Can, E. R. O. L.

Accurate state-of-charge (SOC) estimation remains a key challenge for lithium-ion batteries (LIBs) operating under varying thermal and load conditions, particularly in electric vehicles and grid-scale energy storage systems. Conventional model-based estimators such as EKF and UKF typically assume fixed parameters and neglect coupled electro-thermal dynamics, which degrades estimation accuracy under temperature fluctuations and aging effects. To address these limitations, this paper proposes a Thermal-Aware Hierarchical Self-Tuning Square Root Unscented Kalman Filter (TA-HST-SRUKF) for real-time SOC estimation. The proposed framework explicitly incorporates a lumped thermal model into the SOC estimation loop and employs a hierarchical self-tuning mechanism to adapt process and measurement noise covariances online. In addition, the square-root formulation enhances numerical stability and reduces computational burden, making the approach suitable for embedded battery management systems. Compared with conventional EKF- and UKF-based methods, the proposed TA-HST-SRUKF demonstrates improved robustness and accuracy across a wide temperature range and varying operating conditions. Simulation results confirm lower estimation errors and better adaptability without increasing computational complexity. The proposed method provides an effective and practical solution for highaccuracy SOC estimation in thermally dynamic and aging-prone battery applications.

Tuzluca Yesilbag, Fatma Nur; Yesilbag, Yasar Ozkan; Huseyin, Ahmad; Salih, Ahmed Jalal Salih; Ertugrul, Mehmet

The growing global demand for efficient and sustainable energy storage systems has intensified the need for advanced electrode materials with superior performance and stability. This study focuses on the synthesis and characterization of Fe2AlB2 MAB phase and Fe2Al1-xB2 MBene, highlighting their potential for energy storage applications. The Fe2AlB2 MAB phase was synthesized using FeB and Al powders via high-temperature sintering (1200 °C for 2 h), followed by selective etching of aluminum layers with a 2 M HCl solution to produce Fe2Al1-xB2 MBene. Electrochemical measurements demonstrated that Fe2Al1-xB2 MBene exhibits excellent pseudocapacitive behavior, achieving a specific capacitance of 276 F g−1 at 0.5 A g−1 in a three-electrode system. An asymmetric supercapacitor (ASC) configuration achieved an energy density of 20.6 Wh kg−1 at a power density of 306.4 W kg−1, with 96 % capacitance retention after 10,000 cycles. This research represents one of the pioneering studies on Fe2Al1-xB2 MBene, emphasizing its potential as a high-performance electrode material for next-generation energy storage devices. The findings provide valuable insights into the design and application of 2D MBenes for energy-related technologies.

Salih, Ahmed Jalal Salih; Huseyin, Ahmad

Efforts to enhance the properties of MXene have been ongoing since its discovery in 2011. Various strategies have been explored to improve its performance for many applications. One such strategy is doping MXene with heteroatoms. Doping has been studied for several applications, including supercapacitors, with particular attention given to nitrogen doping. This review focuses on doping MXene with nitrogen for supercapacitor applications. It discusses the effects of doping on the chemical, physical, and structural properties of MXene, the doping mechanisms (lattice substitution, functional substitution, and surface adsorption), and the contributions of each mechanism to the enhancement of electrochemical performance. Additionally, the review discusses doping methods and their impact on the performance of MXene as supercapacitor electrodes. It presents results from experimental studies and discusses several of these findings. Finally, it provides recommendations to guide future research and optimize outcomes in this field.

Colak, Tuluhan Olcayto; Altaf, Cigdem Tuc; Yesilbag, Fatma Nur Tuzluca; Yesilbag, Yasar Ozkan; Yildirim, Ipek Deniz; Erdem, Emre; Misirlioglu, Feray Bakan; Sankir, Nurdan Demirci; Sankir, Mehmet

Photo-supercapacitors (PSCs) have great potential as devices that enable both the conversion and storage of solar energy. However, it remains challenging to design new dual-acting electrodes providing high energy density and capacitance with self-powering capacity. Herein, we successfully prepared dual electrodes using ZnO-nanoflake and Ti3C2Tx-based MXene paper. By utilization of the MXene to the PSC device, capacitive contribution to the total capacitance increased ∼4 times compared to the bare ZnO-nanoflake-based PSC due to the surface redox reactions and electrically double layer formation. Maximum energy and power density of 57.3 μWhcm−2 and 11.1 mWcm−2, respectively were obtained for ZnO/MXene//MXene-PSC@UV irradiation and at a 2.5 V. Areal capacitance of this device calculated from CV was as high as 151.5 mFcm−2. Moreover, the ZnO/MXene//MXene-PSC device was highly stable over 10,000 GCD cycles with 100 % CE and 98 % Cp-retention under daylight.

