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An effective and compact thermal management system is essential for modern lithium-ion (Li-ion) battery powered vehicles, which involve rigorous constraints on weight and volume. In this paper, a phase change material (PCM) based battery internal cooling system is proposed by replacing the hollow mandrel in cylindrical battery with a PCM-filled mandrel, and it is tested on a fabricated steel cell. With verifying its effectiveness in cooling, as well as the accuracy of the thermal model, numerical studies are carried out on a Li-ion battery submodule consisting of 40 cylindrical batteries. Variables including PCM species ( n -octadecane, n -eicosane, and n -docosane), PCM core size, and PCM core size distribution are used in the simulations to optimize the design by examining the performance indices involving temperature, temperature difference, PCM solidification time, and pack compactness. The numerical results show that the PCM cores can effectively alleviate the temperature rise inside the battery pack, and a uniform temperature distribution can be obtained when thicker PCM cores are embedded in the interior batteries. A pack compactness study indicates that the internal cooling is a space-saving design that facilitates the achievement of the high energy density of the battery pack. [ABSTRACT FROM AUTHOR]

The safety of lithium-ion battery (LIB)-powered electric vehicles and stationary energy storage devices relies on a high-efficient state of health (SOH) prediction of the LIB system. In this regard, the health indicators (HIs) play a critical role in determining the SOH prediction performance. Due to the rich kinetic and dynamic information of LIB system measured by electrochemical impedance spectroscopy (EIS), valuable HIs can be extracted from EIS for SOH prediction based on machine learning. The present work is concentrated on how to extract and tune HIs for a high-efficient SOH prediction based on the Gaussian process regression (GPR) model. First, 6-dimension feature x DRT are extracted from 120-dimension impedance x EIS with distribution of relaxation times (DRT) for 4 battery samples; secondly, the extracted x DRT is tuned into x ARD by the GPR with automatic relevance determination (ARD) kernels; thirdly, the SOH prediction results show that the tuned x ARD needs less training time than the raw x EIS does for the ARD-GPR model. Furthermore, x ARD has stronger robustness than x EIS with respect to kernel functions, training sets, and samples. Summarily, the method addressed in the present work to extract HIs may offer a promising solution for battery SOH prediction with a stronger robustness and less training time. [Display omitted] • Extracted health indicators from EIS by DRT method for battery SOH prediction. • Tuned health indicators extracted from EIS by DRT based on ARD-GPR model. • Demonstrated robustness of the tuned health indicators for battery SOH prediction. [ABSTRACT FROM AUTHOR]

Li-ion batteries are the state-of-the-art power sources for portable electronics, electric vehicles, and aerospace applications. The safety issues regarding Li-ion batteries arouse particular attentions after several accidents reported in recent years. Among various abuse conditions, nail penetration is one of the most dangerous for Li-ion batteries due to the accumulated heat generation, which could give rise to the thermal runaway and could damage entire energy storage system. In this paper, an electrochemical-thermal coupling model is developed to study the nail penetration process of Li-ion batteries. By introducing joule heating at the nail location, the model shows good agreement with the testing results. With this verified model, a comprehensive parametric study is carried out to investigate the effects of battery capacity, internal resistance, and nail diameter on the electrochemical and thermal behaviors of Li-ion batteries during the penetration processes. Furthermore, three possible solutions to prevent the thermal runaway, which includes decreasing the state of charge, improving heat dissipation, and increasing contact resistance, are compared and discussed in detail based on a series of simulations. [ABSTRACT FROM AUTHOR]

Safety is the first priority in lithium ion (Li-ion) battery applications. A large portion of electrical and thermal hazards caused by Li-ion battery is associated with short circuit. In this paper, both external and internal short circuit tests are conducted. Li-ion batteries and battery packs of different capacities are used. The results indicate that external short circuit is worse for smaller size batteries due to their higher internal resistances, and this type of short can be well managed by assembling fuses. In internal short circuit tests, higher chance of failure is found on larger capacity batteries. A modified electrochemical–thermal model is proposed, which incorporates an additional heat source from nail site and proves to be successful in depicting temperature changes in batteries. Specifically, the model is able to estimate the occurrence and approximate start time of thermal runaway. Furthermore, the effectiveness of a hydrogel based thermal management system in suppressing thermal abuse and preventing thermal runaway propagation is verified through the external and internal short tests on batteries and battery packs. [ABSTRACT FROM AUTHOR]

