As one of the highest-capacity commercial cathodes, lithium-rich manganese oxide (LMNO) currently faces challenges related to suboptimal structural stability and capacity retention. We find that this challenge is attributed to internal stress caused by limited grain growth and inherent lattice strain within LMNO. A simple and effective heat treatment strategy, combining Zr doping, is proposed to address these issues. Zr doping increases lattice spacing, alleviating the inherent lattice strain in the two-phase region. Thermal shock promotes atomic diffusion and grain boundary migration, reducing the number of grain boundaries and phase interfaces, thereby alleviating internal stress and facilitating grain growth. Finally, this design with reduced internal stress results in superior structural stability and cycle retention. After 200 cycles at 0.5C current density, the capacity retention of LMNO reaches 93.02%, with significantly suppressed voltage decay. This work underscores the importance of internal stress management in achieving highly stable cathode materials, offering new insights for the design and optimization of cathode materials.

Low-temperature sintering of PIN-PHT piezoceramics is severely restricted by the trade-off between sintering temperature reduction and property degradation, where single additives commonly induce amorphous grain-boundary phases and impair piezoelectric performance. Herein, a Li2CO3-CuO-Bi2O3 (LBC) composite additive is proposed to break this bottleneck, enabling solid-state densification at 1025 ℃, dominated by grain-boundary diffusion, with glass-free grain boundaries as the resulting microstructural feature and simultaneous enhancement of piezoelectricity and thermal stability. The LBC dopants are inferred to enter the perovskite A/B sites controllably, generating oxygen vacancies and likely forming defect dipoles such as (Li′PbV″O), which are expected to reduce the grain-boundary diffusion activation energy based on classical defect chemistry of acceptor-doped perovskites. Clean crystalline grain boundaries facilitate rapid mass transport, while optimized tetragonal distortion and multiscale domain structure synergistically lower domain-switching barriers and strengthen relaxor behavior. The optimized PIN-PHT-0.8LBC ceramic achieves superior properties: d33 = 603 ± 16 pC/N, εᵣ = 2846 ± 30, TC = 310 ± 3.4 ℃, and 84.2 ± 2.2% piezoelectric retention at 300 ℃, with an ultralow dielectric loss (tanδ) of 0.0031. This work establishes a defect-domain-sintering synergistic mechanism and provides a robust route for low-temperature cofiring of high-performance high-temperature piezoelectric ceramics.

Understanding the intrinsic coupling between polar nanoregions (PNRs) and morphotropic phase boundary (MPB) stability is essential for advancing relaxor-ferroelectric ceramics, yet their mutual interaction remains insufficiently clarified. In this work, the (0.69-x) Pb(Ni1/3Nb2/3)O3-xPb(Lu1/2Nb1/2)O3-0.31PbTiO3 system was designed to modulate local structural disorder and phase competition by incorporating Pb(Lu1/2Nb1/2)O3 (PLN). Systematic investigations of crystal structure, dielectric relaxation, domain configuration, and field-induced phase behavior reveal that PLN alters both the energy landscape and the temperature-dependent evolution of PNRs, thereby influencing MPB stability. Rietveld refinements and temperature-dependent dielectric analyses show that increasing PLN content strengthens the diffuseness and enhances the freezing behavior of PNRs, which shifts the balance between rhombohedral and tetragonal phases and promotes a more dynamic relaxorferroelectric transition. The refined composition-temperature phase diagram further indicates that PNR dynamics are strongly correlated with the flattening of the free-energy profile near the MPB, influencing the reversibility of field-induced transformations. The optimized composition, 0.48PNN-0.21PLN-0.31 PT, exhibits both enhanced electromechanical properties (d33 = 738 pC/N, d33* = 982 p.m./V) and improved thermal stability. These results provide mechanistic insight into how local structural heterogeneity and PNR evolution jointly regulate MPB-related phase equilibria, offering a thermodynamic basis for designing high-performance relaxor ferroelectrics.

