling of intermediate polysulfides between cathode and anode is one of the major practical limitations for the realization of Li-S batteries. Others include large volume expansion during lithium insertion, low sulfur utilization, and insulating nature of sulfur and lithium disulfide. Over the years, various carbon and inorganic materials (metal oxides, metal-organic frameworks) have been employed as hosts or polysulfide reservoirs to minimize the shuttling effect and improve the conductivity of cathodes in Li-S batteries. Recently, titanium suboxides (TinO2n-1; n>1), with two Ti3+ and (n-2)Ti4+ (3d0) ions, have been utilized as bifunctional sulphur hosts that not only provide good electrical conductivity, but also chemically bind with the intermediate lithium polysulfide preventing their escape. However, formation of titanium suboxides generally requires high temperature processing, which results in highly dense low surface area material reducing the potential polysulfide-host interaction surface. Here, we report the use of free-standing, binder-free titanium suboxide nanofibers as host material in sulfur cathodes. Titanium suboxide nanofibers are produced by electrospinning titanium isopropoxide solution in presence of polyvinylpyrrolidone and subsequently, heating at 850˚C to create oxygen vacancies through carbothermal reaction. Sulfur impregnation was carried out by rapid melt-diffusion technique to form final sulfur/titanium suboxide cathodes. Lithium-sulfur coin cell batteries were assembled using as-prepared free-standing cathodes (without any current collector and binder) with ~50 wt% sulfur loading (~1.5 mg cm-2) and cycled at C/5 rate (1C = 1675 mAh g-1) after conditioning at C/10 rate. The initial discharge capacity was ~976 mAh g-1 at C/5 rate, which stabilized to an average capacity of ~738 mAh g-1 after three cycles with coulombic efficiency >97%. The conducting titanium suboxide nanofibers allow the effective utilization of sulfur/Li2S during discharging/charging of cells and help to maintain high discharge capacity (~700 mAh g-1) over 100 cycles. The chemical interaction between these inorganic hosts and lithium polysulfide is under investigation and will be discussed in detail. The electrochemical results presented here show the potential of titanium suboxide family (different n values) as foreseeable solution to the shuttling effect for developing high performance Li-S batteries. Figure 1

Environmental-Friendly LiCoO2 Recycling from Libs Under the Assistance of Ultrasonic and Supercritical CO2

The rising demand for lithium calls for fully processing and using of all viable resources. Different processes in vogue aiming at recycling spent LIBs can be mainly divided into pyro/hydrometallurgical technologies. Pyro-processes burn off the organic toxic and flammable electrolytes and binder, while Hydro-processes may produce amounts of wastewater which contains complex chemical substances for further treatment. Herein, we aim at recovery the LiCoO2 from LIBs directly without bringing secondary pollutant. The cathode was shredded ( ~1.5 cm2 size) to separate active metal materials from aluminum foil in NMP (N-methyl-2-pyrrolidone) at room temperature under the ultrasonic assistance for 30 mins. The electrolyte and binder were dissolved in NMP, and later were recovered by Supercritical CO2 .NMP was reused and eventually recycled back by evaporation. The active materials was dried in vacuum for 12 hours at 100 ℃. XRD and SEM analysis indicated that the recycling material was LiCoO2 with high purity, and the electrochemical properties were tested by assembling coin cell batteries. The initial specific discharge capacity was more than 150mAh/g. GC-FID was investigated to reflect the unchanging composition of NMP. Our research fully care about environmental benign and economic feasibility.This technological process realizes the recycling of flammable liquid electrolyte and cathode materals and avoides the environmental harzards. Figure 1

Analysis and Tools for Improved Management of Connectionless and Connection-Oriented BLE Devices Coexistence.

With the introduction of low-power wireless technologies, like Bluetooth Low Energy (BLE), new applications are approaching the home automation, healthcare, fitness, automotive and consumer electronics markets. BLE devices are designed to maximize the battery life, i.e., to run for long time on a single coin-cell battery. In typical application scenarios of home automation and Ambient Assisted Living (AAL), the sensors that monitor relatively unpredictable and rare events should coexist with other sensors that continuously communicate health or environmental parameter measurements. The former usually work in connectionless mode, acting as advertisers, while the latter need a persistent connection, acting as slave nodes. The coexistence of connectionless and connection-oriented networks, that share the same central node, can be required to reduce the number of handling devices, thus keeping the network complexity low and limiting the packet’s traffic congestion. In this paper, the medium access management, operated by the central node, has been modeled, focusing on the scheduling procedure in both connectionless and connection-oriented communication. The models have been merged to provide a tool supporting the configuration design of BLE devices, during the network design phase that precedes the real implementation. The results highlight the suitability of the proposed tool: the ability to set the device parameters to allow us to keep a practical discovery latency for event-driven sensors and avoid undesired overlaps between scheduled scanning and connection phases due to bad management performed by the central node.

