# Experimental and DFT study of the structural, electronic, and thermoelectrical properties of Li3xLa2/3-xTiO3 (x = 0.125) ceramic leads free for battery applications

Hicham Kacimi-Naciri, Meriem Ben Zennou, Assia Mabrouk, Amine El Azizi, Mohamed Loutou, Mohammed Mansori, Rachid Amrousse, Nadia Faska, Ahmed Bachar

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Hicham Kacimi-Naciri, Meriem Ben Zennou, Assia Mabrouk, Amine El Azizi, Mohamed Loutou, et al. Experimental and DFT study of the structural, electronic, and thermoelectrical properties of Li3xLa2/3-xTiO3 (x = 0.125) ceramic leads free for battery applications. Next Materials, 2026, 11, pp.101619. 10.1016/j.nxmate.2026.101619. hal-05488643

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Distributed under a Creative Commons CC BY 4.0 - Attribution - International License
Research article

Experimental and DFT study of the structural, electronic, and
thermoelectrical properties of Li₃xLa₂/₃-xTiO₃ (x = 0.125) ceramic leads
free for battery applications

Hicham Kacimi-Naciri<sup>a,b,*</sup>, Meriem Ben Zennou<sup>b,c</sup>, Assia Mabrouk<sup>b,e</sup>, Amine El Azizi<sup>g</sup>,
Mohamed Loutou<sup>g</sup>, Mohammed Mansori<sup>d</sup>, Rachid Amrousse<sup>f</sup>, Nadia Faska<sup>b,e</sup>,
Ahmed Bachar<sup>b,e</sup>

<figure><img src="image_2.png" /></figure>

ARTICLE INFO

Keywords:

LLTO perovskite

DFT

Dielectric

Thermoelectrical properties

Storage energy and battery applications

A B S T R A C T

We synthesized Li₃xLa₂/₃-xTiO₃ (LLTO, x = 0.125) via solid-state sintering, yielding a structurally stable orthorhombic perovskite with high environmental compatibility. The resulting material was characterized experimentally through X-ray diffraction (XRD), dielectric measurements (permittivity and loss), complex impedance analysis, and electrical conductivity testing. In parallel, first-principles computations using the BoltzTraP program and Density Functional Theory (DFT) were performed to determine the structural, electronic, and thermoelectric properties. Experimental results reveal a very high dielectric constant at low frequencies and high temperatures, with moderate dielectric loss behavior typical of ion-conducting perovskites. Nyquist plots demonstrate a significant decrease in impedance with increasing temperature, indicating enhanced mobility of Li⁺ ions. Electrical conductivity increases with temperature, exceeding 10⁻² S/m at 800 °C, and the ionic conduction activation energy is estimated to be ≈ 1.45 eV. Complementarily, DFT confirms structural stability and a 1.65 eV semiconducting band gap. BoltzTraP simulations highlight outstanding thermoelectric performance, with a Seebeck coefficient up to 4.5 µV/K at 500 K and ZT figure of merit approaching 1, increasing steadily with temperature—ideal for thermal-to-electric conversion. This work emphasizes ionic conductivity's crucial role in solid-state electrolytes: it directly impacts Li⁺ transport efficiency, thermal stability, and solid-state battery technologies' overall performance. Thus, LLTO's synergy of high ionic conductivity, mechanical/thermal stability, enhanced dielectric properties, and commendable thermoelectric positions it as a versatile material for next-generation solid-state Li-ion batteries and thermoelectric devices, as supported by recent research.

**1. Introduction**

In industries including information and communication technology,
transportation, healthcare, military, and security, electrochemical

storage devices are crucial to the advancement of cutting-edge tech-
nologies, which rely heavily on advanced battery systems [1–3]. To
meet the expanding demands of these industries, batteries must achieve
high energy density, safety, and long-term stability [4,5]. While

<footnote><sup>a</sup> Univ. Polytechnique Hauts-de-France, INSA Hauts-de-France, Laboratoire de Matériaux Céramiques et de Mathématiques (CERAMATHS), Valenciennes F-59313, France</footnote>

<footnote><sup>b</sup> Laboratoire Génie des Procédés (LGP), Faculté des Sciences, Université Ibnou Zohr, Agadir, Morocco</footnote>

<footnote><sup>c</sup> Univ. Polytechnique Hauts-de-France, Univ. Lille, CNRS, UMR 8520, IEMN - Institute of Electronics, Microelectronics and Nanotechnology, Valenciennes F-59313, France</footnote>

<footnote><sup>d</sup> IMED-Laboratory, Cadi Ayyad University, Morocco</footnote>

<footnote><sup>e</sup> Faculty of Applied Sciences - Ait Melloul, University Ibnou Zohr, Agadir, Morocco</footnote>

<footnote><sup>f</sup> University of Chouaib Doukkali, Faculty of Sciences, El Jadida 24000, Morocco</footnote>

<footnote><sup>g</sup> Laboratory of Molecular Chemistry, Pluridisciplinary Faculty of Nador, Mohammed Premier University, Morocco</footnote>

<footnote>* Corresponding author at: Univ. Polytechnique Hauts-de-France. INSA Hauts-de-France. Laboratoire de Matériaux Céramiques et de Mathématiques (CERAMATHS), Valenciennes F-59313, France.</footnote>

<footnote>E-mail address: Hicham.Kacimi-Naciri@uphf.fr (H. Kacimi-Naciri).</footnote>

<footnote>https://doi.org/10.1016/j.nxmate.2026.101619</footnote>

<footnote>Received 15 December 2025; Received in revised form 16 January 2026; Accepted 16 January 2026</footnote>

<footnote>Available online 22 January 2026</footnote>

<footnote>2949-8228/© 2026 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).</footnote>
traditional lithium-ion batteries using liquid electrolytes have driven significant progress, they face key limitations: low thermal and electrochemical stability, decreased ionic mobility at low temperatures due to higher solvent viscosity, and risks of thermal runaway, fire, or explosions from flammable organic solvents [6–9]. These issues affect battery safety and longevity, especially in harsh environments. As a solution, replacing liquid electrolytes with solid ones and promoting the development of all-solid-state batteries can address these challenges.

In recent decades, a variety of solid electrolytes, such as sulfides [10], polymers [11], oxides [12], etc. Among the main inorganic compounds are Li₃OX (X = Cl, Br) anti-perovskites, Li₇La₃Zr₂O₁₂ (LLZO)--based garnets, Li₀.₃₃La₀.₅₆TiO₃ (LLTO)-type perovskites (ABO₃) distinguished by transition metals at the B-site and alkali and alkaline earth metals at the A-site. In particular, lanthanum lithium titanate with the chemical formula Li₃xLa₂/₃-xTiO₃ has been found to have a high lithium ionic conductivity, making it one of the most promising solid electrolytes, high thermal and electrochemical stability, excellent mechanical properties, and non-toxicity [13–15]. Li-ion solid electrolytes of different perovskite types, including Li₃xLa₂/₃-xTiO₃ and (Li, Sr)(B, B')O₃ (B = Zr, Hf, Ti, Sn, Ga, etc., B' = Nb, Ta, etc.), have been developed in recent years [16].

The LLTO compound exhibits excellent dielectric properties, with an ionic conductivity reaching 3 × 10⁻⁴ S·cm⁻¹, rendering it appropriate for use as a solid electrolyte in thin films. Ahn and Yoon [17] deposited a (Li₀.₅La₀.₅)TiO₃ electrolyte film with a thickness of 360 nm using pulsed laser deposition (PLD) at 400–600 °C, achieving an ionic conductivity of 2 × 10⁻⁵ S·cm⁻¹·F. According to Tan et al. [18] prepared an LLTO thin film by magnetron sputtering, which exhibited a maximum ionic conductivity of 9.44 × 10⁻⁵ S·cm⁻¹ at 140 °C after optimized heat treatment. Similarly, Teranishi et al. [19] produced LLTO sheets that were around 411 nm thick, exhibiting an ionic conductivity of 4.42 × 10⁻⁵ S·cm⁻¹ after annealing at 1200 °C. To boost conductivity, Li⁺ ion concentration and mobility can both be raised. The material's chemical composition and crystal structure have a significant impact on these two variables. Mori [20] investigated the Li₀.₄La₀.₅₃TiO₃ material chilled using liquid nitrogen utilizing the bond-valence-sum method based on neutron diffraction data and inverse Monte Carlo simulation, and reported an activation energy (Eₐ) of approximately 0.269 eV (26 kJ·mol⁻¹). A subsequent review on LLTO [21] reported a similar value for Li₀.₃₄La₀.₅TiO₂.₉₄. More recently, Zaitouni et al. [22] studied the perovskite Li₀.₃₃+xLa₀.₅₅₇-xSrₓTi₁-xSnₓO₃ (LLSTS-x, x = 0.00–0.08) and demonstrated that the LLSTS-0.06 sample exhibited the best performance, with a low activation energy (Eₐ = 0.12 eV) and strong ionic conductivity (1.41 × 10⁻³ S·cm⁻¹ at 25 °C), due to a relative density of about 98 %. All doped compositions showed Eₐ values below 0.20 eV, confirming efficient and selective lithium-ion conduction. A shift in the Li conduction mechanism might be indicated by the variance in activation energy levels [23].