Li dendrites are the main obstacle to the practical application of Li metal anodes. Although the solid electrolyte interphase (SEI) is essential for stabilizing Li metal anodes, its formation proceeds concurrently with Li deposition. Therefore, SEI evolution and Li growth are dynamically coupled, yet the underlying mechanism governing this interaction remains unclear. In this study, a competitive reaction mechanism between SEI formation and Li deposition is revealed. A phase-field model was employed at the mesoscopic level to elucidate the effects of Li deposition reaction rates and SEI microstructural integrity. At the macroscopic level, electrochemical impedance spectroscopy (EIS) demonstrated that rapid Li deposition outpaces SEI reconstruction at high current densities, causing severe interfacial rupture. Conversely, rapid SEI kinetics enable fast interfacial repair. Furthermore, the introduction of a competitive reaction mechanism framework (CRMF) advances this dynamic equilibrium from a qualitative concept to a computable metric. Molecular-level analysis then shows that optimizing the structure and kinetic behavior of Li+ solvation can promote anion reduction and lower the desolvation energy barrier. This encourages more anions and solvents to participate in interfacial reactions, accelerating the formation of a stable SEI film. These findings provide valuable insights into developing a stable electrolyte-anode interface in Li metal batteries.

Reversible domain switching is a common method for enhancing piezoelectric response. However, low-energybarrier domain switching simultaneously exacerbates temperature-sensitive phase transitions. This establishes an inverse correlation between "high piezoelectricity and low TC" in conventional systems. It is imperative to break the inherent compromise between piezoelectric response and thermal stability in lead-based ceramics. This study presents a breakthrough in addressing this longstanding issue via atomic-level lattice engineering in Pb(Yb,Nb) O3-Pb(Hf,Ti)O3 systems. A comprehensive investigation, combining advanced characterization techniques and density functional theory (DFT) calculations, elucidates the atomic-scale mechanisms underlying the performance enhancement. The co-doping strategy generates localized heterogeneous regions, primarily manifested distortions at oxygen octahedral sites, which effectively lower the crystal symmetry and facilitate enhanced polarization switching. Our approach achieved a piezoelectric coefficient reaching 592 pC/N in the ceramic, while maintaining excellent thermal characteristics (Curie temperature of 343.1 degrees C) and a dielectric loss (Tan delta) of 0.0121. Compared with the benchmark material (daa = 458 pC/N, Tc = 351.8 degrees C), PYN-PHT-0.8(Li++Mo6+) represents a 30 % enhancement in daa and only a 2.5 % decrease (8.7 degrees C shift) in Tc. Through precise control of local Landau potential energy landscapes at dopant sites, the material demonstrates exceptional thermal stability, maintaining a small fluctuation range (triangle d33 - 4.7 %) across a broad temperature range (ambient temperature-300 degrees C). The findings provide critical insights into providing crucial guidance for designing advanced piezoelectric materials with comprehensive performance.

The pursuit of high-performance energy storage (ES) materials has placed (Bi0.5Na0.5)TiO3 (BNT)-based ceramics at the forefront of research, owing to their exceptional dielectric properties and environmentally friendly composition. This study explores the synergistic enhancement of ES performance in BNT-based ceramics achieved through A-site co-doping with Ca2+, Sr2+, and Ba2+ ions. By integrating electrical testing with thermodynamic analysis, we unveil the mechanisms by which ion doping influences the electrical properties, ES parameters, and free energy of these materials. Our findings reveal that the co-doping strategy significantly widens the band gap and reduces the free energy of BNT-based ceramics, leading to remarkable improvements in recoverable energy density (Wrec) and energy storage efficiency (eta). Additionally, the application of the viscous polymer process (VPP) enhances grain refinement, densification, and dielectric breakdown strength, culminating in the development of 0.4BNT-0.6(Ba0.15Sr0.55Ca0.3)TiO3 (VPP) ceramics with an ultrahigh Wrec of 7.34 J/cm3 and eta of 84.4% at 540 kV/cm. These samples are noteworthy for their remarkable thermal stability, which allows them to sustain steady ES performance across a wide operating temperature range of 20-140 degrees C. This work demonstrates the transformative potential of multi-doping strategies and advanced processing techniques in tailoring the properties of BNT-based ceramics. The insights presented here provide a robust framework for the design of next-generation lead-free ES materials, offering a promising pathway for sustainable ES applications.