블루투스 스마트 기반의 내비게이팅 시스템

블루투스 스마트로 알려진 Bluetooth Low Energy(BLE)는 초저전력으로 동작하도록 설계되어 BLE 기반 디바이스들은 그 구성에 따라 하나의 코인셀(coin cell)로 몇 년간 동작이 가능하다. 또한 BLE는 수신신호세기 정보를 기반으로 두 BLE 디바이스 사이의 근사적 거리를 추정 할 수 있다. 이러한 특징으로 인하여 실내 또는 실외의 근거리 영역에서 GPS보다 상대적으로 높은 정밀도의 내비게이션 서비스를 제공 할 수 있다. 본 논문에서는 BLE를 이용한 실제 내비게이션 테스트 베드를 구성하고 실외 근거리 영역에서의 동작을 검증한다. 검증 실험에서 BLE 기반의 비콘들은 고정된 위치에 설치되어 주기적으로 Universally Unique IDentifier(UUID) 전송하며, 사용자 스마트 디바이스는 이를 수신하여 거리값을 추출하고 UUID를 셀룰러 또는 와이파이 망을 통해 데이터베이스로 전송한다. 데이터베이스는 해당 UUID에 바인딩된(binding) 관련 정보를 사용자 디바이스에 피드백하고, 이를 수신한 사용자 디바이스는 추출된 거리값과 함께 주변 정보 및 지도상에서 사용자 위치를 더욱 정밀하게 표시하는 내비게이션 서비스를 제공한다. 본 논문을 통하여 BLE 기반의 내비게이팅 응용이 실현 가능함을 확인할 수 있으며, 더 나아가 이러한 시스템이 실내 내비게이션으로도 충분히 구현될 수 있음을 확인 할 수 있다. Bluetooth Low Energy (BLE), also known as Bluetooth Smart, has ultra-low power consumption; in fact, BLE-enabled devices can run on a single coin cell battery for several years. In addition, BLE can estimate the approximate distance between two devices using the Received Signal Strength Indication (RSSI) feature, enabling relatively precise navigation in indoor and small outdoor areas where GPS is not an option. In this paper, an experimental setup is presented in which BLE is used for navigation within a small outdoor area. BLE-based beacons are installed in fixed positions, which periodically transmit a universally unique identifier (UUID). A smart device receives the UUID and sends it to a database server using cellular or Wi-Fi technology. The server returns fixed position information corresponding to the received UUID codes, and the smart device uses that information to compute its current position based on relative signal strengths, and display it on a map. These results demonstrate the successful application of BLE technology for navigation in small outdoor areas. This system can be implemented for indoor navigation as well.

Powering the next Billion devices with wi-fi

We present the first power over Wi-Fi system that delivers power to low-power sensors and devices and works with existing Wi-Fi chipsets. We show that a ubiquitous part of wireless communication infrastructure, the Wi-Fi router, can provide far field wireless power without significantly compromising the network's communication performance. Building on our design, we prototype battery-free temperature and camera sensors that we power with Wi-Fi at ranges of 20 and 17 ft, respectively. We also demonstrate the ability to wirelessly trickle-charge nickel--metal hydride and lithium-ion coin-cell batteries at distances of up to 28 ft. We deploy our system in six homes in a metropolitan area and show that it can successfully deliver power via Wi-Fi under real-world network conditions without significantly degrading network performance.

Opportunistic Sensor Data Collection with Bluetooth Low Energy.

Bluetooth Low Energy (BLE) has gained very high momentum, as witnessed by its widespread presence in smartphones, wearables and other consumer electronics devices. This fact can be leveraged to carry out opportunistic sensor data collection (OSDC) in scenarios where a sensor node cannot communicate with infrastructure nodes. In such cases, a mobile entity (e.g., a pedestrian or a vehicle) equipped with a BLE-enabled device can collect the data obtained by the sensor node when both are within direct communication range. In this paper, we characterize, both analytically and experimentally, the performance and trade-offs of BLE as a technology for OSDC, for the two main identified approaches, and considering the impact of its most crucial configuration parameters. Results show that a BLE sensor node running on a coin cell battery can achieve a lifetime beyond one year while transferring around 10 Mbit/day, in realistic OSDC scenarios.

