How Does Stacking Pressure Affect the Performance of Solid Electrolytes and All-Solid-State Lithium Metal Batteries?

All-solid-state lithium metal batteries(ASSLMBs)with solid electrolytes(SEs)have emerged as a promising alternative to liquid electrolyte-based Li-ion batteries due to their higher energy density and safety.However,since ASSLMBs lack the wetting properties of liquid electrolytes,they require stacking pressure to prevent contact loss between electrodes and SEs.Though previous studies showed that stacking pressure could impact certain performance aspects,a comprehensive investigation into the effects of stacking pressure has not been conducted.To address this gap,we utilized the Li_(6)PS_(5)Cl solid electrolyte as a reference and investigated the effects of stacking pressures on the performance of SEs and ASSLMBs.We also developed models to explain the underlying origin of these effects and predict battery performance,such as ionic conductivity and critical current density.Our results demonstrated that an appropriate stacking pressure is necessary to achieve optimal performance,and each step of applying pressure requires a specific pressure value.These findings can help explain discrepancies in the literature and provide guidance to establish standardized testing conditions and reporting benchmarks for ASSLMBs.Overall,this study contributes to the understanding of the impact of stacking pressure on the performance of ASSLMBs and highlights the importance of careful pressure optimization for optimal battery performance.

Predicting air pressure in drainage stack of high-rise building

It is necessary to understand the features of air pressure in a drainage stack of a high-rise building for properly designing and operating a drainage system. This paper presents a mathematical model for predicting the stack performance. A step function is used to describe the effect of the air entrainment caused by the water discharged from branch pipes. An additional source term is introduced to reflect the gas-liquid interphase interaction （GLII） and stack base effect. The drainage stack is divided into upper and base parts. The air pressure in the upper part is predicted by a total variation diminishing （TVD） scheme, while in the base part, it is predicted by a characteristic line method （CLM）. The predicted results are compared with the data measured in a real-scale high- rise test building. It is found that the additional source term in the present model is effective. It intensively influences the air pressure distribution in the stack. The air pressure is also sensitive to the velocity-adjusting parameter （VAP）, the branch pipe air entrainment, and the conditions on the stack bottom.

Fabrication pressures and stack pressures in solid-state battery

Solid-state batteries(SSBs)have received widespread attention with their high safety and high energy density characteristics.However,solid-solid contacts in the internal electrode material and the electrode material/solid electrolyte(SE)interfaces,as well as the severe electrochemo-mechanical effects caused by the internal stress due to the volume change of the active material,these problems hinder ion/electron transport within the SSBs,which significantly deteriorates the electrochemical performance.Applying fabrication pressures and stack pressures are effective measures to improve solid-solid contact and solve electrochemo-mechanical problems.Herein,the influences of different pressures on cathode material,anode material,SEs,and electrode/SEs interface are briefly summarized from the perspective of interface ion diffusion,transmission of electrons and ions in internal particles,current density and ion diffusion kinetics,and the volume changes of Li^(+) stripping/plating based on two physical contact models,and point out the direction for the future research direction of SSBs and advancing industrialization by building the relationship between pressures and SSBs electrochemistry.

The effect of volume change and stack pressure on solid-state battery cathodes

Solid-state lithium batteries may provide increased energy density and improved safety compared with Li-ion technology.However,in a solid-state composite cathode,mechanical degradation due to repeated cathode volume changes during cycling may occur,whichmay be partially mitigated by applying a significant,but often impractical,uniaxial stack pressure.Herein,we compare the behavior of composite electrodes based on Li4Ti5O12(LTO)(negligible volume change)and Nb2O5(+4%expansion)cycled at different stack pressures.The initial LTO capacity and retention are not affected by pressure but for Nb2O5,they are significantly lower when a stack pressure of<2MPa is applied,due to inter-particle cracking and solid-solid contact loss because of cyclic volume changes.Thiswork confirms the importance of cathode mechanical stability and the stack pressures for long-term cyclability for solid-state batteries.This suggests that low volumechange cathode materials or a proper buffer layer are required for solid-state batteries,especially at low stack pressures.