Tuzluca Yesilbag, Fatma Nur; Huseyin, Ahmad

In this study, CuO nanowires were grown on copper foam (Cufoam) and copper foil (Cufoil) substrate with a cost-effective anodization method as core, and then MnCo2O4 nanowires were grown by hydrothermal synthesis method and three-dimensional (3D) core-shell nanowire arrays (NWAs) were obtained. The synthesized CuO NWAs, which provide a high surface area, contribute to the capacitance with the faradaic redox reaction and act as a current collector for the MnCo2O4 NWAs. Therefore, the 3D electrode design can increase the redox reaction, shorten the ions diffusion pathway, and exhibit low intrinsic resistance. The areal capacitance values of Cufoil/CuO, Cufoam/CuO, and Cufoam/CuO@MnCo2O4 electrodes were obtained at a current density of 0.5 mA cm−2 as 0.21, 1.02, and 2.82 F cm−2, respectively. The Cufoam/CuO@MnCo2O4 NWAs electrode exhibits excellent cycling stability of 97.3 % retention after 5000 cycles. In addition, an asymmetric supercapacitor (ASC) device was assembled by using the Cufoam/CuO@MnCo2O4 electrode and active carbon (AC) as the positive and negative electrodes, respectively. The ASC device operates in a potential range of 0–1.5 V and an energy density of up to 7.1 × 10−2 mWh cm−2 at a power density of 1.56 mW cm−2. This work may contribute to developing low-cost materials for energy storage devices.

Kalkan, Orhan

Today, Lithium-ion batteries are preferred as popular energy storage tools in many fields such as electronic devices, especially electric vehicles. During the discharge of modules and packs formed by combining many battery cells, undesirable temperature increases are experienced due to excessive heat generation. Thus, thermal management of the battery packs is crucial. In this work, thermal and hydraulic performance analysis of the two air-cooled 18650 NMC battery modules, one with a novel designed twisted busbar and the other with a conventional busbar, are performed numerically. Temperature and pressure drop predictions are achieved at different values of air inlet velocity, discharge rate, depth of discharge, and twist diameter of busbar using CFD method. Besides, the Multi-Scale Multi-Domain battery model is validated experimentally. According to the numerical results, the novel designed twisted busbar provides 1.84 %, 2.93 %, and 3.81 % reduction in maximum battery module temperature for 5 m/s air inlet velocity under discharge rates of 2C, 3C and 4C, respectively. The average battery module temperature drops by 6.6 °C thanks to the use of a twisted busbar. Using a twisted busbar results in a maximum pressure drop increase of 119 Pa compared to the conventional busbar. As the twist diameter of the busbar increases, the battery temperature decreases significantly, and the pressure drop increases, especially at high air velocity conditions. In addition, when the twist diameter increases from 5 mm to 15 mm, the weight/volume ratio increases by approximately 0.9 %.

Kalkan, Orhan

Immersion cooling offers promising advantages for cylindrical battery modules, particularly in applications where compact design, efficient thermal management, and enhanced safety are critical factors. In this study, the geometric, thermal, and dynamic parameters of an immersion-cooled battery module with 14 NCM cylindrical cells are analyzed using CFD methods. The developed battery model is experimentally validated, establishing the constraints through numerical analysis of the impact of design parameters on response values. The design parameters are optimized using a multi-objective optimization technique. The study models the battery module with mineral oil cooling and examines the impact of each parameter on variables such as maximum battery module temperature (Tmax), pressure drop (ΔP), maximum temperature variance (ΔTmax), and battery module mass index (Im). A Design of Experiment set, created with Central Composite Design (CCD), is solved using CFD methods, and quadratic correlation equations are derived using backward regression. The regression models for Tmax, ΔTmax, ΔP, and Im show high accuracy with R2 values close to 1.0. Optimization is performed using the entropy weight-based composite desirability function approach, yielding optimum values for cell center spacing (t), coolant mass flow rate (ṁc), and coolant inlet temperature (Ti) at 20.606 mm, 1.5 kg/s, and 23 °C, respectively. The optimized design sets are validated through CFD analysis, showing a maximum deviation of 4.27 %. Reducing t boosts thermal performance but lowers hydraulic performance, while the reverse occurs for ṁc. As Ti decreases, effective cooling improves, but temperature uniformity suffers.

