Lithium-ion (Li-ion) battery pack is vital for storage of energy produced from different sources and has been extensively used for various applications such as electric vehicles (EVs), watches, cookers, etc. For an efficient real-time monitoring and fault diagnosis of battery operated systems, it is important to have a quantified information on the state-of-health (SoH) of batteries. This paper conducts comprehensive literature studies on advancement, challenges, concerns, and futuristic aspects of models and methods for SoH estimation of batteries. Based on the studies, the methods and models for SoH estimation have been summarized systematically with their advantages and disadvantages in tabular format. The prime emphasis of this review was attributed toward the development of a hybridized method which computes SoH of batteries accurately in real-time and takes self-discharge into its account. At the end, the summary of research findings and the future directions of research such as nondestructive tests (NDT) for real-time estimation of battery SoH, finding residual SoH for the recycled batteries from battery packs, integration of mechanical aspects of battery with temperature, easy assembling–dissembling of battery packs, and hybridization of battery packs with photovoltaic and super capacitor are discussed.

Intrinsically high lattice thermal conductivity has remained a major bottleneck for achieving a high thermoelectric figure of merit (zT) in state-of-the-art ternary half-Heusler (HH) alloys. In this work, we report a stable n-type biphasic-quaternary (Ti,V)CoSb HH alloy with a low lattice thermal conductivity κL ≈ 2 W m–1 K–1 within a wide temperature range (300–873 K), which is comparable to the reported nanostructured HH alloys. A solid-state transformation driven by spinodal decomposition upon annealing is observed in Ti0.5V0.5CoSb HH alloy, which remarkably enhances phonon scattering, while electrical properties correlate well with the altering electronic band structure and valence electron count (VEC). A maximum zT ≈ 0.4 (±0.05) at 873 K was attained by substantial lowering of κL and synergistic enhancement of the power factor. We perform first-principles density functional theory calculations to investigate the structure, stability, electronic structure, and transport properties of the synthesized alloy, which rationalize the reduction in the lattice thermal conductivity to the increase in anharmonicity due to the alloying. This study upholds the new possibilities of finding biphasic-quaternary HH compositions with intrinsically reduced κL for prospective thermoelectric applications.

Ternary intermetallic half-Heusler (HH) compounds (XYZ) with 18 valence electron count, namely, ZrCoSb, ZrNiSn, and ZrPdSn, have revealed promising thermoelectric properties. Exemplarily, it has been experimentally observed that a slight change in the content of Y site atoms (by ∼3–12.5% i.e., m = 0.03 and 0.125 in ZrY1+m Z) leads to a drastic decrease in lattice thermal conductivity κL by more than 65–80% in many of these compounds. The present work aims at exploring the possibility of maximizing the electronic transport scenario after achieving the low κL limit in these compounds. By taking into account the full anharmonicity of the lattice dynamics, Boltzmann transport calculations are performed under the framework of density functional theory. Our results show that these excess atoms present in the vacant lattice site induce scattering either by acting as a rattling mode or by hybridizing with the acoustic modes of the host depending upon their mass and bonding chemistry, respectively. Furthermore, the introduction of these scattering centers may lead either to the formation of a defect midgap state in the electronic band structure (detrimental for electronic transport) or to light doping of the host compound. The latter is found to be particularly conducive for attaining synergy in both thermal and electronic transport.

Predicting the lattice thermal conductivity (κL) of compounds prior to synthesis is an extremely challenging task because of complexity associated with determining the phonon scattering lifetimes for underlying normal and Umklapp processes. An accurate ab initio prediction is computationally very expensive, and hence one seeks for data-driven alternatives. We perform machine learning (ML) on theoretically computed κL of half-Heusler (HH) compounds. An exhaustive descriptor list comprising elemental and compound descriptors is used to build several ML models. We find that ML models built with compound descriptors can reach high accuracy with a fewer number of descriptors, while a set of a large number of elemental descriptors may be used to tune the performance of the model as accurately. Thereby, using only the elemental descriptors, we build a model with exceptionally high accuracy (with an R 2 score of ∼0.98/0.97 for the train/test set) using one of the compressed sensing techniques. This work, while unfolding the complex interplay of the descriptors in different dimensions, reveals the competence of the readily available elemental descriptors in building a robust model for predicting κL.

Ternary intermetallic half-Heusler (HH) compounds (XYZ) with 18 valence electron count viz. ZrCoSb, ZrNiSn, and ZrPdSn, have revealed promising thermoelectric properties. Exemplarily, it has been experimentally observed that a slight change in the content of Y-site atoms (by ∼3-12.5 % i.e., m =0.03, 0.125 in ZrY 1+m Z) leads to drastic lowering in the lattice thermal conductivity κ L by more than 65-80 % in many of these compounds. The present work aims at exploring the possibility of maximizing the electronic transport scenario after achieving the low κ L limit in these compounds. By taking into account the full anharmonicity of the lattice dynamics, Boltzmann transport calculations are performed under the framework of density functional theory. Our results show that these excess atoms present in the vacant lattice site induce scattering by acting either as a rattling mode or by hybridizing with the acoustic modes of the host depending upon their mass and bonding chemistry, respectively. Furthermore, the introduction of these scattering centers may lead to the formation of a defect mid-gap