In spite of the substantial developments, the existing literature on bulk LLTO perovskites at x = 0.125 still shows a few crucial gaps. A majority of the research work is concentrated on thin films that are fabricated by highly sophisticated methods like pulsed laser deposition or magnetron sputtering [17,19], which exhibit positive conductivities but are limited due to nanoscale fabrication challenges and impracticability in scaling up for real devices. Although doped compositions such as LLSTS-x have shown improved low-temperature performance, detailed studies of undoped Li₃xLa₂/₃-xTiO₃ processed by simple solid-state sintering are scarcely available, especially dealing with the high-temperature dielectric response, bulk ionic transport mechanisms, as well as integrated thermoelectric potential. Moreover, even though the electronic structures have been probed by DFT, none of the earlier studies combined experimental dielectric/impedance analyses with BoltzTraP computations to thoroughly understand the relation between structural stability, ion conduction, and thermoelectric properties in this particular composition. Studying the behavior of semiconductor materials like LLTO at different temperatures is essential for various

applications [16]. Improving properties such as the Seebeck coefficient (S) [24], thermal conductivity (k), electrical conductivity (σ), and power factor (PF = S²σ) is also critical. The figure of merit (ZT), which measures how well a material converts thermal energy, is the basis for these evaluations [25]. Coupling theoretical findings of thermoelectric properties with experimental dielectric analysis provides a comprehensive understanding of the material's behavior under different conditions. Density Functional Theory (DFT) has been used to theoretically investigate the electrical structure and thermoelectric characteristics [26] implemented in the WIEN2k package [27], along with the BoltzTraP package [28] to facilitate thermoelectric calculations. This work closes these gaps by LLTO (x = 0.125) solid-state synthesis, extensive experimental characterization (XRD, permittivity, impedance, conductivity), and first-principles DFT+ BoltzTraP simulations, thus unveiling its potential as a multifunctional, environmentally-friendly material for cutting-edge energy storage and conversion technologies. Also In this study, we synthesized and characterized a Li₃xLa₂/₃-xTiO₃ perovskite system with a doping level of x = 0.125. The material's dielectric and electrical transport characteristics were the main subjects of our inquiry, with experimental measurements conducted to evaluate its conductivity. We observed that electrical conductivity increases with temperature. Furthermore, we examined the other related dielectric parameters, including activation energy and dielectric loss. Additionally, we integrated a theoretical component for the first time within this system by analyzing the structural, electronic, and especially the Seebeck coefficient, thermal conductivity (k), and thermoelectric properties as a function of temperature, electrical conductivity, and thermal capacity. The Seebeck coefficient and electrical conductivity were two examples of the qualities that were calculated and evaluated in this investigation, in relation to temperature effects. When combined with the experimental data on conductivity and dielectric behavior, this data provides insightful information on the characteristics of the substance and its potential applications across various domains such as battery technology [29], rendering this work original and significant for the advancement of Li₃xLa₂/₃-xTiO₃ structure [30].

## 2. Material and methods

### 2.1. Experimental part

Li₃xLa₂/₃-xTiO₃ ceramic solid solutions (x = 0.125) were created at high temperatures using a conventional solid-state sintering method. 99.8 % pure lithium nitrate (LiNO₃) from Alfa Aesar was used in the process. 99 % pure lanthanum trioxide (La₂O₃) from Alfa Aesar. and 99 % pure Sigma Aldrich's titanium dioxide (TiO₂). Following a thorough examination of the literature on ceramic synthesis, which informed the optimization based on previous research results, this process was developed in our lab. According to the following reaction:

$$ (3x) LiNO_3 + (2/3-x) La_2O_3 + TiO_2 \rightarrow Li_3xLa_{2/3-x}TiO_3 + NO_2\uparrow \quad (1) $$

Using an agate mortar, we initially measured the masses of the precursors prior to conducting a simple grinding process in 1 h. After that, the crushed powder was calcined for eight hours at 1100 °C in an alumina crucible. The resultant powder then went through a second grinding for one-hour. Then we fabricate the pallets, when sintering requires the powder to be effectively compressed. The procedure for making pellets with a press is explained below. Uniaxial pressure is the application of an axial mechanical force to a material in order to improve its density and compactness. 10 tons of pressure were applied to 0.300 mg of material for five minutes. The pallets were sintering at 1200 °C for 12 h. After that, the sintered pellets were ready for conductivity testing and XRD characterization. The material also needed to undergo further impedance analyses.
## 2.2. Theoretical part

Our ab initio calculations are essential for predicting the electronic, structural, and thermoelectrical properties of these materials. The WIEN2K code [26] employed the Density Functional Theory (DFT)-based full potential linearized augmented plane wave (FP-LAPW) techniques [31]. For the transport properties or thermoelectrical properties were carried out using BoltzTraP code [28]. For the purpose of exploring the thermoelectric properties, The BoltzTraP approach may be used to solve the semi-classical (Boltzmann) transport equation at constant relaxation time [28]. The BoltzTraP technique was used to calculate the electrical conductivity (σ), thermal conductivity (K), and Seebeck coefficient (S). Since S is independent of relaxation time (τ), σ and κ are also expressed in τ units. Using the Gibbs2 method [32], which was coupled with the WIEN2k software. Our calculation was performed by using the dew-Burje-Ernzerhof Generalized Gradient Approximation (GGA-PBE) method [33], local density approximation (LDA-CA-PZ) [34]. Common for metal perovskites due to their accuracy and computational cost in WIEN2k. LDA underestimates lattice parameters, while GGA matches experimental data better, allowing more reliable validation. This choice ensures reproducibility, as these standard functions are unique and influenced by LLTO and ionic electrolytes. La, Li, Ti, and O were calculated using atomic sphere radii (Ri) of 2.11, 1.48, 1.89, and 1.71 a.u. $Li_{3x}La_{2/3-x}TiO_{3}$ (LLTO), an orthorhombic perovskite, has a space group of Pmmm (no. 47). where c = 7.7850(Å), a= 3.8750(Å), b= 3.8760(Å) and 90.0000 for Alpha (°), 90.0000 for Beta (°), and 90.0000 for Gamma (°). The corner (0, 0, 0) fractional coordinates are occupied by the La atoms. The Ti atoms occupy the center of the orthorhombic structure's fractional coordinates (1/2. 1/2. 1/2). With the fractional coordinates (1/2. 0. 1/2), (1/2.1/2. 0), and (0.1/2. 1/2), the oxygen atoms filled the center face. 2\*2\*1 supercell has been used to illustrate doping with Li atoms. Replacing La atoms by Li atoms. For the optimization structure, the Monkhorst-Pack of the Brillouin k-point mesh is selected to be 1500Kpoint with a dense k mesh (10 × 10 × 10), the $G_{max}$ parameter is set to 12, and the calculation of the different properties structural, electronic, optic and thermoelectric are 3000K-point. The computations are repeated until self-consistency with the given energy convergence criteria is attained.at 0.0001 Ry. A value of -7.0 Ry was chosen as the energy required to separate the valence and core states.

# 3. Discussion

## 3.1. Experimental results

### 3.1.1. Diffraction de rayon X (XRD)

Phases were identified using X-ray diffraction with copper radiation (k = 1.54187 Å). Data were collected in Bragg-Brentano geometry having a step size of 0.010° 2θ, a collection time of 100 s each step, and an angular range of 20° to 80° 2θ.

Clear displays of the sample's XRD pattern in Fig. 2. Most reflections

<figure><img src="image_3.png" /><figcaption>Fig. 1. $Li_{3x}La_{2/3-x}TiO_{3}$ (LLTO) structure with a 2\*2\*1 supercell.</figcaption></figure>

<figure><img src="image_4.png" /><figcaption>Fig. 2. Synthesized X-ray diffraction pattern of LLTO ceramics (x = 0.125).</figcaption></figure>

across all compositions can be indexed to and the orthorhombic structure (Pmmm). Notably, the sample's XRD pattern for the stoichiometric composition LLTO with x = 0.125 reveals the coexistence of two phases within the structure. The X-ray diffraction (XRD) pattern of (LLTO), along with its indexed (hkl) planes, clearly indicates the excellent phase purity and crystallinity of the produced ceramic material. The primary diffraction peaks are associated with specific lattice planes, which include (110), (111), (101), (112), (002), (121), (212), and (220). The structural analysis following LeBai refinement indicates that the space group Pmmm, LLTO crystallizes in the tetragonal phase. With α = β = γ (°) = 90°, the revised lattice parameters are a = 3.88367 Å, b = 3.87202 Å, and c = 7.74693 Å. Table 1, which aligns with previously reported values [36]. The prominent (110) peak shown near 2θ ≈ 32.6289° can be taken as a fingerprint of a layered perovskite structure, thus suggesting that a significant amount of texturing or preferential orientation is present [37]. Besides that, the formation of sharply resolved peaks at several other positions confirms the creation of the single-phase material, thereby eliminating the possibility of impurities or amorphous phases. Additionally, the pointiness and power of the peaks indicate that the crystallite size is good and the defect density is low, thus the structure is strong enough to be used in advanced electrochemical and thermoelectric applications. The present pattern agrees with the published data [23], which used (hkl) indices to confirm the structure and phase of LLTO materials.

### 3.1.2. Dielectric properties

Dielectric constant Fig. 3. demonstrates how the dielectric constant (e') changes with temperature as a function of frequency (600°C to 800°C). This highlights the typical dielectric behavior of all-solid-state Li-ion batteries using a solid electrolyte of the perovskite type. The value of e' is very high at low frequencies and decreases rapidly with increasing frequency. This behavior reflects the contribution of several polarization mechanisms present in the material [38]. At low frequencies, below 10 Hz, the dielectric constant reaches very high values (up to around 4.5 × 10⁷ at 800°C), exhibiting strong interfacial polarization, or Maxwell-Wagner-Sillars polarization [39]. This phenomenon is characteristic of polycrystalline materials in which ionic conduction is hindered at the interfaces between grains or the electrode/electrolyte interface, accumulating charges at these locations [40]. In lithium-conducting perovskite materials, this accumulation is enhanced by crystalline defects such as lithium or oxygen vacancies, a heterogeneous microstructure, and higher temperature-induced Li ion mobility [41]. As the frequency increases, particularly above 10² Hz, there is a clear decrease in dielectric constant. This phenomenon reflects the diminishing ability of lithium ions and dipoles in the structure to follow
<table><caption>**Table 1**
Lattice parameters and tetragonality of lithium-doped LLTO structure.</caption><thead><tr><th>Parametres</th><th>a(Å)</th><th>b(Å)</th><th>c(Å)</th><th>α= β= γ(°)</th><th>G. E</th><th>Volume(Å<sup>3</sup>)</th></tr></thead><tbody><tr><td>LLTO This study</td><td>3.88367</td><td>3.87202</td><td>7.74693</td><td>90°</td><td>Pmmm(47)</td><td>116.757</td></tr><tr><td>References</td><td>3.875 [23]</td><td>/</td><td>7.739 [23]</td><td>90°</td><td>P4/mmm[23]</td><td>/</td></tr><tr><td></td><td>3.864 [35]</td><td>3.875[35]</td><td>7.786[35]</td><td></td><td>Pmmm[35]</td><td></td></tr></tbody></table>

References: [23,35].