Tuzluca Yesilbag, Fatma Nur; Yesilbag, Yasar Ozkan; Huseyin, Ahmad; Salih, Ahmed Jalal Salih; Ertugrul, Mehmet

3D structures obtained using 1D and 2D materials are promising materials in energy storage. Optimizing the interlayer spacing of 2D MXene through flexible conductive materials is an important step in synthesizing 3D composite electrodes. In this study, flexible and conductive MXene/BCN nanotube composite film electrodes were prepared by vacuum filtration using BCN nanotubes in different weight ratios (10 %, 20 %, and 30 %) in mixed and sandwiched structures. The mixed MXene/BCN10 (m-MX/BCN10) composite film electrode structure attained a specific capacitance of 678 F g−1, the highest of all tested electrodes, and exhibited remarkable cycle stability by retaining 95 % of its capacitance even after 10,000 charge/discharge cycles. In the symmetric supercapacitor (SSC), the cell exhibited a specific capacitance of 97 % after 10,000 charge/discharge cycles. Moreover, SSC showed an energy density of 32 Wh kg−1 and a power density of 11.5 kW kg−1. The composite electrodes made of 2D Ti3C2Tx MXene and 1D BCN nanotube materials open up a new avenue for synthesizing promising materials for energy storage in transition metal carbides and 1D nanotubes or nanowires.

Kalkan, Orhan; Colak, Andac Batur; Celen, Ali; Bakirci, Kadir; Dalkilic, Ahmet Selim

Since liquid-based thermal management systems are usually preferred methods for battery electric vehicles and cold plates are generally preferred to circulate the coolant, studies on their design are becoming increasingly essential. Besides, it seems useful to work artificial intelligence approaches to evaluate different battery thermal management systems, as it is known that the use of artificial intelligence is increasing in many applications today. The aim of this paper is to build up an artificial neural network model due to predict average battery temperature and maximum temperature difference on the battery surface which are also the artificial neural network outputs. The model inputs are depth of discharge, coolant flow rate (0.1, 0.6 and 1.1 l/min), discharge rate (1C- 5C), coolant inlet temperature (15, 25 and 35 °C). It is developed for a serpentine tubed cold plate, and mini channeled one which has novel design. To shorten the training time, after the optimization of the data set, a total of 270 data sets were utilized for training, validation, and test phases. In addition, the developed model predicts successfully average battery temperature and maximum temperature difference on the battery surface in the 10% error band range. Finally, the maximum margin of deviation and R values are 7.3% and 0.997%, respectively.

Yesilbag, Yasar Ozkan; Tuzluca Yesilbag, Fatma Nur; Huseyin, Ahmad; Ertugrul, Mehmet

This study investigated the specific capacitance, energy density and cyclic stability parameters of a WS2 coated vertically aligned BCN nanotubes (VA-BCN-NTs) composite electrode structure. The specific capacitance of VA-BCN-NTs was found to be 364 F g−1 at a current density of 0.5 A g−1. This electrode had 97% of their initial specific capacitance after 10,000 cycles at a current density of 20 A g−1, exhibiting excellent cyclic stability. In the three-electrode cell, the specific capacitance of the VA-BCN-NT@WS2 electrode at a current density of 0.5 A g−1 was calculated to be 690 F g−1. After 5000 cycles at a current density of 20 A g−1, the electrode structure had a capacitance value of 74%, showing good stability. In the two-electrode cell, the specific capacitance of the VA-BCN-NT@WS2 symmetrical supercapacitor at a current density of 1 A g−1 was found to be 170 F g−1. It was observed to have retained 85% of its capacitance after 10,000 cycles over a 1 V potential range. While the energy density of this structure was 23.6 Wh kg−1, the power density was 4250 W kg−1.