High-performance piezoelectric ceramics with excellent thermal stability are essential for actuators and sensors functioning in extreme environments, such as aerospace systems and energy exploration platforms. In this study, a series of Pb(Zr0.5Ti0.5)0.7(Zn1/3Nb2/3)0.3O3-based ceramics, denoted as xCe-0.3PZN-PZT (x = 1-4 mol%), were synthesized via a conventional solid-state reaction route. Among these, the composition with 2 mol% Ce exhibited the most promising electromechanical performance, achieving a large electric-field-induced strain of 0.178 % and a converse piezoelectric coefficient (d & lowast;33) of 590 pm/V under an applied field of 30 kV/cm, along with a low strain hysteresis of 10.4 %. In-situ high-temperature characterizations demonstrated a room-temperature piezoelectric coefficient (d33) value of 467 pC/N and a high electromechanical coupling factor of 65.4 %. Importantly, the d33 value exhibited minimal fluctuation, remaining within +/- 10 % of its initial magnitude over a wide temperature range from 30 degrees C to 230 degrees C. Structural analyses based on X-ray diffraction and piezoresponse force microscopy revealed that Ce doping induces nanoscale structural heterogeneity, which enhances domain wall mobility and contributes to the observed performance. These results offer a compelling strategy for designing thermally robust, high-performance lead-based piezoceramics suitable for deployment in demanding application environments.

Li-based rechargeable batteries have played a critical role in the sustainable energy development strategy. However, the uncontrolled Li dendrites growth, which causes the poor cycling performance and safety concerns, has become their main drawback. Due to the sealed environment of the battery and the active reactivity of Li metal, in situ studies of Li dendrites are challenging. This work presents a trans-scale simulation method for modeling the Li dendrite growth process in Li-based batteries. First, a 2D Li metal battery model (2D LBM) was established to simulate Li nucleation sites at the nanoscale. Then, based on the growth process of nucleation sites in the 2D LBM, a phase-field model was established to simulate the Li dendrite growth process at the macroscopic scale. Furthermore, an in-situ observation experiment of the Li dendrite growth process was performed to illustrate the rationality of the simulation. This study shows the dynamic evolution of the micro-parameters inside the battery and reveals a snowball effect during the Li dendrite growth processes. This work provides a new perspective on understanding the mechanism of Li dendrite growth.

Lead-free antiferroelectric (AFE) ceramics based on sodium niobate (NaNbO3, NN) have garnered interest owing to their outstanding capacity for energy storage. Nevertheless, the utilization of pure NN ceramics is restricted due to their high loss energy density (Wloss) and low breakdown electric field (Eb), which result from the field-induced AFE-ferroelectric (FE) phase transition. To address these issues, Bi and Ta were introduced into the A and B sites of the NN ceramic perovskite structure, respectively. This could change the crystal structure and electronic structure of NaNbO₃, consequently boosting the material’s energy storage performance. After that, Ta elements were embedded in the B-sites of (Na0.86Bi0.14)(Nb0.9Ti0.1)O3 powder, and (Na0.86Bi0.14)(Nb0.9−xTaxTi0.1)O3 ceramics were subsequently produced via traditional solid-phase reaction method. According to the XRD analysis, the compositional modification enabled the fabrication of ceramics with a typical perovskite structure and excellent energy storage performance. At x = 0.15, the relaxation degree reached the maximum, and the relaxation factor γ attained 1.8850. the (Na0.86Bi0.14)(Nb0.75Ta0.15Ti0.1)O3 exhibits favorable temperature stability in the range of 25–125 °C. In particular, the (Na0.86Bi0.14)(Nb0.75Ta0.15Ti0.1)O3 ceramic exhibited an energy capacity density Wrec of about 2.41 J·cm−3 and an efficiency η of about 90.88

Nickel-rich cobalt-free cathode materials have received widespread attention due to their advantages of high energy density, low-cost, and environmental friendliness. However, the instability of the structure and surface interface accelerates the capacity degradation of these materials during cycling. Here, we synthesized LiNi0.9Mn0.1O2 (NM91) nickel-rich cobalt-free cathode material by sol–gel method and optimized it by Zr doping to enhance the electrochemical performance. Comprehensive structural characterization confirmed that Zr doping effectively suppressed the volume change and microcrack formation during the H2–H3 phase transition, reduced the side reactions occurring on the surface, and generated a thinner and more stable CEI layer, which effectively prevented the erosion of the electrolyte. As a result, Zr–NM exhibits superior cycling stability and rate performance. Notably, 0.75