Lithium ion (Li-ion) battery has emerged as an important power source for portable devices and electric vehicles due to its superiority over other energy storage technologies. A mild temperature variation as well as a proper operating temperature range are essential for a Li-ion battery to perform soundly and have a long service life. In this review paper, the heat generation and dissipation of Li-ion battery are firstly analyzed based on the energy conservation equations, followed by an examination of the hazardous effects of an above normal operating temperature. Then, advanced techniques in respect of electrode modification and systematic battery thermal management are inspected in detail as solutions in terms of reducing internal heat production and accelerating external heat dissipation, respectively. Specifically, variable parameters like electrode thickness and particle size of active material, along with optimization methods such as coating, doping, and adding conductive media are discussed in the electrode modification section, while the current development in air cooling, liquid cooling, heat pipe cooling, and phase change material cooling systems are reviewed in the thermal management part as different ways to improve the thermal performance of Li-ion batteries. [ABSTRACT FROM AUTHOR]

Lithium ion (Li-ion) battery, consisting of multiple electrochemical cells, is a complex system whose high electrochemical and thermal stability is often critical to the well-being and functional capabilities of electric devices. Considering any change in the specifications may significantly affect the overall performance and life of a battery, an investigation on the impacts of electrode thickness on the electrochemical and thermal properties of lithium-ion battery cells based on experiments and a coupling model composed of a 1D electrochemical model and a 3D thermal model is conducted in this work. In-depth analyses on the basis of the experimental and simulated results are carried out for one cell of different depths of discharge as well as for a set of cells with different electrode thicknesses. Pertinent results have demonstrated that the electrode thickness can significantly influence the battery from many key aspects such as energy density, temperature response, capacity fading rate, overall heat generation, distribution and proportion of heat sources. [ABSTRACT FROM AUTHOR]

Abstract: As a typical heat source in the operation of lithium-ion (Li-ion) battery, reversible heat (RH) makes a considerable contribution to the temperature variation of the battery, and the determination of this contribution is of great significance, especially for mission-critical applications. In previous research works, the determination of including or excluding the RH was typically made based on the rate of discharge. This study, however, finds that the importance of RH could be more meaningfully judged based on its contribution to the overall thermal response of Li-ion battery at various conditions. An improved electrochemical–thermal coupling model is developed to incorporate the RH. This model is applied to simulate the operation of batteries with different physical properties (e.g., electrode thickness and active material particle size) under different discharge rates. The simulation results are compared in terms of RH generation rates, battery temperature, as well as several other associated characteristics. It is found that the significance of RH to the overall heat generation varies when different intrinsic and extrinsic parameters are considered. This significance becomes more appreciable for batteries with thinner electrodes and/or finer active material particles. A correction diagram is then proposed to modify the results for thermal analyses without including RH. [Copyright &y& Elsevier]

Instable surface structure and low capacity retention hinder the further application of high voltage LiNi 0.5 Mn 1.5 O 4 (LNMO) cathode in lithium-ion battery. In order to promote its electrochemical performances, Li 6.4 La 3 Al 0.2 Zr 2 O 12 (LLAZO) with the intrinsic property of fast ion conductivity has been employed as a protective layer to modify surface of LNMO. By regulating the LLAZO contents, 1 wt % LLAZO coated LNMO (LLAZO-1) cathode shows a high capacity of 92.1 mAh g−1 over 600 cycles with a capacity retention of 72.6% at 1 C and a reversible capacity of 57.9 mAh g−1 at 20 C, much higher than those of pristine LNMO. Further investigation indicates that the greatly improved electrochemical performances of LLAZO-1 can be attributed to the LLAZO modification, which including the LLAZO surface coating and La3+ and Zr4+ gradient co-doping. In addition, the LLAZO precursor significantly restricts the growth of LNMO precursor particles during calcination process, shorting Li+ migration pathway. Thus, modification strategy effectively improves the structure stability of LNMO, accompanied with the enhancement in lithium-ion diffusion kinetics performances and confinement in particle growth. This optimization approach with tri-functions sheds light on novel electrode design and construction in rechargeable batteries. Image 1 • The novel strategy of modification for cathode precursor proposed in this work. • Restricting the particle growth of LNMO during the calcination process. • Gradient doping of La3+ and Zr4+ facilitate Li+ transportation at the interface. [ABSTRACT FROM AUTHOR]