<figure><img src="image_5.png" /><figcaption>**Fig. 3.** Dielectric constant (ε') versus frequency at 600°C, 650°C, 700°C, 750°C, and 800°C temperatures.</figcaption></figure>

rapid variations in the applied electric field [42]. In this frequency range, orientation polarization becomes ineffective, and only contributions from faster processes, such as electronic or vibrational responses of the crystal lattice, remain [43]. Above 10⁴ Hz, the dielectric constant tends towards a quasi-constant value, illustrating the material's intrinsic dielectric response, independent of ionic migration phenomena. Furthermore, the effect of temperature is very marked on all curves. A significant increase in dielectric constant ε' is observed with temperature, regardless of the frequency domain. This evolution results mainly from the thermal activation of Li⁺ ions, which promotes their mobility in the crystal lattice [44]. Rising temperature also. This analysis confirms that the perovskite material features a highly temperature-dependent jump ion conduction mechanism with a well-defined activation energy. For applications like solid-state lithium-ion batteries, this trait is crucial to ensuring optimal performance, where temperature-controlled ion mobility conditions the energy efficiency and stability of the device, improving interfacial polarization by facilitating ionic conduction across interfaces, while enhancing the participation of mobile defects such as lithium vacancies [45]. This behavior highlights a thermally activated ionic conduction type dominated by “hopping” type mechanisms, in which ions migrate by successive hops between crystalline sites, due to polarization [46].

**Dielectric loss** Fig. 4. demonstrates how dielectric loss (tan δ) varies with frequency at various temperatures (from 600°C to 800°C). This reveals essential information about the energy dissipation mechanisms in lithium-conducting perovskite material. The loss factor reflects the proportion of electrical energy converted to heat when an alternating field is applied and thus reflects relaxation or conduction processes within the material [47]. Dielectric losses remain moderate and relatively stable at low frequencies (below 10 Hz), particularly when the temperature is high. An buildup of charges at the interfaces is the cause of this (Maxwell-Wagner-Sillars polarization), with little dynamic relaxation, but a significant contribution from DC conduction [48]. However, at lower temperatures (such as 600°C or 650°C), tan δ exhibits relatively high values even at low frequencies, indicating higher losses

<figure><img src="image_6.png" /><figcaption>**Fig. 4.** Dielectric loss (tan δ) versus frequency at 600°C, 650°C, 700°C, 750°C, and 800°C temperatures.</figcaption></figure>

associated with low ion mobility and less efficient conduction [49]. As frequency increases, tan δ follows a characteristic evolution with the appearance of well-marked peaks, whose position shifts towards higher frequencies with increasing temperature. The dielectric relaxation processes linked to the charge carriers' delayed reaction are represented by these peaks (Li⁺ ions or defects) to the applied alternating field [50]. The shift of peaks towards higher frequencies with increasing temperature indicates an enhancement of ionic mobility: Li⁺ ions can respond more rapidly to field alternation thanks to thermal activation [51]. This behavior is typical of hopping-type ion transport mechanisms [52]. The height of the tan δ peak also grows as the temperature rises, peaking at 800°C. This reflects an intensification of losses due to the simultaneous increase in ionic conduction and defect activity (vacancies, interstitials) [53]. Losses drop sharply at high frequencies (above 10⁵-10⁶ Hz), suggesting that charge carriers can no longer follow rapid field oscillations and that only electronic or vibrational polarizations persist [54].

**Complex impedance analysis** Fig. 5 shows Nyquist diagrams (—Z'' vs Z') obtained for the Li⁺ conductive perovskite-type solid electrolyte, analyzed between 600 and 800 °C in temperature. These curves highlight the complex electrochemical response of the material, directly linked to internal ionic conduction mechanisms [55]. Each curve features characteristic semicircular arcs whose shape and position vary with temperature. These Nyquist plots are typical of ion-conducting solids and reveal several contributions to ionic transport, arising from the microstructural features of the material, namely, grains, grain boundaries, and electrode interfaces [56]. At 600 °C and 650 °C, the diagrams display broad, imperfect arcs with high values of real impedance (Z') and a pronounced imaginary component (Z''). Such wide arcs indicate substantial resistance to ionic motion, reflecting the relatively low mobility of Li⁺ ions at these lower temperatures. The distortion and depression of these arcs imply the presence of multiple relaxation processes, mainly due to the coexistence of intra-grain and inter-grain ionic transport phenomena [57]. As the temperature rises (700 °C, 750 °C, and 800 °C), the arcs progressively shrink and shift toward lower impedance values. This significant reduction in arc diameter suggests a
<figure><img src="image_7.png" /><figcaption>Fig. 5. Nyquist plots (-Z'' versus Z') at different 600°C, 650°C, 700°C, 750°C, and 800°C temperatures.</figcaption></figure>

marked decrease in the electrolyte's total resistance, consistent with thermally activated ionic conduction [58]. With rising temperature, Li⁺ ions acquire enough thermal energy through hopping processes to get across potential barriers between empty lattice sites, resulting in increased conductivity and decreased resistance [59]. At 800 °C, the Nyquist plot exhibits a highly flattened, nearly linear behavior, with very low Z' and Z'' values. This shape indicates an almost purely capacitive response and implies that ionic conduction is very efficient, with minimal blocking at grain boundaries or interfaces. The emergence of a quasi-rectilinear region may also correspond to interfacial polarization at the electrode/electrolyte boundary, typical of materials with excellent ionic transport properties [60]. The electrochemical behavior observed in Fig. 5 is well represented by the proposed equivalent circuit model, composed of two series-connected parallel RC elements. The first (R<sub>g</sub>, C<sub>g</sub>) models the bulk (grain) response, while the second (R<sub>gb</sub>, C<sub>gb</sub>) accounts for grain boundary effects. R<sub>g</sub> and R<sub>gb</sub> are high at low temperatures, explaining the large arc sizes and reduced conductivity. As temperature increases, the resistance values in both components diminish significantly, confirming improved conduction within grains and across grain boundaries [61]. This evolution directly supports the conclusions drawn from Figs. 3 and 4, which showed a high dielectric constant (e') at low frequencies as a result of polarization at the interface, and a temperature-dependent decrease in dielectric loss (tan δ)

<figure><img src="image_8.png" /><figcaption>Fig. 6. Electrical conductivity (σ) versus frequency at various temperatures (600°C, 650°C, 700°C, 750°C, and 800°C).</figcaption></figure>

peak positions, both signatures of enhanced Li⁺ ion dynamics.

**Electrical conductivity** Fig. 6 illustrates the evolution of the material's electrical conductivity (σ) as a function of frequency, measured over a wide range from 0.1 Hz up to 10 MHz, for temperatures ranging from 600°C to 800°C. This graph highlights the joint dependence of conductivity on frequency and temperature, which is characteristic of ionically conductive materials such as perovskite-type solid electrolytes [62]. At low frequencies, conductivity remains relatively stable and low, corresponding to continuous conduction limited by barriers to ionic transport, such as crystalline defects or grain boundaries. This zone is dominated by steady-state ion transport, where microstructural obstacles hinder the mobility of Li⁺ ions [63]. On the other hand, as frequency increases, conductivity rises significantly, reflecting a transition to a dynamic regime in which ions and polarizable dipoles can respond to fast alternating fields. This progressive increase is characteristic of dispersive conduction, where ionic hopping or local polarization mechanisms are activated [64]. The influence of temperature is particularly marked: electrical conductivity increases significantly with temperature over the entire frequency range. For example, at 800°C, conductivity exceeds 10⁻² S/m at high frequency, while at 600°C it remains lower, below 10⁻³ S/m. This trend highlights the thermally activated nature of ion transport, with Li⁺ ions benefiting from sufficient energy to more easily cross energy barriers in the crystal lattice at high temperatures [65]. Note also that the marked increase in σ at very high frequencies (above 1 MHz) may also reflect the contribution of electronic or vibrational polarization, faster mechanisms than ionic conduction. This confirms the complexity of electrical responses in this material and its ability to exhibit multiple phenomena depending on experimental conditions [66]. Fig. 5 is perfectly consistent with the results previously observed: the strong thermal activation of conduction, deduced from Nyquist diagrams (Fig. 4) and variations in dielectric constant (Fig. 3), and the ionic relaxation observed via dielectric losses (Fig. 3). Microstructure, notably the presence of grains and grain boundaries, is a key factor modulating these properties, confirmed by equivalent circuit analysis [67].

