Lithium-ion Battery Thermal Safety by Early Internal Detection, Prediction and Prevention

Advancements in Battery Monitoring: Harnessing Fiber Grating Sensors for Enhanced Performance and Reliability

Batteries play a crucial role as energy storage devices across various industries. However, achieving high performance often comes at the cost of safety. Continuous monitoring is essential to ensure the safety and reliability of batteries. This paper investigates the advancements in battery monitoring technology, focusing on fiber Bragg gratings (FBGs). By examining the factors contributing to battery degradation and the principles of FBGs, this study discusses key aspects of FBG sensing, including mounting locations, monitoring targets, and their correlation with optical signals. While current FBG battery sensing can achieve high measurement accuracies for temperature (0.1 °C), strain (0.1 με), pressure (0.14 bar), and refractive index (6 × 10-5 RIU), with corresponding sensitivities of 40 pm/°C, 2.2 pm/με, -0.3 pm/bar, and -18 nm/RIU, respectively, accurately assessing battery health in real time remains a challenge. Traditional methods struggle to provide real-time and precise evaluations by analyzing the microstructure of battery materials or physical phenomena during chemical reactions. Therefore, by summarizing the current state of FBG battery sensing research, it is evident that monitoring battery material properties (e.g., refractive index and gas properties) through FBGs offers a promising solution for real-time and accurate battery health assessment. This paper also delves into the obstacles of battery monitoring, such as standardizing the FBG encapsulation process, decoupling multiple parameters, and controlling costs. Ultimately, the paper highlights the potential of FBG monitoring technology in driving advancements in battery development.

Direct measurement of internal temperatures of commercially-available 18650 lithium-ion batteries

Direct access to internal temperature readings in lithium-ion batteries provides the opportunity to infer physical information to study the effects of increased heating, degradation, and thermal runaway. In this context, a method to insert temperature sensors into commercial 18650 cells to determine the short- and long-term effects through characterization testing is developed. Results show that sensor insertion only causes a decrease in capacity of 0.5-2.3%, and an increase in DC resistance of approximately 15 mΩ. The temperatures of the modified cells are approximately 0.5 °C higher than the control cells, the difference between the internal and external temperature readings of the modified cells is approximately 0.4 °C, and the modified cells exhibit the same temperature behavior and trend during cycling as the control cells. The cells are able to operate and collect data for 100-150 cycles before their capacities fade and resistances increase beyond what is observed in the control cells. The results of the testing show that cells modified with internal temperature sensors provide useful internal temperature data for cells that have experienced little or no cyclic aging.

Pathways to Next-Generation Fire-Safe Alkali-Ion Batteries

High energy and power density alkali-ion (i.e., Li+ , Na+ , and K+ ) batteries (AIBs), especially lithium-ion batteries (LIBs), are being ubiquitously used for both large- and small-scale energy storage, and powering electric vehicles and electronics. However, the increasing LIB-triggered fires due to thermal runaways have continued to cause significant injuries and casualties as well as enormous economic losses. For this reason, to date, great efforts have been made to create reliable fire-safe AIBs through advanced materials design, thermal management, and fire safety characterization. In this review, the recent progress is highlighted in the battery design for better thermal stability and electrochemical performance, and state-of-the-art fire safety evaluation methods. The key challenges are also presented associated with the existing materials design, thermal management, and fire safety evaluation of AIBs. Future research opportunities are also proposed for the creation of next-generation fire-safe batteries to ensure their reliability in practical applications.

Hybrid nanomaterial inks for printed resistive temperature sensors with tunable properties to maximize sensitivity

Nanomaterial-based inks are one of the essential building blocks for printed electronics. Inks consisting of silver nanoparticles have been well received as conductive inks for printed electronics among researchers and industry due to their good electrical performance, relatively low sintering temperature, and wide range of commercial availability. However, homogenous silver nanoparticle inks can lack the appropriate attributes required for robust printed physical sensors. In this work, we demonstrate that fully printed resistive temperature detector (RTD) sensors can benefit from ink hybridization. Specifically, we investigate RTDs printed by aerosol jet printing of hybrid nickel-copper-silver nanoparticle inks. We show that the overall sensitivity of the printed sensors can be enhanced through the introduction of these varied particles due to intentionally incorporated interfacial obstacles within the percolation network. While the temperature coefficient of resistance is decreased, the change in resistance per change in temperature can be maximized through the enhanced scattering provided by nickel and copper particle constituents. We report a sensitivity increase of 300% through utilizing 40% (by volume) mixture of silver and copper/nickel xylene-based inks. The results are corroborated through SEM/EDS analysis to understand the final weight percent of varied elements within the printed thin film. This magnitude of sensitivity opens up the possibility of utilizing printed RTDs for a wider range of sensing applications, where probing electronics are often low-cost.

Mapping and Modeling Physicochemical Fields in Solid-State Batteries

The safety and energy density of solid-state batteries can be, in principle, substantially increased compared with that of conventional lithium-ion batteries. However, the use of solid-state electrolytes instead of liquid electrolytes introduces pronounced complexities to the solid-state system because of the strong coupling between different physicochemical fields. Understanding the evolution of these fields is critical to unlocking the potential of solid-state batteries. This necessitates the development of experimental and theoretical methods to track electrochemical, stress, crack, and thermal fields upon battery cycling. In this Perspective, we survey existing characterization techniques and the current understanding of multiphysics coupling in solid-state batteries. We propose that the development of experimental tools that can map multiple fields concurrently and systematic consideration of material plasticity in theoretical modeling are important for the advancement of this emerging battery technology. This Perspective provides introductory material on solid-state batteries to scientists from a broad physical chemistry community, motivating innovative and interdisciplinary studies in the future.

Impedimetric Chemosensing of Volatile Organic Compounds Released from Li-Ion Batteries

Detection of toxic and flammable gases and volatile organic compounds (VOCs) released from Li-ion batteries during thermal runaway can generate an early warning. A submicron (∼0.15 μm)-thick poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) sensor film is coated on a platinum electrode through a facile aqueous dispersion. The resulting sensor reliably detected different volatile organic compounds (VOCs) released during the early stages of thermal runaway of lithium-ion batteries (LIBs) even at low concentrations. The single-electrode sensor utilizes impedance spectroscopy to measure ethyl methyl carbonate and methyl formate concentrations at 5, 15, and 30 ppm independently and in various combinations using ethanol as a reference. In contrast to DC resistance measurement, which provides a single parameter, impedance spectroscopy provides a wealth of information, including impedance and phase angle at multiple frequencies as well as fitted charge transfer resistance and constant-phase elements. Different analytes influence the measurement of different parameters to varying degrees, enabling distinction using a single sensing material. The response time for ethyl methyl carbonate was measured to be 6 s. Three principal components (PCs) preserve more than 95% of information and efficiently enable discrimination of different classes of analytes. Application of low-power PEDOT:PSS-based gas sensors will facilitate cost-effective early detection of VOCs and provide early warning to battery management systems (BMS), potentially mitigating catastrophic thermal runaway events.