Highlights • A method for thermal management of battery using phase change material is proposed. • Temperature of battery is rapidly decreased using flexible phase change material. • Flexible phase change material fills the gap due to low thermal contact resistance. • The usage time of the battery pack is effectively extended. • Simulation results show good agreement with experimental results. Abstract A method for thermal management of Li-ion battery pack with the application of various flexible form-stable composite phase change materials (CPCMs) is proposed, and investigated both numerically and experimentally. Flexible CPCMs embedded in battery pack lower the thermal contact resistance, thereby improving the thermal control performance. Experimental results show that with the application of flexible CPCMs, the battery temperature drops by 18 °C at 10 C discharge rate. In addition, flexible CPCM has better thermal control performance than the case of conventional CPCMs. This allows Li-ion battery pack to safely work for an extended period of time without exceeding upper temperature limits. The thermal control performance is observed to vary considerably with three factors: the phase change temperature of flexible CPCMs, working condition, and the ambient temperature. One flexible CPCM with phase change temperature of 33 °C is found to be optimal for small power levels and low ambient temperatures. Another flexible CPCM with 47 °C of phase change temperature is suitable for high power levels, short-term high heat fluxes, and high ambient temperatures. The numerical results are in reasonable accordance with experimental ones. [ABSTRACT FROM AUTHOR]

Abstract SnS-based materials show great potential as high-capacity anode candidates of Li-ion batteries owing to their dual-mechanisms of conversion and alloying reactions. However, the practical application is substantially hampered by its poor electrochemical utilization and stability. Herein, we demonstrate three-dimensional SnS/C microflowers prepared by a controllable self-polymerization and carbonization of polydopamine-coated SnS 2 precursors. The building nanosheet consists of uniform encapsulation of ultrafine SnS nanoparticles into the conductive carbon framework. Benefiting from the nanoscaled building blocks and the porous three-dimensional architecture, the carbon-encapsulated nano-SnS microflowers show a significant enhancement in the electrochemical reaction kinetics and durability. As a result, the hybrid exhibits a high specific capacity of ∼1000 mAh g−1 at 0.1 A g−1 with a high initial Coulombic efficiency of 84.2%, good rate capability, and stable cyclability. The present work provides a reliable strategy for the rational fabrication of carbon-encapsulated SnS composites for high-performance Li-ion batteries. Graphical abstract Image 1 Highlights • Three-dimensional microflowers assembled by SnS/C nanosheets are prepared. • SnS nanoparticles are uniformly encapsulated by carbon framework. • The SnS/S hybrid delivers a high specific capacity of ∼1000 mAh g−1. • The SnS/S hybrid exhibits excellent rate/cycling performance. [ABSTRACT FROM AUTHOR]

Here graphene coating magnetite/N-doped carbon hybrid materials (G@Fe 3 O 4 /NC) have been synthesized. Structural characterizations revealed that Fe 3 O 4 /N-doped carbon was wrapped tightly and uniformly by graphene nanosheets via π-π interactions, which preventing the volume expansion of the material during the charge/discharge processes. G@Fe 3 O 4 /NC hybrid composites exhibited a large discharge specific capacity of 958 mAh g −1 after 65 cycles at a current density of 200 mA g −1 . [ABSTRACT FROM AUTHOR]

• Conducting polymer (polypyrrole)-intercalated V 2 O 5 is synthesized by a simple hydrothermal technique. • Polypyrrole enlarges the layer spacing of V 2 O 5 and forming a highway for ion diffusion. • Charge storage mechanism of Zn2+ and H+ co-intercalation layer is confirmed. • The electrode exhibits excellent electrochemical performance in aqueous zinc-ion batteries. Aqueous secondary zinc-ion batteries are promising candidates to replace lithium-ion batteries for large-scale energy storage, due to their high safety and low cost. However, the developed cathodes materials are facing low capacity or low cycle life due to sluggish diffusion kinetics. Therefore, the design of a cathode with ultrafast ion diffusion kinetics remains a great challenge. Here, we propose an in-situ intercalation strategy of polypyrrole to improve the cation diffusion kinetics of V 2 O 5. The polypyrrole as a guest significantly enlarges the interlayer spacing, paving the "superhighway" for cation diffusion. In addition, thanks to the unique π-conjugated structure, polypyrrole can shield the electrostatic force of Zn2+ and the host oxygen-sublattice. The energy storage mechanism of the cathode was shown to be a stepwise H+/Zn2+co-intercalation by means of galvanostatic intermittent titration technique (GITT), electrochemical impedance spectroscopy (EIS) and ex situ X-ray diffraction (XRD). Based on the above advantages, the polypyrrole-intercalated V 2 O 5 demonstrates high capacities and excellent cycling performance (220 mA h g−1 after 2000 cycles at 10 A g−1). We report an in-situ intercalation strategy of polypyrrole to improve the cation diffusion kinetics of V 2 O 5. The polypyrrole as a guest significantly enlarges the layer spacing, paving the "superhighway" for Zn2+ and H+ diffusion. [Display omitted] [ABSTRACT FROM AUTHOR]