**Activation energy** Fig. 7 shows a semi-logarithmic plot of the Arrhenius model shows the relationship between electrical conductivity (log σ) and the inverse of absolute temperature (1/T). This makes it possible to evaluate the ionic conduction mechanism's activation energy (Eₐ) in the perovskite material studied. The remarkable linearity of the experimental points indicates that conductivity follows a thermally activated behavior, characteristic of ionic transport governed by Li⁺ ion

<figure><img src="image_9.png" /><figcaption>Fig. 7. Arrhenius plot of log(σ) versus reciprocal temperature (1/T) with activation energy (Ea) determination.</figcaption></figure>
hopping between crystallographic sites. This exponential dependence confirms that the primary mechanism is ionic migration across lattice energy barriers, which is highly sensitive to temperature [65]. Calculating the slope of the linear line yields an activation energy Ea of around 139.78 kJ/mol (i.e., approx. 1.45 eV). This relatively high value suggests that conduction is limited by significant energy barriers, such as defects, oxygen vacancies, or grain boundaries, which require substantial thermal energy to overcome [68]. This activation energy is consistent with previous observations: the decrease in resistance at high temperature in the Nyquist diagrams and the marked increase in electrical conductivity testify to the predominant role of thermal activation in facilitating the movement of lithium ions [69]. It also corroborates the dielectric relaxation phenomena highlighted by losses, where ion dynamics accelerate with temperature. This analysis confirms that the perovskite material features a highly temperature-dependent jump ion conduction mechanism with a well-defined activation energy [70]. For applications like solid-state lithium-ion batteries [71], this trait is crucial to ensuring optimal performance, where temperature-controlled ion mobility conditions the device's energy efficiency and stability [72].

## 3.2. Theoretical results

Before calculating the many properties of these intricate structures, the first stage in the computation is to optimize the structure using a variety of strategies and tactics, as explained in the Materials and Methods section (LDA, GGA-PBE). This optimization step is crucial to ensuring accurate and reliable outcomes in subsequent research. The partial density of states (PDOS) and total density of states (TDOS), band structure (eV), and other electrical properties can provide important information about the material's physical features, especially its bonding nature. It is crucial to analyses the LLTO structure's bonding properties in detail. Applying the GGA technique. We estimated the band structure, computed the thermoelectric properties using Boltztrap, and assessed the partial and total densities of states (PDOS and TDOS) in order to fully understand the bonding processes found in these compounds.

### 3.2.1. Electronic and structural properties

The presented result of the structure $Li_{3x}La_{2/3-x}TiO_3$ ($x = 0.125$) was performed using the exchange-correlation potential method GGA-PBE. In the Table 2 were given the different parameters of the structure after optimization such as the lattice parameters (a, b, c), both the electrical band structure and the structure's density.

The Table 2 gives a thorough summary of the crystal structure and key physical characteristics for the lithium lanthanum titanate compound (known as LLTO), it is acknowledged as a potential solid-state electrolyte for cutting-edge lithium-ion batteries and associated electronic applications. Its lattice constants ($a=3.865 Å, b=3.876 Å, c=3.892 Å$) show a nearly cubic symmetry with minor tetragonal distortion ($c/a=1.006$), correlating with its perovskite crystal structure and the highly symmetric $Pmmm$ space group, which favors ionic conduction and mechanical robustness. The measured density (4.637 g/cm$^3$) reveals a tightly packed ceramic, while its electronic band gap ($E_g =1.653 eV$) places LLTO in a regime suitable for semi-conductive behavior [74], helpful in minimizing electronic leakage while allowing efficient lithium-ion transport [75]. These combined characteristics

are vital for the well-known use of LLTO as a solid-state electrolyte in lithium batteries, where high density, robust mechanical properties, and moderate band gap contribute to high conductivity and improved electrochemical performance, making it a subject of continued research and significant technological interest [76].

The band structure gives important information about the energy and momentum characteristics of a material by defining how electrons behave and occupy different states. To figure out the electrical and structural characteristics of the pure and doped structures, we measured the band gap of the different structures using the GGA-PBE method. The band profile of orthorhombic structure of lithium titanate oxide perovskites (LLTO), this comprises the first highly symmetric Brillouin zone, as shown in the Fig. 8 is the detailed result of the PBE (Perdew-Burke-Ernzerhof) method, which is a common functional within density functional theory (DFT). The picture reveals the valence and conduction bands and also points out the band gap area, this represents the energy differential between the electronic states that are most and least occupied. In the case of LLTO, DFT calculations generally yield a band gap of about 1.65 eV [75], which approaches the experimental value fairly closely, although PBE is known to underestimate the real gap slightly due to its way of handling electron exchange and correlation. Such a band gap characterizes LLTO as a wide-gap semiconductor [77], thus it can be a good lithium-ion conductor with very little electronic leakage, which is an essential feature for a solid electrolyte in a battery. The PBE method in DFT studies is computationally efficient but may undervalue band gaps when compared to more accurate methods (hybrid functionals). Still, the band structure based on PBE serves as a helpful prediction tool for the material's electronic features and demonstrates how the insertion of lithium or doping can influence electronic conductivity and magnetic properties [21]. Several references confirm these results, indicating that the band structure of LLTO is favorable for ionic mobility and a stable electronic state is maintained, with the band gap and conduction properties being the main factors determining the material's use in energy storage and solid-state electrolyte fields [78].

The calculated band gap of LLTO not only corroborates the electronic structure analysis but also aligns with findings from previous studies.

<figure><img src="image_10.png" /><figcaption>Fig. 8. The band gap of LLTO, as determined using the PBE method.</figcaption></figure>

<table><caption>**Table 2**
The structure's electrical band structure, density and lattice characteristics of LLTO.</caption><thead><tr><th>Parametres</th><th>a(Å)</th><th>b(Å)</th><th>c(Å)</th><th>α= β= γ(°)</th><th>G. E</th><th>Density (g/cm³)</th><th>Eg(eV)</th></tr></thead><tbody><tr><td>Li<sub>3x</sub>La<sub>2/3-x</sub>TiO<sub>3</sub> (x = 0.125)</td><td>3.865</td><td>3.876</td><td>3.892</td><td>90°</td><td>Pmmm (47)</td><td>4637</td><td>1.653</td></tr><tr><td>References</td><td>3.875 [23]<br>3.864 [35]<br>3.870 [35]<br>3.864 [73]</td><td>/<br>3.875[35]<br>/<br>3.875[73]</td><td>7.739 [23]<br>7.786 [35]<br>7.740 [35]<br>7.786 [73]</td><td>90°<br>90°<br>90°<br>90°</td><td>P4/mmm [23]<br>Pmmm [35]<br>P4/mmm [35]<br>P4/mmm [73]</td><td>/</td><td>/</td></tr></tbody></table>

References: [23,35,73].
Refs [79–81]. Researchers have observed analogous band gap values and dispersion features in perovskite-type lithium titanate oxides, confirming their classification as wide-gap semiconductors. The retention of a relatively large band gap following structural modification or doping indicates that the material is likely to exhibit limited electronic conductivity, a critical characteristic for solid electrolyte materials. The consistency of these results with prior density functional theory (DFT) studies reinforces the robustness of the LLTO structure, further validating its suitability for lithium-ion transport and applications in solid-state batteries.

By providing conformance with the band structure data, an examination of the density of states (DOS) further clarifies the electrical features. The DOS, a representation of the number of electron-accessible states at various energy levels, may be used to measure the number of electronic levels per unit volume per unit energy. For the materials' LLTO doped structures, we calculated the total and partial densities of states (TDOS and PDOS). The structure's PDOS for the several elements (La, Li, Ti, and O). The DOS (Density of States) and TDOS (Total Density of States) plot for LLTO, which were computed using the PBE technique, provide an accurate representation Fig. 9 of how certain atoms La and Li affect the electrical structure. The TDOS shows the total electronic states, while the colored curves (representing La, Li, Ti, and O) indicate the contribution of each element. A red dashed line at 0 eV represents the Fermi level (E.F.), and the fact that no significant states cross this line is band gap evidence which makes LLTO a semiconductor [77]. The energy reference point in the density of states diagram of LLTO is the Fermi level, below which most states are assigned to oxygen 2p orbitals, and small contributions are made by lanthanum and titanium near the valence band edge. Above the Fermi level (positive energy), a sharp peak due to titanium Ti-3d dominates the conduction band, while lithium and lanthanum have minor influences overall. This DOS structure is a solid one to the idea that electronic conduction is kept at a minimum, while LLTO is a large band gap solid electrolyte with no states at the Fermi level, making it very suitable for advanced lithium battery applications. These interpretations are consistent with DFT studies of perovskite materials, where the O-2p and Ti-3d orbitals define the critical regions for electronic transitions and explain the material’s ionic conductivity and electrochemical stability [23].

The electronic structure of LLTO, as revealed by TDOS and PDOS calculations, aligns well with previous theoretical and experimental findings published in Refs. [79–81]. The valence band is primarily composed of O-2p states, consistent with these studies, while the conduction band is dominated by Ti-3d orbitals. This confirms the semiconducting nature and large band gap of LLTO. Furthermore, the

<figure><img src="image_11.png" /><figcaption>Fig. 9. The DOS of LLTO of various elements in the structure were determined using the PBE method.</figcaption></figure>

absence of electronic states at the Fermi level-also observed in other perovskite systems-highlights the excellent electronic insulation and structural stability of LLTO, which are key characteristics for its application as a solid electrolyte in next-generation lithium-ion batteries.

### 3.2.2. Thermoelectric properties

Thomas Seebeck et al. [82]. created the BoltzTraP code in this section. Is typically used to investigate the thermoelectric characteristics. By transforming excess heat into usable energy, it aids in the exploitation of lost energy. Finding a prospective thermoelectric that is both eco-friendly and appropriate for the material is essential to producing green energy from waste heat. To produce this type of energy, scientists and industrialists are primarily focused on this. The dimensionless ZT value, which is provided by the following formula, is used to characterize the thermoelectrical material's efficiency:

$$ZT = \frac{S^2 * \sigma}{\kappa} T \quad (2)$$

Where S represent the Seebeck coefficient (V/K), σ (Ω.m.s)⁻¹ represent the electrical conductivity and κ (Wm⁻¹K⁻¹s⁻¹) indicate the overall thermal conductivity, taking into account the lattice and electron contributions.