IoT Based Low Cost Single Sensor Node Remote Health Monitoring System

In developing countries, population increase is not sufficiently matched by increase in available health care resources. Inspite of technology advances, proper medical facility and resources are still not available to a large percentage of population, especially those having low income and living in rural or remote areas. There is an urgent need for development of a low cost and highly reliable technology for monitoring healthcare for those living in such areas that provides rapid monitoring of basic vital health parameters for large numbers of people, and making this data readily available to doctor present anywhere in the world. A novel and an efficient biomedical device has been designed which can quickly monitor the vital signs of large number of people simultaneously and transmit that information wirelessly to the doctor or medical facility present anywhere in the world. The instrument is represented by a hub and spoke model with the spokes being the sensor nodes consisting of a microcontroller MSP430G2553 and a wireless transceiver nRF24L01 (IEEE 802.15.4). The hub consists of a Raspberry Pi 3 with the same transceiver. The data received at the hub can be transmitted to the doctor through the inbuilt IEEE 802.11 (Wi-Fi protocol) of Raspberry Pi 3. All that the instrument needs to work is a Wi-Fi or an Ethernet connection and all the sensor nodes can be powered from the coin cell batteries.

Validation of a Portable Low-Power Deep Brain Stimulation Device Through Anxiolytic Effects in a Laboratory Rat Model.

Deep brain stimulation (DBS) devices deliver electrical pulses to neural tissue through an electrode. To study the mechanisms and therapeutic benefits of deep brain stimulation, murine preclinical research is necessary. However, conducting naturalistic long-term, uninterrupted animal behavioral experiments can be difficult with bench-top systems. The reduction of size, weight, power consumption, and cost of DBS devices can assist the progress of this research in animal studies. A low power, low weight, miniature DBS device is presented in this paper. This device consists of electronic hardware and software components including a low-power microcontroller, an adjustable current source, an n-channel metal-oxide-semiconductor field-effect transistor, a coin-cell battery, electrode wires and a software program to operate the device. Evaluation of the performance of the device in terms of battery lifetime and device functionality through bench and in vivo tests was conducted. The bench test revealed that this device can deliver continuous stimulation current pulses of strength [Formula: see text], width [Formula: see text], and frequency 130 Hz for over 22 days. The in vivo tests demonstrated that chronic stimulation of the nucleus accumbens (NAc) with this device significantly increased psychomotor activity, together with a dramatic reduction in anxiety-like behavior in the elevated zero-maze test.

Polymerized ionic liquid diblock copolymer as solid-state electrolyte and separator in lithium-ion battery

A polymerized ionic liquid diblock copolymer (PILBCP-TFSI), poly(MMA-b-MUBIm-TFSI), consisting of an ionic liquid monomer, (1-[(2-methacryloyloxy)undecyl]-3-butylimidazolium bis(trifluoromethane)sulfonamide) (MUBIm-TFSI), and a non-ionic monomer, methyl methacrylate (MMA), was synthesized via reverse addition fragmentation chain transfer polymerization followed by anion exchange metathesis. Free standing, mechanically stable transparent solid polymer films were produced with PILBCP-TFSI containing 1 M lithium bis(trifluoromethane)sulfonamide in 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (Li-TFSI/EMIm-TFSI). The resulting PILBCP-TFSI + Li-TFSI/EMIm-TFSI films possessed ion conductivities from 1 to 10 mS cm−1 from 25 °C to 105 °C. Solid-state lithium-ion coin cell batteries were assembled and tested at room temperature with PILBCP-TFSI + Li-TFSI/EMIm-TFSI films as the solid-state electrolyte and separator and resulted in a maximum discharge capacity of 112 mAh g−1 at 0.1 C with a Coulombic efficiency greater than 94% over 100 cycles. For the first time, these results demonstrate the feasibility of PIL block copolymers as solid-state electrolytes and separators in lithium-ion batteries.

