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Abstract Solid state lithium metal batteries using garnet solid electrolytes such as LLZTO (Li_6.4La₃Zr_1.5Ta_0.5O₁₂) promise substantial improvements in energy density and safety. However, practical implementation is hindered by lithium dendrite penetration at high current densities. Recent work shows that internal electrochemically induced mechanical stresses are large enough to propagate lithium dendrites and subsequently fracture solid electrolytes. This study builds on this understanding and demonstrates that stress‐driven dendrite propagation can be controlled via deflection at weakly bonded internal interfaces. This approach, based on a fracture‐mechanics analysis of multilayered composites, is investigated with a variety of interlayer materials that are embedded into LLZTO. The viability and effectiveness of dendrite deflection are most clearly evident with reduced graphene oxide where the critical current density increased from 0.6 to 3.8 mA cm⁻². In this material, both the weak interface with LLZTO and the mixed ionic–electronic conducting nature of the interlayer appear to contribute to the improved performance. Additional insight into the mechanics of multilayered electrolytes is also obtained with finite element modeling. The overall results present a promising proof‐of‐concept demonstration along with important generalized design guidelines for creating multilayered solid electrolyte architectures that can enable high‐performance solid‐state batteries. 

Abstract Dendrite growth is one of the leading factors that cause cycling deterioration for all‐solid‐state batteries (ASSBs). However, using a single dominant material to form the solid electrolyte has encountered several setbacks due to the intrinsically competing factors in mechanics and electrochemistry. Inspired by the “brick‐and‐mortar” structure, a strategy of embedding heterogeneous blocks (HBs) within the solid electrolyte (SE) is proposed to mitigate and suppress dendrite growth‐induced internal short circuits (ISCs). A phase‐field‐based multiphysics model is established to describe the dendrite growth behavior. Results reveal that the characteristic length ratioebetween the HBs and SE is the governing factor that dominates the dendrite growth path. The results show that a single long HB and multiple HBs in medium length with specific layouts can suppress and divert dendrite growth and avoid ISCs completely. For short HB cases, HBs can delay the ISC to a certain extent. The results imply that adding an appropriately designed heterogeneous layer into the SE will effectively block dendrites, and also define desired mechanical property domains. This work provides a multiphysics mechanistic understanding of the dendrite growth and SE cracking and opens new perspectives for the material selection and structural design of SEs for long lifecycle ASSBs. 

Abstract With the increasing use of Li batteries for storage, their safety issues and energy densities are attracting considerable attention. Recently, replacing liquid organic electrolytes with solid‐state electrolytes (SSE) has been hailed as the key to developing safe and high‐energy‐density Li batteries. In particular, Li_1+xAl_xTi_2−x(PO4)₃(LATP) has been identified as a very attractive SSE for Li batteries due to its excellent electrochemical stability, low production costs, and good chemical compatibility. However, interfacial reactions with electrodes and poor thermal stability at high temperatures severely restrict the practical use of LATP in solid‐state batteries (SSB). Herein, a systematic review of recent advances in LATP for SSBs is provided. This review starts with a brief introduction to the development history of LATP and then summarizes its structure, ion transport mechanism, and synthesis methods. Challenges (e.g., intrinsic brittleness, interfacial resistance, and compatibility) and corresponding solutions (ionic substitution, additives, protective layers, composite electrolytes, etc.) that are critical for practical applications are then discussed. Last, an outlook on the future research direction of LATP‐based SSB is provided. 

Abstract The presence of the top electrode on hafnium oxide‐based thin films during processing has been shown to drive an increase in the amount of metastable ferroelectric orthorhombic phase and polarization performance. This “Clamping Effect,” also referred to as the Capping or Confinement Effect, is attributed to the mechanical stress and confinement from the top electrode layer. However, other contributions to orthorhombic phase stabilization have been experimentally reported, which may also be affected by the presence of a top electrode. In this study, it is shown that the presence of the top electrode during thermal processing results in larger tensile biaxial stress magnitudes and concomitant increases in ferroelectric phase fraction and polarization response, whereas film chemistry, microstructure, and crystallization temperature are not affected. Through etching experiments and measurement of stress evolution for each processing step, it is shown that the top electrode locally inhibits out‐of‐plane expansion in the HZO during crystallization, which prevents equilibrium monoclinic phase formation and stabilizes the orthorhombic phase. This study provides a mechanistic understanding of the clamping effect and orthorhombic phase formation in ferroelectric hafnium oxide‐based thin films, which informs the future design of these materials to maximize ferroelectric phase purity and corresponding polarization behavior. 

Abstract Two key interfaces in flexible perovskite solar cells (f‐PSCs) are mechanically reinforced simultaneously: one between the electron‐transport layer (ETL) and the 3D metal‐halide perovskite (MHP) thin film using self‐assembled monolayer (SAM), and the other between the 3D‐MHP thin film and the hole‐transport layer (HTL) using an in situ grown low‐dimensional (LD) MHP capping layer. The interfacial mechanical properties are measured and modeled. This rational interface engineering results in the enhancement of not only the mechanical properties of both interfaces but also their optoelectronic properties holistically. As a result, the new class of dual‐interface‐reinforced f‐PSCs has an unprecedented combination of the following three important performance parameters: high power‐conversion efficiency (PCE) of 21.03% (with reduced hysteresis), improved operational stability of 1000 hT₉₀(duration at 90% initial PCE retained), and enhanced mechanical reliability of 10 000 cyclesn₈₈(number of bending cycles at 88% initial PCE retained). The scientific underpinnings of these synergistic enhancements are elucidated.