**Seebeck coefficient (S):** The Fig. 10. (a) given give a break-down of the manner in which the temperature modifies the thermoelectric features of the LLTO structure. The Seebeck coefficient (S) is first of all, seen to go up continuously with temperature. This behavior is typical of materials in which the thermal excitation makes more symmetrical the carriers of charge around the Fermi level and, thus, leads to a more significant generation of thermoelectric voltage at high temperatures. The increment is generally associated with an enhancement of the carrier energy gradient and is highly desirable in complex oxides for effective heat-to-electricity conversion [83]. The Seebeck coefficient is the central factor that determines the thermoelectric response. It is a measure of how well charge carriers can produce an electrical voltage from a temperature gradient. Consistently with these recent findings, changes in the Seebeck coefficient are directly associated with alterations in the electronic structure and the carrier concentration caused by the compositional modification. Generally, a large Seebeck coefficient is the signature of a favorable energy-dependent carrier transport that is the crux of the thermoelectric performance improvement. Furthermore, if relatively high Seebeck values are preserved as showed in our study while enhancing electrical conductivity, one can realize a higher power factor. Hence, the Seebeck features obtained in this work reveal that the studied compound has a great potential for thermoelectric, especially in energy conversion devices driven by a temperature gradient [84–86].

**Electrical conductivity (σ) at the same time, to a higher value with temperature; thus, this is an indication of a material where the thermal activation of the carriers' mobility or concentration results in the lowering of the diffusion and crystal order barriers. The appliances, in which the objective is to reduce ohmic losses to the minimum and at the same time to maximize the yield, will be able to take great advantage of this kind of performance [87] Fig. 10. (b). A key aspect in thermoelectric materials is electrical conductivity (σ), which directly affects the figure of merit and power factor by reflecting the effectiveness of charge carrier movement. Prior research has demonstrated that carrier concentration and mobility, which may be successfully adjusted by compositional alteration and structural optimization, greatly regulate electrical conductivity which confirms our investigation [84–86]. The measured electrical conductivity behavior in this study shows enhanced charge transport while keeping the Seebeck coefficient in a tolerable balance. The potential of the material under investigation for useful thermoelectric energy conversion applications is supported by this balance, which is crucial for improving the overall thermoelectric performance.

**Thermal capacity C<sub>v</sub> (c):** The heat capacity (C<sub>v</sub>) exhibits a rapid and almost linear growth over the whole temperature range that was
<figure><img src="image_12.png" /><figcaption>**Fig. 10.** Temperature-dependent variation of LLTO's thermoelectric properties (Seebeck S (a), electrical conductivity σ (b), thermal capacity Cv (c), and power factor P.F. (d)).</figcaption></figure>

investigated. This indicates that the LLTO structure is becoming able to store more energy in the form of heat, which is a manifestation of the increase in the vibrational degrees of freedom and the growing contribution of phonons to energy storage [88]. This phenomenon is central to understanding thermal transport and material expansion under thermal stress [89] Fig. 10. (c). In thermoelectric materials, the thermal capacity is crucial because it indicates a material's potential to store heat and affects its thermal response under working circumstances. Recent research has shown that changes in thermal capacity are intimately linked to bonding properties and lattice dynamics, which have an immediate impact on heat transport behavior [84–86]. In order to ensure thermal stability and an adequate temperature differential across the material, a moderate thermal capacity is advantageous. For thermoelectric devices working under continuous or cyclic thermal circumstances, the derived thermal capacity values in the current study show strong thermal management capabilities, which indirectly contributes to the total thermoelectric efficiency.

**The power factor (PF):** a fundamental factor for thermoelectric efficiency, increases significantly with temperature. Given that it is dependent on both electrical conductivity and the Seebeck coefficient, the synchronized growth of these two properties leads to an efficiency optimized at high temperature, which is considered as the most important for the design of thermal energy recovery modules [88]. This potential efficiency is also associated with the low intrinsic thermal conductivity, which is often desired in this type of material, thus a strong thermal gradient can be maintained and the figure of merit (ZT) can be

increased [90] Fig. 10. (d). The power factor (PF = S²σ) is a crucial parameter for assessing the electrical contribution to thermoelectric performance, as it combines the effects of the Seebeck coefficient and electrical conductivity. According to recent studies [84–86] that confirm our approach. Optimizing carrier concentration and mobility often results in a higher power factor by improving the balance between electrical conductivity and the Seebeck coefficient. In the present work, the obtained PF values indicate efficient charge carrier transport while preserving adequate thermopower, leading to improved electrical power generation capability. This enhancement of the power factor highlights the suitability of the investigated material for thermoelectric applications, particularly in devices where high electrical output under a temperature gradient is required.

**Figures of merit (ZT):** The figure of merit for thermoelectric materials (ZT), as defined by Eq. 2, shows the highest energy conversion efficiency for power generation and cooling at a given temperature. The (ZT) parameter is influenced by the material's electrical conductivity and Seebeck coefficient.

**Fig. 11** clearly illustrates a progressive and continuous increase in the ZT value with rising temperature, suggesting that the thermoelectric performance of LLTO enhances as temperature increases [91]. The simultaneous rises in the Seebeck coefficient are consistent with this pattern, electrical conductivity, and power factor previously observed, all of which positively contribute to the thermoelectric figure of merit. Achieving a dimensionless figure of merit (ZT) close to 1 is regarded as indicative of excellent performance for thermoelectric materials [89],
<figure><img src="image_13.png" /><figcaption>**Fig. 11.** Figures of merit (ZT) of the LLTO structure that vary on temperature utilizing the Boltztrap package.</figcaption></figure>

thereby supporting the proposition that lanthanum lithium titanate (LLTO) is a promising candidate for energy conversion applications utilizing thermal sources at moderate to high temperatures [92]. These findings are consistent with prior literature that suggests that complex oxides, such as LLTO, can attain ZT values in the range of 0.5–1 within comparable temperature intervals, thus underscoring their potential utility in industrial waste heat recovery systems and sustainable applications [93]. In this context, the obtained ZT values in the present work reflect the combined effect of improved electronic transport and reduced thermal losses, indicating an efficient coupling between electrical and thermal properties according to some references that confirms our approach [84–86]. Such behavior demonstrates that the investigated material is a promising candidate for thermoelectric energy conversion applications, particularly for waste heat recovery and low-to-intermediate temperature thermoelectric devices.

Due to their favorable electronic structure and transport characteristics, recent first-principles investigations [94] have identified certain compounds as exemplary candidates for thermoelectric and optoelectronic applications, paralleling the focus of our research. These materials demonstrate significant potential for energy harvesting devices, where efficient charge transport and temperature responsiveness are critical, particularly in waste-heat recovery systems and optoelectronic technologies. Additionally, they contribute to improved electrical transport and reduced thermal conductivity. Consequently, these findings are pertinent to the design of high-performance thermoelectric materials with enhanced efficiency [95]. Our results underscore the capability of $Li_{3}xLa_{2/3-x}TiO_{3}$ (LLTO with $x = 0.125$) to deliver commendable thermoelectric performance across an extensive temperature range, particularly at elevated temperatures above room temperature [91]. The observed trends align with existing literature regarding complex oxides and advanced structures utilized for thermoelectric conversion, thereby substantiating the potential of LLTO as a viable candidate for industrial heat recovery applications [96,97] or as a power source for autonomous devices [62,72].

## 4. Conclusion

In conclusion, this study demonstrates the extraordinary potential of $Li_{3}xLa_{2/3-x}TiO_{3}$ (LLTO with $x = 0.125$) as a versatile material for high-tech energy-storage and -conversion technologies. By the solid sintering method, LLTO exhibits a structurally stable orthorhombic and a high environmental compatibility, while offering an exceptional dielectric behavior marked by a very high dielectric constant at low frequency and at high temperature, with moderate losses indicating a strong ion conduction typical of ion-conducting perovskites. The impedance and

conductivity studies show a high mobility of $Li^{+}$ ions and a significant increase in electrical conductivity with temperature $10^{-2}$ S/m at 800 °C, with the ion activation energy close to the literature. Thus, LLTO may be used as a solid electrolyte in lithium-ion batteries. Theoretically, DFT simulations demonstrate the structure's stability and an appropriate semi-conductor gap, while the BoltzTraP simulation shows excellent thermoelectric performances, in particular, a high Seebeck coefficient (up to 4.5 µV/K at 500 K) and a ZT figure of merit that increases regularly with temperature, reaching values close to 1 at 500 K. This behavior reveals a potential for the conversion of thermal energy into electric one, which is added to the outstanding ionic transport properties. Ultimately, LLTO exhibits exceptionally high ionic conductivity, along with significant mechanical and thermal stability, commendable thermoelectric performance, and enhanced dielectric properties. These characteristics position it as a preferred material for next-generation energy devices, including solid-state batteries and thermoelectric converters, as evidenced by a considerable body of recent research in the field.

## CRediT authorship contribution statement

**Hicham Kacimi-Naciri:** Writing – review & editing, Writing original draft, Resources, Methodology, Investigation, Formal analysis, Data curation, Conceptualization. **Meriem Ben Zennou:** Writing, Investigation, Resources. **Assia Mabrouk:** Writing – review & editing, Validation, Resources, Methodology, Investigation, Formal analysis, Data curation, Supervision. **Ahmed Bachar:** Writing – review & editing, Validation, Supervision, Methodology, Investigation, Formal analysis. **Amine EL Azizi:** Investigation, Formal analysis, Data curation. **Mohamed Loutou:** Investigation, Formal analysis, Data curation. **Mohammed Mansori:** Validation, Investigation. **Rachid Amrousse:** Validation, Visualization. **Nadia Faska:** Validation, Visualization

## Declaration of competing interest

There are no known financial or personal ties between the authors that may have influenced the study's findings.