Decoupling data-at-rest encryption and smartphone locking with wearable devices

Smartphones store sensitive and confidential data, e.g., business related documents or emails. If a smartphone is stolen, such data are at risk of disclosure. To mitigate this risk, modern smartphones allow users to enable data encryption, which uses a locking password to protect the data encryption key. Unfortunately, users either do not lock their devices at all, due to usability issues, or use weak and easy to guess 4-digit PINs. This makes the current approach of protecting confidential data-at-rest ineffective against password guessing attackers. To address this problem we design, implement and evaluate the Sidekick system — a system that uses a wearable device to decouple data encryption and smartphone locking. Evaluation of the Sidekick system revealed that the proposal can run on an 8-bit System-on-Chip, uses only 4 Kb/20 Kb of RAM/ROM, allows data encryption key fetching in less than two seconds, while lasting for more than a year on a single coin-cell battery.

Stabilizing the Solid Electrolyte Interphase on Silicon-Based Anode Materials for Lithium-Ion Batteries By in-Situ Reductive Electropolymerization

Increasing the capacity of Li-ion batteries and making the involved interfaces much more stable is one of the crucial current challenges for sustainable energy use.1 Silicon anodes promise almost a 10-fold capacity increase with respect to conventional graphite anodes.2 The continuous degradation of the Solid Electrolyte Interphase (SEI) at the surface of silicon-based anode materials has been recognized as the key problem of these electrodes, currently preventing their commercial introduction.3 The effect of the addition of additives to the electrolyte has been investigated in the past on graphite anodes, resulting in the use of FEC and VC in commercial lithium-ion batteries. However, due to the severe volume expansion of silicon during battery cycling, the SEI is under much higher stresses compared to graphite. Hence the stabilization of the SEI on silicon is required to improve its battery performance. Here we present a methodology to specifically introduce polymer species into the SEI. We analyzed the interfacial film using Hard X-ray Photoelectron Spectroscopy (HAXPES), Raman spectroscopy and electrochemical testing. HAXPES enabled us to address the full depth-dependent layer chemistry and allowed us to probe the interface of the solid-electrolyte interphase and the silicon-based electrode. Figure 1a shows the C1s spectrum of the SEI on a silicon based anode after cycling using a standard electrolyte and for Figure 1b an electrolyte with the monomer additive. A detailed analysis gives information on the SEI layer thickness and the distribution of the additive-based polymer formation. In particular Br2p3/2 HAXPES spectra reveal more details on the mechanism. The battery performance of the additives was investigated by coin-cell battery testing and provides a more detailed view into the influence of electrolyte additives on the SEI. REFERENCES 1. J. B. Goodenough and K.-S. Park, J. Am. Chem. Soc. 135, 1167-1176 (2013). 2. M. N. Obravac and L. Christensen, Electrochemical and Solid-State Letters 7, A93-A96 (2004). 3. B. Philippe, K. Edström et al., Chemistry of Materials 24, 1107-1115 (2012). Figure 1

Influence of Porous Separators on the Ionic Conductivity of Nonflammable Liquid Perfluoropolyether Electrolytes

Conventional Lithium-ion coin cell batteries contain a volatile flammable liquid electrolyte, impregnated in a porous separator. This leads to a serious safety issue with, for example, the possibility of flammable reaction products and internal short-circuits.[1] Commercial microporous polyolefin membranes, made of semi-crystalline polymers as polyethylene (PE) and polypropylene (PP), have been widely used as battery separators. [2] The main functions of the separator are to act as a physical barrier to prevent short-cut between the two electrodes and to allow ionic transport. Ionic transport within the separator depends on several factors such as the separator geometry, porosity and tortuosity, the electrolyte resistance and wettability.[3] Thus, the presence of the separator leads to an effective ionic conductivity lower than the bulk electrolyte conductivity, and an increase of the Li battery internal resistance. The recent development of non-flammable liquid electrolytes based on functionalized perfluoropolyethers (PFPEs) opened the path of safe Li-ion batteries.[4, 5] PFPE is chemically resistant, non-crystalline, and nonflammable exhibit low glass transition temperature and low toxicity. It was demonstrated that a methyl carbonate-terminated perfluoropolyether (see Figure 1) is suitable for lithium battery operation, but optimization is necessary to improve the performance. So far little is known on the transport properties of this new class of non-flammable liquid electrolytes within the separator. As for any conventional liquid electrolyte, investigating the nature of the separator and its effect on the effective ionic conductivity is required to achieve an optimal battery design. We investigated the physico-chemical and electrochemical properties of three commercial separators: a PP monolayer, a trilayer PP-PE-PP and a polytetrafluoroethylene (PTFE). The ionic conductivities of low molecular weight PFPEs, with dimethyl carbonate or ethoxylated alcohol end-groups, doped with the lithium salt LiTFSI was measured as a function of the temperature either in the bulk or in the presence of the separators. For comparison, a conventional liquid electrolyte made of 1M LiPF6 in a mixture of ethylene carbonate and dimethyl carbonate was also studied. In addition, the effective ionic conductivity of each electrolyte impregnated in the separator is modeled based on the bulk electrolyte conductivity and a separator morphological form factor.