The sintering temperature of piezoelectric ceramics plays a pivotal role in their cost and efficacy within the realm of multilayer actuator applications. While being conducive to piezoelectric capabilities of ceramics, the increase in sintering temperature entails higher fabrication costs. In contrast, a lower sintering temperature can reduce costs, but the performance of the actuator may be compromised. To address these issues, the Li-Sc co-doped 0.46PNN-0.23PIN-0.31 PT ceramics were produced in the present work. At a relatively low sintering temperature (950 degrees C), the synergy of multiple ferroelectric phases and defect polarization could be achieved, thereby augmenting the electromechanical properties of the material. At an optimal doping ratio of 0.6 mol% for both Li and Sc, the ceramics demonstrated superior performance metrics, including d33 = 1000 pC/N, d33* = 1050 p.m./V, kp = 0.53, and epsilon r = 8001. Applying the Rietveld refinement and Rayleigh analysis, it was established that the incorporation of Li is essential in the formation of a rhombohedral phase-dominated morphotropic phase boundary (MPB), which decreases polarization anisotropy amidst the coexisting phases, facilitating polarization rotation and significantly enhancing the piezoelectric properties of ceramics. The nanodomains within the material were detected through SS-PFM and PFM testing. Notably, Sc3+-induced defects disrupted the extended ferroelectric domains, fostering the emergence of nanodomains with higher activity, which in turn enabled to markedly improve the electromechanical performance of the ceramics even at the lower sintering temperature. This investigation not only provides a viable strategy for curtailing the manufacturing costs of multilayer actuators but also opens up new prospects for the low-temperature fabrication of piezoelectric materials and their applications.

This study aims to enhance the energy-storage (ES) performance of lead-free (Bi0.5Na0.5)TiO3 (BNT)-based ceramics by incorporating Bi(Mg0.5Zr0.5)O-3 (BMZ) into the (Bi0.5Na0.4K0.1)TiO3 (BNKT) matrix. The introduction of Mg2+ and Zr4+ ions disrupts the long-range ferroelectric order, significantly improving the material's relaxor ferroelectric characteristics. Notably, this doping strategy does not shift the dielectric anomaly peak, allowing precise control of the permittivity at expected temperature region. The optimized composition, 0.90(0.7BNKT-0.3SrTiO(3))-0.10BMZ, achieves an impressive ES efficiency of 91.3 % and a high recoverable ES density of 6.46 J/cm(3), marking a major advancement in lead-free ES dielectric ceramics. Moreover, the material shows remarkable stability within a broad range of temperatures (20-140 degrees C) and frequencies (1-100 Hz), indicating strong ES performance for practical uses. These results highlight the significant potential of this material for high-efficiency ES applications and lay the groundwork for future developments in lead-free ES dielectric ceramics.

Lead-free (Bi0.5Na0.5)TiO3 (BNT)-based ceramics play a vital role in transducers and sensors, owing to their pronounced electrostrain response under applied electric fields. This work presents a notable electrostrain response of 0.54 % with minimal electrostrain hysteresis (11 %) in the x = 0.30 composition near the morphotropic phase boundary (MPB) within (1-x)BNT-x(Ba0.15Sr0.55Ca0.3)TiO3 (x = 0.2-0.4, BNT-xBSCT) ceramics. By exploiting the variation in tolerance factor through titanate doping and localized disorder from A-site multiple ion substitution, we achieved enhanced electrostrain response via the evolution of nonergodic relaxor (NR) and ergodic relaxor (ER) phase boundaries. Notably, the x = 0.30 composition exhibits ultrahigh electrostrain (>0.5 %) with remarkable thermal stability above 70 degrees C. This stability arises from the combined effects of domain flipping in ER/NR mixed phases and reversible electric field-induced relaxor-to-ferroelectric phase transitions. These results hold significant potential for advancing electrostrain performance and thermal stability in lead-free BNT-based ceramics.

Lithium dendrites are widely acknowledged as the main culprit of the degradation of performance in various Li-based batteries. Studying the mechanism of lithium dendrite formation is challenging because of the high reactivity of lithium metal. In this work, a phase field model and in situ observation experiments were used to study the growth kinetics and morphologies of lithium dendrites in terms of anisotropy, temperature, and potential difference. Subsequently, a 2D numerical simulation has been developed to illustrate the impact of microscopic parameters, such as electrolyte potential, current distribution, and anode overpotential, on the growth of lithium dendrites after nucleation. Meanwhile, the influence of electrode interface, charging rate, and charging mode on lithium dendrites was also studied using the 2D model and in situ experiments. This work provides comprehensive insights into the kinetics of dendrite formation and morphologies, offering an important theoretical reference for the safety and long-life applications of batteries.

