In the continuous demand for high-performance lithium-ion batteries (LIBs), thermal management control is, these days, crucial with respect to safety, performance, and longevity. As a promising passive solution, Phase Change Materials (PCMs) have been implemented to overcome the conventional battery thermal management (BTM) approaches, including air cooling, liquid cooling, or refrigerant-based systems. Their ability to transfer the heat during phase change processes makes them ideal candidates for further thermal buffers, thus allowing compact and energy-efficient temperature control without extra power consumption. This work encompasses the recent progress in PCM-based battery thermal management systems, with a particular focus on material selection, structural design, and experimental validation. Current advances in composite PCMs, including the use of high-conductivity additives, porous supports, and encapsulation methods, are here appraised in terms of their thermal conductivity, cycling stability, leakage prevention, and overall safety. Comparisons between organic, inorganic, and hybrid PCM types demonstrate the benefits and drawbacks of each class. Ongoing discussion is also directed towards challenges that include low thermal conductivity, limited heat storage capacity, scalability, cost, and flammability. Future development opportunities are also identified in the areas of multifunctional PCMs, hybrid passive–active cooling approaches, scalable processing, and life-cycle considerations.

In the automotive industry, ageing mechanisms and diagnosis of Li-ion batteries depending on charge rate are of tremendous importance. With this in mind, we have investigated the lifetime degradation of lithium-ion battery cells at three distinct charging rates using Electrochemical Impedance Spectroscopy (EIS). Impedance spectra of high-energy Panasonic NCR18650B batteries have been analysed in light of two distinct approaches, namely the time-dependent evaluation of the Constant Phase Element (CPE), and the single parameter investigation of resonance frequency of the circuit. SOH percentages were used to validate our approach. By monitoring the CPE-Q parameter at different charge rates of 0.5 C, 1 C, and 1.5 C, respectively, we applied a degradation speed analysis, allowing us to predict a quantitative value of the LIBs. The results are in complete agreement with the resonance frequency single parameter analysis, in which quite a similar trend was obtained after the spline fitting.

In this work, we employed an electrochemical impedance spectroscopy analysis of commercial Li-ion Panasonic NCR18650B cells in order to monitor their cycle life performance and the influence of the C-rate on the charge/discharge processes. By applying a fast charge rate of 1.5 C, we investigated their speed degradation within three distinct discharge rates, namely, 0.5 C, 1 C, and 1.5 C. In our first approach, we assessed the dynamics of the lithium-ion transport processes, as well as their dependence on discharge rates, with the aim of understanding how their performance correlates with usage conditions. We observed that, as the discharge current increases while the number of cycles decreases, the ohmic resistance in the aged state reduces. Moreover, the charge transfer resistance is not affected by the discharge current, as the values are inversely proportional to the current rate, but mostly by the number of cycles. By performing a state of health analysis of Li-ion batteries with different C-rates until they were completely discharged, we offer a clear indication of how much of the battery’s lifetime available energy was consumed and how much was left, anticipating further issues or when the battery needed replacing. Starting at 60% state of health, the battery degradation has a steeper increase at 0.5 C and 1 C, respectively, while for a deep 1.5 C discharge, it only increases when the battery charge rate can no longer be sustained. Finally, the resonance frequency results highlight a fast increase toward the end of life for 0.5 C and 1 C, which is directly correlated with the above results, as a potentiostatic electrochemical impedance spectroscopy sequence was applied every fourth charge/discharge cycle. When applied at 1.5 C, the linear trend is much more pronounced, similar to the state of health results.

By employing electrochemical impedance spectroscopy, we performed an impedance analysis of three commercial Li-ion Panasonic NCR18650B cells in order to investigate the direct effects of their internal impedance on the operating voltage, rate capability, and efficiency and their practical capacity. We aimed to assess their performance, safety, and longevity when distinct fast charge/discharge rates were applied. By maintaining a constant fast discharge rate of 2C, we monitored the degradation speed and the influence of the C-rates on the LIBs by applying distinct charge rates, namely, 1C, 1.5C, and 2C. In order to understand how their performance correlates with usage conditions, an SoH evolution analysis, together with a Q–Q₀ total charge and energy consumption examination, was performed, taking into account that cycling monitoring is vital for ensuring their longevity and/or safety. Increasing the I_charge from 1C to 1.5C reduces the battery lifetime by ~50%, while in the case of fast charge/discharge rates of 2C, the lifetime performance decrease is almost ~70% due to a capacity loss that accelerates quickly when the charge rates increase. Moreover, for the latter cell, the last discharge rate can only go up to ~80% SoH, as the battery charge rate can no longer support faster degradation. In agreement with these results, the fluctuations in the Q–Q₀ total charge become more pronounced, clearly affecting LIB efficiency. High charge rates add an additional high voltage that increases the batteries’ stress, leading to a shorter lifetime. Energy consumption data follow the same trend, in which efficiency decreases dramatically when losses appear because the internal resistance causes more and more heat to be produced during both fast charging and discharging.

Phase change materials (PCMs) have emerged as an innovative solution in thermal energy storage and thermal management systems (TMS) owing to their outstanding latent heat of fusion during the phase change process. This study is especially addressed to the battery TMS based on Organic PCMs for fast charging/discharging applications of lithium-ion batteries (LIBs). These fast processes generate excessive heat during operation, degrade battery performance, decrease energy efficiency, and reduce the lifespan and safety of batteries. Organic PCMs exhibit desirable properties, including high latent heat capacity, good thermal characteristics, low cost, and ease of integration. The major challenge for the successful application of organic PCM comprises its low thermal conductivity, which impacts the heat storage and release rates. PCM-based Paraffin Wax (PW) has been designed by including expanded graphite (EG) as a high thermal conductivity additive in high latent heat of paraffin wax. Experiments focused on the effects of heating methods (microwaves/S-type EG composition and conventional electric oven/S′-type EG composition) of expandable graphite on the thermophysical properties of different PW/EG composites. The crystal and chemical structure of the study samples were analyzed by X-ray diffraction and Fourier-Transform Infrared spectroscopy. The battery module created with PW/EG composites were ample examined using charging/discharging experiments at five different C-rates. The effect of current rates on battery surface temperature is investigated in two cases: with PCM cooling and with air cooling. A 20.43% decrease in battery temperature is found at 5C rate with PCM cooling and a maximum reduction in battery charging time of 43.77%.

All autonomous electrically powered devices require a continuous power supply from batteries. Increasing the discharge performance is the top priority in the Lithium-Ion (Li-Ion) battery field and pulsed discharge is proving numerous advantages. In this paper, the maximum efficiency of pulsed discharge method on a constant load while the cells are alternately switched with dead-time is thoroughly studied. Therefore, a novel Li-Ion charge/discharge and measurement device (SWD) using fast switching MOSFET was designed and fabricated. The device can alternately switch up to 8.3 kHz two Li-Ion 18650 batteries, generating continuous power to the programmable load and monitor the parameters that impact the capacity of the battery. An EIS (Electrochemical Impedance Spectroscopy) analysis is employed to evaluate the impedance and the behavior of the cells at frequencies up to 10 kHz. Experimental results reveal that a maximum discharge time is determined when two cells are switched at a frequency of 5.8 kHz. As a consequence, the total capacity of two switched batteries in a single discharge cycle is increased by 16.6%. Pulsed discharge efficiency is visible starting from 70% State of Charge (SOC) and is correlated with the rest time, reduced heat loss and inductance, respectively.