## Data Availability

Data will be made accessible upon request.

## References

[1] P. Kokmat, P. Matsayamat, K. Wongrach, P. Surinlert, A. Ruammaitree, Improvement of specific capacity of lithium iron phosphate battery by increasing the surface area and electrical conductivity of cathode electrode using graphene foam, J. Met. Mater. Miner. 33 (2023) 1779, https://doi.org/10.55713/jmmm.v33i4.1779.

[2] X. Chang, G. Liu, M. Wu, M. Chang, X. Zhao, G.Z. Chen, et al., Dual-functional ZnO/LiF layer protected lithium metal for stable $Li_{10}GeP_{2}S_{12}$-based all-solid-state lithium batteries, Battery Energy 2 (2023) 2022051, https://doi.org/10.1002/bte2.2022051.

[3] Zheng N., Zhang C., Lv Y., Cheng L., Yao L., Liu W. Low-temperature Synthesis of Lithium Lanthanum Titanate/Carbon Nanowires for Fast-charging Li-ion Battery n. d.

[4] W. Zhang, Y. Wu, Z. Xu, H. Li, M. Xu, J. Li, et al., Rationally designed sodium chromium vanadium phosphate cathodes with multi-electron reaction for fast-charging sodium-ion batteries, Adv. Energy Mater. 12 (2022) 2201065, https://doi.org/10.1002/aemn.202201065.

[5] P.U. Nzereogu, A. Oyesanya, S.N. Ogba, S.O. Ayanwunmi, M.S. Sobajo, V. C. Chimsunum, et al., Solid-State lithium-ion battery electrolytes: revolutionizing energy density and safety, Hybrid. Adv. 8 (2025) 100339, https://doi.org/10.1016/j.hybadv.2024.100339.

[6] W. Tong, Y. Chen, S. Gong, S. Zhu, J. Tian, J. Qin, et al., Construction of ultrastable and high-rate performance zinc anode with three-dimensional porous structure and Schottky contact, J. Power Sources 591 (2024) 233887, https://doi.org/10.1016/j.jpowsour.2023.233887.

[7] S. Min, X. Liu, A. Wang, F. Ning, Y. Liu, J. Qin, et al., Facile construction of a water-defendable Li anode protection enables rechargeable Li-O2 battery operating in humid atmosphere, Chin. Chem. Lett. 34 (2023) 108586, https://doi.org/10.1016/j.cclet.2023.108586.
[8] W. Arnold, V. Shreyas, Y. Dli, M.K. Koralalage, J.B. Jasinski, A. Thapa, et al., Synthesis of fluorine-doped lithium argyrodite solid electrolytes for solid-state lithium metal batteries, ACS Appl. Mater. Interfaces 14 (2022) 11483-11492, https://doi.org/10.1021/acsmi.1c24468.

[9] B. Helm, N. Minafra, B. Wankmiller, M.T. Agne, C. Li, A. Senyshyn, et al., Correlating structural disorder to Li⁺ ion transport in Li₄-xGe 1-xSb xS₄ (0 ≤ x ≤ 0.2), Chem. Mater. 34 (2022) 5558-5570, https://doi.org/10.1021/acs.chemmater.2c00608.

[10] J. Lau, R.H. DeBlock, D.M. Butts, D.S. Ashby, C.S. Choi, B.S. Dunn, Sulfide solid electrolytes for lithium battery applications, Adv. Energy Mater. 8 (2018) 1800933, https://doi.org/10.1002/aenm.201800933.

[11] Z. Li, J. Fu, X. Zhou, S. Gui, L. Wei, H. Yang, et al., Ionic conduction in polymer-based solid electrolytes, Adv. Sci. 10 (2023) 2201718, https://doi.org/10.1002/advs.202201718.

[12] M. Umair, S. Zhou, W. Li, H.T.H. Rana, J. Yang, L. Cheng, et al., Oxide solid electrolytes in solid-state batteries, Batter. Amp. Supercaps 8 (2025) e202400667, https://doi.org/10.1002/batt.202400667.

[13] S. Yan, H. Al-Salih, C.-H. Yim, A. Merati, E.A. Baranova, A. Weck, et al., Engineered interfaces between perovskite La2/3Li3TiO3 electrolyte and Li metal for solid-state batteries, Front Chem. 10 (2022) 966274, https://doi.org/10.3389/fchem.2022.966274.

[14] Y. Sun, P. Guan, Y. Liu, H. Xu, S. Li, D. Chu, Recent progress in lithium lanthanum titanate electrolyte towards all solid-state lithium ion secondary battery, Crit. Rev. Solid State Mater. Sci. 44 (2019) 265-282, https://doi.org/10.1080/10408436.2018.1485551.

[15] Y. Hu, F. Yang, J. Li, Q. Hu, Lithium Lanthanum Titanate (LLTO) solid electrolyte with high ionic conductivity and excellent mechanical properties prepared by aerodynamic levitation rapid solidification, Crystals 15 (2025) 707, https://doi.org/10.3390/cryst15080707.

[16] J. Lu, Y. Li, Perovskite-type Li-ion solid electrolytes: a review, J. Mater. Sci. Electron 32 (2021) 9736-9754, https://doi.org/10.1007/s10854-021-05699-8.

[17] J.-K. Ahn, S.-G. Yoon, Characteristics of amorphous lithium lanthanum titanate electrolyte thin films grown by PLD for USe in Rechargeable Lithium Microbatteries, Electrochem SolidState Lett. 8 (2005) A75, https://doi.org/10.1149/1.1843571.

[18] F. Tan, H. An, N. Li, J. Du, Z. Peng, A study on Li₀.₃ₐ La₀.₅₅ TiO₃ solid electrolyte with high ionic conductivity and its application in flexible all-solid-state batteries, Nanoscale 13 (2021) 11518-11524, https://doi.org/10.1039/D1N02427B.

[19] T. Teranishi, Y. Ishii, H. Hayashi, A. Kishimoto, Lithium ion conductivity of oriented Li0.33La0.56TiO3 solid electrolyte films prepared by a sol-gel process, Solid State Ion. 284 (2016) 1-6, https://doi.org/10.1016/j.ssi.2015.11.029.

[20] K. Mori, S. Tomihira, K. Iwase, T. Fukunaga, Visualization of conduction pathways in a lanthanum lithium titanate superionic conductor synthesized by rapid cooling, Solid State Ion. 268 (2014) 76-81, https://doi.org/10.1016/j.ssi.2014.09.030.

[21] S. Stramare, V. Thangadurai, W. Weppner, Lithium lanthanum titanates: a review, Chem. Mater. 15 (2003) 3974-3990, https://doi.org/10.1021/cm0300516.

[22] H. Zaitouni, S. Taoussi, L. Ouachouati, S. Benyoussef, D. Mezzane, L. Hajji, et al., Efficient dual-site substitution in perovskite Li0.33La0.557TiO3: a pathway to enhanced electrical conductivity with low activation energy, J. Power Sources 659 (2025) 238416, https://doi.org/10.1016/j.jpwoursour.2025.238416.

[23] A. Okos, C.F. Ciobota, A.M. Motoc, R.-R. Piticescu, Review on synthesis and properties of lithium lanthanum titanate, Materials 16 (2023) 7088, https://doi.org/10.3390/ma16227088.

[24] E. Hatzikraniotis, G. S. Polymeris, T. Kyatzi, Thermal Conductivity in Thermoelectric Materials, in: R. Vargas-Bernal, R. Palma Guerrero (Eds.), Novel Applications of Piezoelectric and Thermoelectric Materials, IntechOpen, 2024, https://doi.org/10.5772/intechopen.10168.

[25] Z. Darhi, S. Malki, H. Abbadi, L. El Farh, I. Guesmi, A. Challioui, Ab-initio calculation of the structural, electronic, mechanical, optical, and thermoelectric properties of orthorhombic ZnAs compound, Physica B Condensed Matter 654 (2023) 414722, https://doi.org/10.1016/j.lphysb.2023.414722.

[26] K. Schwarz, DFT calculations of solids with LAPW and WIEN2k, J. Solid State Chem. 176 (2003) 319-328, https://doi.org/10.1016/S0022-4596(03)00213-5.

[27] P. Blaha, K. Schwarz, F. Tran, R. Laskowski, G.K.H. Madsen, L.D. Marks, WIEN2k: an APW+lo program for calculating the properties of solids, J. Chem. Phys. 152 (2020), https://doi.org/10.1063/1.5143061.

[28] G.K.H. Madsen, D.J. Singh, BoltzTrap. A code for calculating band-structure dependent quantities, Comput. Phys. Commun. 175 (2006) 67-71, https://doi.org/10.1016/j.cpc.2006.03.007.

[29] N.S. Arul, V.D. Nithya, Revolution of Peroxvskite: Synthesis, Properties and Applications, Springer Singapore, Singapore, 2020, https://doi.org/10.1007/978-981-15-1267-4.

[30] B. Antoniassi, A.H.M. González, S.L. Fernandes, C.F.O. Graeff, Microstructural and electrochemical study of La0.5Li0.5TiO3, Mater. Chem. Phys. 127 (2011) 51-55, https://doi.org/10.1016/j.matchemphys.2010.12.021.

[31] W. Koch, M.C.A. Holthausen, Chemist's Guide to Density Functional Theory, First ed, Wiley, 2001, https://doi.org/10.1002/3527600043.

[32] A. Otero-de-la-Roza, V. Luaña, Gibbs2: a new version of the quasi-harmonic model code. I. Robust treatment of the complex data, Comput. Phys. Commun. 182 (2011) 1708-1720, https://doi.org/10.1016/j.cpc.2011.04.016.