The lead-based perovskite structural piezoelectric ceramics have both rhombohedral and tetragonal phase structures. In order to investigate the difference between these two phase structures, the rhombohedral and tetragonal phase ceramics with 0.11 Pb(In1/2Nb1/2)O3-0.89 Pb(Hf0.47Ti0.53)O3-x mol%Nb2O5 (PIN-PHT-xNb) compositions were prepared in this work via solid-phase reaction method under different sintering conditions. By investigating the bond angles and B-O bond lengths within the oxygen octahedra, the most essential differences between the two phases were revealed from the perspective of crystal structure. In particular, the rhombohedral phase exhibited more complex lattice distortions than the tetragonal phase, which led to the variations in free energy density distributions and free energy barrier heights. Consequently, the ferroelectric domains in the two phases displayed distinct morphologies. For instance, the rhombohedral phase PIN-PHT-1.5Nb (d33 = 490 pC/N, TC = 314.1 degrees C, Pr = 49.21 mu C/cm2) exhibited significant differences in piezoelectric, dielectric and ferroelectric properties along with the temperature stability compared to the tetragonal phase PIN-PHT-0.8Nb (d33 = 764 pC/ N, TC = 319.1 degrees C, Pr = 53.9 mu C/cm2). It was mainly due to the lattice distortion complexity and the presence of large-sized ferroelectric domains in the former phase.

Accurate real-time assessment of the state of health (SOH) of lithium-ion batteries is critical for ensuring their safe operation. Owing to its non-destructive nature, rapid response, and abundant electrochemical information provided, electrochemical impedance spectroscopy (EIS) has become a well-established technique for SOH estimation. Hence, the core challenge is to extract potential health indicators (HIs) from EIS data in order to establish robust SOH mapping models. This review initially introduces SOH definitions and the fundamental principles of EIS; then, it comprehensively surveys the research progress made in EIS-based approaches for HIs extraction, including raw data, equivalent circuit model (ECM), distribution of relaxation times (DRT), and automatic unsupervised identification (AUI) analyses. Crucially, this work summarizes the technical routes connecting HIs extraction methods to SOH estimation and provides the first systematic comparison of AUI and conventional techniques. These approaches leverage advanced empirical models and artificial intelligence to effectively identify and quantify key HIs of performance degradation. Furthermore, the advantages and limitations of these approaches are introduced, analyzed, and compared. Finally, the outlook and challenges for enhancing the SOH estimation are discussed from three perspectives: mechanisms, measurements, and applications. Overall, this review provides a theoretical framework and a technical route for advancing EIS-based SOH estimation, while outlining a future roadmap for non-destructive evaluation technologies, measurement devices, and battery pack-level SOH monitoring.

Co-free and Ni-rich layered cathode materials for lithium-ion batteries have attracted significant attention due to their high capacity and low cost. Existing research has mainly focused on the impact of lattice oxygen (Oo) and oxygen vacancies (Ov) during the charging and discharging processes on the electrochemical performance. However, the influence of intrinsic Oo and Ov on the electrochemical performance of Co-free and Ni-rich cathodes remains to be investigated. In this work, LiNi0.95Mn0.05O2 (NM95) cathodes with different Oo contents were prepared, and their effect on electrochemical performance was studied. The results demonstrate that an optimal Oo content enhances the structural ordering of NM95 and improves Li+ diffusion kinetics. This dual optimization reduces parasitic capacitance effects, ultimately boosting the practical capacity of NM95. At the optimum Oo content, high capacity and rate performance are achieved, with discharge capacities of 208.6 mA h g-1 (2.7-4.3 V) and 222.5 mA h g-1 (2.7-4.5 V) at 1 C. At 5 C and 10 C (2.7-4.3 V), the capacities are 171.6 mA h g-1 and 129.4 mA h g-1, respectively. The Ov content influences the TM-O bonds, Li+ diffusion channels, Oo content at high voltage, and cycling stability of the NM95 cathode. At the optimum Ov content, NM95 exhibits excellent cycle stability, with retention rates of 87.1% and 84.3% after 100 cycles at 2.7-4.3 V and 2.7-4.5 V, respectively. Therefore, controlling the Oo content is an effective and feasible approach to enhancing the capacity and cycle stability of Co-free and Ni-rich cathodes.