Enhanced optical discrimination system based on switchable retroreflective films

Reported herein is the design, characterization, and demonstration of a laser interrogation and response optical discrimination system based on large-area corner-cube retroreflective films. The switchable retroreflective films use light-scattering liquid crystal to modulate retroreflected intensity. The system can operate with multiple wavelengths (visible to infrared) and includes variable divergence optics for irradiance adjustments and ease of system alignment. The electronic receiver and switchable retroreflector offer low-power operation (<4 mW standby) on coin cell batteries with rapid interrogation to retroreflected signal reception response times (<15 ms). The entire switchable retroreflector film is <1 mm thick and is flexible for optimal placement and increased angular response. The system was demonstrated in high ambient lighting conditions (daylight, 18k lux) with a visible 10-mW output 635-nm source out to a distance of 400 m (naked eye detection). Nighttime demonstrations were performed using a 1.5-mW, 850-nm infrared laser diode out to a distance of 400 m using a night vision camera. This system could have tagging and conspicuity applications in commercial or military settings.

Real-time monitoring of internal temperature evolution of the lithium-ion coin cell battery during the charge and discharge process

The internal temperature is the most effective parameter to determine whether the battery is entering the danger zone. However, it is also the most difficult to be monitored in real time. This paper focuses on the real-time monitor of internal temperature evolution of the lithium-ion coin cell battery during charge and discharge. First, the experimental set-up is introduced, which consists of four parts: the embedded sensor, incubator, data transmission and collection. This shows that the internal temperatures rise rapidly at the end of the discharge process while the difference between internal temperature and surface temperature is insignificant during the 0.5 C rate charge process. With the increasing C-rate, the heat generation rate increases correspondingly. Secondly, the influence of the embedded sensor on electrochemical performance is evaluated at different C-rates. It is found that the capacity difference is about 8.28% for the 0.1 C-rate charge process between the cases with and without the embedded sensor. With the increase of the charge rate, the capacity difference becomes larger and even approached 50% under 2 C-rate. Finally, a novel thermal model is developed to determine the heat transfer parameters for the coin cell based on the monitoring data. The heat flow during 1 C and 2 C discharge tests is calculated by the thermal model and temperature curves, which has the same tendency with the experimental results using the micro-calorimeter technique.

A novel high-throughput setup forin situpowder diffraction on coin cell batteries

A new setup forin situexperiments with up to eight electrochemical cells, especially battery coin cells, and the corresponding custom-madein situcells are presented. The setup is primarily optimized for synchrotron powder diffraction measurements. As a newly constructed experimental setup, thein situcoin cell holder was tested for positional errors of the cells and the reliability of the diffraction as well as electrochemical measurements. The overall performance characteristics of the sample holder are illustrated by measurements on LiMn2O4and LiNi0.35Fe0.3Mn1.35O4spinel-based positive electrode materials.

Analysis of electrolyte level change in a lithium air battery

A two-dimensional physical model that employs the deformed mesh method to track the electrolyte level in a Li-air coin cell battery is presented and used to investigate the effects of electrolyte level drop during cell discharge. The electrolyte level drop is caused by solid phase volume decrease and electrolyte solvent evaporation. Simulation results show that by neglecting the drop in electrolyte level, a Li-air battery model would under-estimate cell discharge capacity by as much as 22.5% in the parameter range studied. This counter-intuitive result is explained by an in-depth analysis of simulation results. A more realistic prediction of Li2O2 deposit distribution is obtained, with the peak value of Li2O2 volume fraction in the middle of the cathode instead of on the top surface, as predicted by previous studies. The interaction between the battery and its surroundings is considered by incorporating the air chamber into the computation domain. The diffusion of solvent vapor and oxygen in this chamber is included. For batteries using volatile solvents such as DMF, increasing the air chamber radius from 5 cm to 15 cm would result in a 72% increase of discharge capacity at the cost of losing a large amount of electrolyte.