[33] J.P. Perdew, K. Burke, M. Ernzerhof, Generalized Gradient Approximation Made Simple, Phys. Rev. Lett. 77 (1996) 3865-3868, https://doi.org/10.1103/PhysRevLett.77.3865.

[34] R.K. Gupta, R. Agarwalla, B.H. Naik, J.R. Evuri, A. Thapa, T.D. Singh, Prediction of research trends using LDA based topic modeling, Glob. Transit. Proc. 3 (2022) 298-304, https://doi.org/10.1016/j.gltp.2022.03.015.

[35] P. Borstnar, J. Zuntar, M. Spreitzer, G. Dražić, N. Daneu, Exaggerated grain growth and the development of coarse-grained microstructures in lithium lanthanum titanate perovskite ceramics, J. Eur. Ceram. Soc. 43 (2023) 1017-1027, https://doi.org/10.1016/j.jeurceramsoc.2022.11.004.

[36] W.L. Tan, C.R. McNeill, X-ray diffraction of photovoltaic perovskites: principles and applications, Appl. Phys. Rev. 9 (2022) 021310, https://doi.org/10.1063/5.0076665.

[37] L. Zhang, X. Zhang, G. Tian, Q. Zhang, M. Knapp, H. Ehrenberg, et al., Lithium lanthanum titanate perovskite as an anode for lithium ion batteries, Nat. Commun. 11 (2020) 3490, https://doi.org/10.1038/s41467-020-17233-1.

[38] D. Wang, Z. Wang, W. Liang, Y. Han, Y. Zhao, Y. Lv, et al., Functional dielectric materials for high-performance solid-state batteries, Mater. Chem. Front 8 (2024) 354-380, https://doi.org/10.1039/D3QM00964E.

[39] M. Samet, A. Kallel, A. Serghei, Maxwell-Wagner-Sillars interfacial polarization in dielectric spectra of composite materials: Scaling laws and applications, J. Compos. Mater. 56 (2022) 3197-3217, https://doi.org/10.1177/00219983221090629.

[40] Z. Liu, L. Qin, X. Cao, J. Zhou, A. Pan, G. Fang, et al., Ion migration and defect effect of electrode materials in multivalent-ion batteries, Prog. Mater. Sci. 125 (2022) 100911, https://doi.org/10.1016/j.pmatsci.2021.100911.

[41] D. Cheng, J. Hong, D. Lee, S.-Y. Lee, H. Zheng, In situ TEM characterization of battery materials, Chem. Rev. 125 (2025) 1840-1896, https://doi.org/10.1021/acs.chemrev.4c00507.

[42] T.S. Kang, M. Morikawa, M. Singh, N. Kimizuka, Electric field-driven long-range order and enhanced polarization switching in high-dipole ionic liquids, J. Am. Chem. Soc. 147 (2025) 8809-8819, https://doi.org/10.1021/jacs.5c00098.

[43] X. Guan, Z. Lei, R. Xue, Z. Li, P. Li, M. David, et al., Polarization: a universal driving force for energy, environment, and electronics, Adv. Mater. 37 (2025) 2413525, https://doi.org/10.1002/adma.202413525.

[44] Y. Lu, J. Gao, X. Ye, S. Guo, M. Shuai, L. Yang, et al., The high temperature dielectric properties and temperature rise behavior of lithium hydride in microwave field, Ceram. Int. 51 (2025) 9939-9946, https://doi.org/10.1016/j.ceramint.2024.12.426.

[45] Y. Zhu, W. Li, L. Zhang, W. Fang, Q. Ruan, J. Li, et al., Electrode/electrolyte interphases in high-temperature batteries: a review, Energy Environ. Sci. 16 (2023) 2825-2855, https://doi.org/10.1039/D3EE00439B.

[46] A.D. Dembitskiy, S.N. Marshenya, E.V. Antipov, S.S. Fedotov, D.A. Aksyonov, A new class of solid electrolytes with an ultra-low Na-ion migration barrier, J. Power Sources 642 (2025) 236979, https://doi.org/10.1016/j.jpwoursour.2025.236979.

[47] Yu.A. Kirsanov, Thermal relaxation and heat conduction of a solid body, J. Eng. Phys. Thermophys. 98 (2025) 256-263, https://doi.org/10.1007/s10891-025-03097-z.

[48] Aradhya R., Madhu B.M., Sundara Rajan J. Low frequency dielectric analysis for understanding water absorption characteristics of epoxy nanocomposites. Polymer Composites n.d.;n/a. https://doi.org/10.1002/pc.29863.

[49] A. Tataroglu, H. Durmus, A.F. Vahid, B. Avar, Ş. Altundal, High-temperature sensitivity complex dielectric/electric modulus, loss tangent, and AC conductivity in Au/(S:DLC)/p-Si (MIS) structures, J. Mater. Sci. Mater. Electron 35 (2024) 227, https://doi.org/10.1007/s10854-024-12007-7.

[50] S. Karmakar, S. Sahoo, H.S. Mohanty, R. Boddhula, G.N. Reddy, S.R. Mohapatra, et al., Unraveling electrical transport and dielectric relaxation in P2-Type NaMg0.25Mn0.75O2: a promising layered oxide for high-temperature electronics, Ceram. Int. (2025), https://doi.org/10.1016/j.ceramint.2025.05.030.

[51] M.U. Fayaz, Q. Wang, S. Liang, H. Bai, F. Pan, C. Song, Electric field induced ion migration and property tuning in functional oxides, Acc. Mater. Res 5 (2024) 648-660, https://doi.org/10.1021/ac accountsr.4c00067.

[52] Y. Lim, Y. Kim, J. Choi, Electro-mechanical factor affecting the Li+/Mg2+ selectivity performance of ion separation metal-organic frameworks, J. Mater. Chem. A 12 (2024) 16657-16666, https://doi.org/10.1039/D4TA02280G.

[53] P. Gao, Z. Chen, Y. Gong, R. Zhang, H. Liu, P. Tang, et al., The Role of Cation Vacancies in Electrode Materials for Enhanced Electrochemical Energy Storage: Synthesis, Advanced Characterization, and Fundamentals, Adv. Energy Mater. 10 (2020) 1903780, https://doi.org/10.1002/aenm.201903780.

[54] A.Yu Sorosov, D.R. Maslennikov, O.G. Kharlanov, I.Yu Chernyshov, V.V. Bruevich, D.Yu Paraschuk, Impact of low-frequency vibrations on charge transport in high-mobility organic semiconductors, Phys. Status Solidi (RRL) Rapid Res. Lett. 13 (2019) 1800485, https://doi.org/10.1002/pssr.201800485.

[55] T. Ahmad, N. Mushtaq, H. Mansha, K. Zaman, M. Khalid, M.A. Masood, et al., Unveiling exceptional conduction mechanism and high proton conductivity in amorphous electrolyte for advanced ceramic fuel cells, Fuel 383 (2025) 133825, https://doi.org/10.1016/j.fuel.2024.133825.

[56] J.A. Dawson, P. Canepa, M.J. Clarke, T. Famprikis, D. Ghosh, M.S. Islam, Toward understanding the different influences of grain boundaries on ion transport in sulfide and oxide solid electrolytes, Chem. Mater. 31 (2019) 5296-5304, https://doi.org/10.1021/acs.chemmater.9b01794.

[57] R. Sarkar, B. Sarkar, S. Pal, Na+ Substitution in GdMnO3 multiferroic oxides: a gateway to enhance structural and dielectric properties, J. Electron Mater. (2025), https://doi.org/10.1007/s11664-025-12016-0.

[58] J.V. Garcia Milério, J.B. da Silva, F.X. Nobre, R.M. Mendonça, M.V. Botelho do Nascimento, E. Antonelli, et al., Tuning ionic conductivity and thermal stability in POMA-Enriched LLZO composites for next-generation lithium-ion batteries, J. Phys. Chem. C. 129 (2025) 9127-9139, https://doi.org/10.1021/acs.jpcc.5c00830.

[59] H. Yang, N. Wu, Ionic conductivity and ion transport mechanisms of solid-state lithium-ion battery electrolytes: a review, Energy Sci. Eng. 10 (2022) 1643-1671, https://doi.org/10.1002/ese3.1163.
[60] R.T. Sibatov, V.V. Svetukhin, E.P. Kitsyuk, A.A. Pavlov, Fractional differential generalization of the single particle model of a lithium-ion cell, Electronics 8 (2019) 650, https://doi.org/10.3399/electronics806056.

[61] C. Gao, X. Zhou, R. Yu, C. Li, X. Gao, W. Yang, et al., Synergistic modulation of grain boundary and domain boundary enhances the ionic conductivity of Li0.33La0.56Ti03 solid electrolyte, ACS Nano 19 (11) (2025) 10902, https://doi.org/10.1021/acsnano.4c15481.

[62] J. Lu, Y. Li, Perovskite-type Li-ion solid electrolytes: a review, J. Mater. Sci. Mater. Electron 32 (2021) 9736-9754, https://doi.org/10.1007/s10854-021-05699-8.

[63] L. Feng, B. Wang, K. Kim, L.F. Wan, B.C. Wood, T.W. Heo, Machine-learning-assisted deciphering of microstructural effects on ionic transport in composite materials: a case study of Li7La3Zr12LiCoO2, Energy Storage Mater. 73 (2024) 103776, https://doi.org/10.1016/j.ensm.2024.103776.

[64] C. Wang, B.B. Xu, X. Zhang, W. Sun, J. Chen, H. Pan, et al., Ion hopping: design principles for strategies to improve ionic conductivity for inorganic solid electrolytes, Small 18 (2022) 2107064, https://doi.org/10.1002/smll.202107064.

[65] Y. Gao, A.M. Nolan, P. Du, Y. Wu, C. Yang, Q. Chen, et al., Classical and emerging characterization techniques for investigation of ion transport mechanisms in crystalline fast ionic conductors, Chem. Rev. 120 (2020) 5954-6008, https://doi.org/10.1021/acs.chemrev.9b00747.

[66] K.M.A. Saron, M. Ouassa, N.K. Hassan, M.G. Moustafa, T. Kallel, A.K. Aladim, et al., Frequency and voltage dependent of electrical and dielectric properties of 14 nm Fully Depleted Silicon-On-Insulator (FD-SOI), Physica B Condensed Matter 704 (2025) 417061, https://doi.org/10.1016/j.physb.2025.417061.

[67] W. Xie, Z. Deng, Z. Liu, T. Famprikis, K.T. Butler, P. Canepa, Effects of grain boundaries and surfaces on electronic and mechanical properties of solid electrolytes, Adv. Energy Mater. 14 (2024) 2304230, https://doi.org/10.1002/aemn.202304230.

[68] W. Li, J. Shi, K.H. L. Zhang, J. L. MacManus-Driscoll, Defects in complex oxide thin films for electronics and energy applications: challenges and opportunities, Mater. Horiz. 7 (2020) 2832-2859, https://doi.org/10.1039/D0MH00899K.

[69] H. Yang, N. Wu, Ionic conductivity and ion transport mechanisms of solid-state lithium-ion battery electrolytes: a review, Energy Sci. Eng. 10 (2022) 1643-1671, https://doi.org/10.1002/ese3.1163.

[70] E.B. Díaz-Cruz, E. Regalado-Pérez, J. Santos-Cruz, J. Alvarado, D. Meneses-Rodríguez, J. Villanueva-Cab, Temperature-Dependent Li+ Diffusion and Its Influence on Doping Profile and Stability of Perovskite Solar Cells, ACS Appl. Energy Mater. 8 (2025) 4331-4344, https://doi.org/10.1021/acsaeam.4c03247.

[71] S. Kainat, J. Anwer, A. Hamid, N. Gull, S.M. Khan, Electrolytes in lithium-ion batteries: advancements in the era of twenties (2020's), Mater. Chem. Phys. 313 (2024) 128796, https://doi.org/10.1016/j.matchemphys.2023.128796.

[72] L. Wang, X.-L. Shi, Y. Yue, L. Li, C. Dong, J. Guan, et al., Advances in solid-state and flexible thermoelectric coolers for battery thermal management systems, Soft Sci. 4 (2024). Article number: 32.

[73] J. Ibarba, Influence of composition on the structure and conductivity of the fast ionic conductors La2/3-xLi3xTiO3 (0.03<x≤0.167), Solid State Ion. 134 (2000) 219-228, https://doi.org/10.1016/S0167-2738(00)00761-X.

[74] M. Schlüter, L.J. Sham, Density-Functional Theory of the Band Gap, in: Löwdin P-O, editor. Advances in Quantum Chemistry, 21, Academic Press, 1990, pp. 97-112, https://doi.org/10.1016/S0065-3276(08)60593-6.

[75] S. Ono, Y. Seki, S. Kashida, M. Kobayashi, Electronic band structure and Li diffusion paths in (La)LiTiO3, Solid State Ion. 177 (2006) 1145-1148, https://doi.org/10.1016/j.ssi.2006.04.030.

[76] E.E. Jay, M.J.D. Rushton, A. Chroneos, R.W. Grimes, J.A. Kilner, Genetics of superionic conductivity in lithium lanthanum titanates, Phys. Chem. Chem. Phys. 17 (2015) 178-183, https://doi.org/10.1039/C4CP04834B.

[77] M. Catti, First-Principles Modeling of Lithium Ordering in the LLTO (Li x La2/3-x TiO3) Superionic Conductor, Chem. Mater. 19 (2007) 3963-3972, https://doi.org/10.1021/cm0709469.

[78] L. Zhang, X. Zhang, G. Tian, Q. Zhang, M. Knapp, H. Ehrenberg, et al., Lithium lanthanum titanate perovskite as an anode for lithium ion batteries, Nat. Commun. 11 (2020) 3490, https://doi.org/10.1038/s41467-020-17233-1.

[79] S. Abu Alrub, M.S. Khan, Comprehensive study of the light-matter interactions, thermoelectric properties, and elastic features of quaternary materials, Opt. Mater. Express 15 (2025) 2552, https://doi.org/10.1364/OME.573767.

[80] S.A.R. Alharbi, B. Gul, M.S. Khan, S.M. Aziz, Li-based ternary semiconductors: probing electronic, mechanical, optical, and transport nature from first principles study, Micro Nanostruct. 208 (2025) 208357, https://doi.org/10.1016/j.micrna.2025.208357.

[81] M. Al-Hmoud, B. Gul, M.S. Khan, S.M. Aziz, The optoelectronic and thermoelectric properties of PrTi2InX4 (X = Se, Te) chalcogenides: for energy harvesting applications, Inorg. Chem. Commun. 182 (2025) 115406, https://doi.org/10.1016/j.inoche.2025.115406.

[82] H.J. Goldsmid, Introduction to Thermoelectricity, 121, Springer Berlin Heidelberg, Berlin, Heidelberg, 2016, https://doi.org/10.1007/978-3-662-49256-7.

[83] Boy J., Handwerg M., Ahrling R., Mitdank R., Wagner G., Galazka Z., et al., Temperature dependence of the Seebeck coefficient of epitaxial Sβ-SaGα_2SβS_3 thin films 2018. https://doi.org/10.48550/ARXIV.1812.02408.

[84] B. Gul, S.A.R. Alharbi, M.S. Khan, S.M. Aziz, Substitutional impact of alkali metals on the electronic structure, optical, mechanical, and transport properties of novel ternary materials, Micro Nanostruct. 208 (2025) 208374, https://doi.org/10.1016/j.micrna.2025.208374.

[85] B. Gul, N. Madkhali, M.S. Khan, G. Khan, S.M. Aziz, S. Alanazi, et al., Exploring Al- and Ga-based quaternary materials: toward next-gen UV protection and solar efficiency, Solid State Sci. 169 (2025) 108092, https://doi.org/10.1016/j solidstatesciences.2025.108092.

[86] A.S. Mohamed, B. Gul, M.S. Khan, G. Benabdellah, S.M. Aziz, F. Abbas, Systematic exploration of electronic, optical, and thermoelectric properties of SrCuXF (X = S, Se) materials: employing first-principles calculations, Braz. J. Phys. 55 (2025) 224, https://doi.org/10.1007/s13538-025-01853-3.

[87] D.J. Sánchez-Trujillo, L.V. Osorio-Maldonado, J.J. Prías-Barragán, Temperature dependence of electrical conductivity and variable hopping range mechanism on graphene oxide films, Sci. Rep. 13 (2023) 4810, https://doi.org/10.1038/s41598-023-31778-3.

[88] P. Nayak, D.C. Gupta, First-principles calculations to investigate thermoelectric, thermophysical, and optical properties of RNi4P12 (R = Sm, Eu) rare-earth metal skutterudites, Sci. Rep. 14 (2024) 31581, https://doi.org/10.1038/s41598-024-76538-z.

[89] O. Chouikhi, R. Masrou, Study of structural, electronic, thermodynamic, thermoelectric, and optical properties of superconductor spinel LiTi2O4: An ab initio calculations, J. Power Sources 634 (2025) 236453, https://doi.org/10.1016/j.jpowsour.2025.236453.

[90] H.S. Patel, V.A. Dabhi, A.M. Vora, Advanced study of the electronic and thermoelectric properties of AEMSe compounds under compression and tensile strain, Mater. Adv. 6 (2025) 5777-5791, https://doi.org/10.1039/D5MA00297D.

[91] J. Wang, N. Wu, P. Bai, Temperature-dependent Li-ion transport in lithium lanthanum titanate electrolytes, Chem. Commun. 60 (2024) 8844-8847, https://doi.org/10.1039/D4CC02120G.

[92] T. Lan, B. Song, J. Xu, N. Xin, Z. Li, M. He, et al., The experimental study on the thermoelectric properties of sputtered amorphous molybdenum disulfide films, Nanoscale Microsc. Thermophys. Eng. 29 (2025) 79-95, https://doi.org/10.1080/15567265.2025.2458865.

[93] S. Stramare, V. Thangadurai, W. Weppner, Lithium lanthanum titanates: a review, Chem. Mater. 15 (2003) 3974-3990, https://doi.org/10.1021/cm0300516.

[94] B. Gul, M.M.A. Al-Hmoud, M.S. Khan, S.M. Aziz, Exploring the potential of TiInX2 (X = Se, Te) materials: First-principles investigation for the optoelectronic and thermoelectric applications, Chem. Phys. Lett. 869 (2025) 142069, https://doi.org/10.1016/j.cplett.2025.142069.

[95] P.S. De, S.S. Vadlamani, S. Vedantam, Parametric study on the role of energy and mobility on abnormal grain growth in systems undergoing complexion transition, Model. Simul. Mater. Sci. Eng. 33 (2025) 025010, https://doi.org/10.1088/1361-651X/ada81a.

[96] J. Lu, Y. Li, Perovskite-type Li-ion solid electrolytes: a review, J. Mater. Sci. Mater. Electron 32 (2021) 9736-9754, https://doi.org/10.1007/s10854-021-05699-8.

[97] L. Lv, X. Zhang, J. Wang, L. Yuan, J. Fan, Construction of Li0.5La0.5TiO3 (LLTO)-In2O3 n-n step scheme heterostructure nanorods for drastically heightening the sensing behavior in H2S gas, Mater. Chem. Phys. 295 (2023) 127085, https://doi.org/10.1016/j.matchemphys.2022.127085.