Progress and Perspectives on the Development of Pouch-Type Lithium Metal Batteries.

Lithium (Li) metal batteries (LMBs) are the "holy grail" in the energy storage field due to their high energy density (theoretically >500 Wh kg-1 ). Recently, tremendous efforts have been made to promote the research & development (R&D) of pouch-type LMBs toward practical application. This article aims to provide a comprehensive and in-depth review of recent progress on pouch-type LMBs from full cell aspect, and to offer insights to guide its future development. It will review pouch-type LMBs using both liquid and solid-state electrolytes, and cover topics related to both Li and cathode (including LiNix Coy Mn1-x-y O2 , S and O2 ) as both electrodes impact the battery performance. The key performance criteria of pouch-type LMBs and their relationship in between are introduced first, then the major challenges facing the development of pouch-type LMBs are discussed in detail, especially those severely aggravated in pouch cells compared with coin cells. Subsequently, the recent progress on mechanistic understandings of the degradation of pouch-type LMBs is summarized, followed with the practical strategies that have been utilized to address these issues and to improve the key performance criteria of pouch-type LMBs. In the end, it provides perspectives on advancing the R&Ds of pouch-type LMBs towards their application in practice.

Accurate transition state generation with an object-aware equivariant elementary reaction diffusion model.

Transition state search is key in chemistry for elucidating reaction mechanisms and exploring reaction networks. The search for accurate 3D transition state structures, however, requires numerous computationally intensive quantum chemistry calculations due to the complexity of potential energy surfaces. Here we developed an object-aware SE(3) equivariant diffusion model that satisfies all physical symmetries and constraints for generating sets of structures-reactant, transition state and product-in an elementary reaction. Provided reactant and product, this model generates a transition state structure in seconds instead of hours, which is typically required when performing quantum-chemistry-based optimizations. The generated transition state structures achieve a median of 0.08 Å root mean square deviation compared to the true transition state. With a confidence scoring model for uncertainty quantification, we approach an accuracy required for reaction barrier estimation (2.6 kcal mol-1) by only performing quantum chemistry-based optimizations on 14% of the most challenging reactions. We envision usefulness for our approach in constructing large reaction networks with unknown mechanisms.

Noise-induced quasiperiod and period switching.

We employ a typical genetic circuit model to explore how noise can influence dynamic structure. With the increase of a key interactive parameter, the model will deterministically go through two bifurcations and three dynamic structure regions. We find that a quasiperiodic component, which is not allowed by deterministic dynamics, will be generated by noise inducing in the first two regions, and this quasiperiod will be more and more stable along with the increase in noise. In particular, in the second region the quasiperiod will compete with a stable limit cycle and perform a new transient rhythm. Furthermore, we ascertain the entropy production rate and the heat dissipation rate, and discover a minimal value with theoretical elucidation. In the end, we unveil the mechanism of the formation of quasiperiods, and show a practical biological example. We expect this work to be helpful in solving some biological or ecological problems, such as the genetic origin of periodical cicadas and population dynamics with fluctuation.

Piezoelectric and polarized enhancement by hydrofluorination of penta-graphene.

Motivated by the challenges in the harnessing of energy and the continuing trend of miniaturizing devices, an exhaustive evaluation of the electronic, mechanical and piezoelectric properties of surface modified penta-graphene (PG), including fluorinated PG (F-PG-F), hydrofluorinated PG (H-PG-F) and hydrogenated PG (H-PG-H), was carried out via a first-principles approach based on density functional theory. We first predicted the H-PG-F system and calculated its phonon dispersion and magnetic properties. All three systems were found to exhibit an e31 piezoelectric effect, and the e31 (96.88 pC m-1) effect of H-PG-F was found to be much greater than that of the other two systems. So, it could be concluded that hydrofluorination can significantly enhance the piezoelectric properties of PG. The binding energy and formation energy of the H-PG-F system were found to be the lowest among the three surface modified PG systems, showing that the H-PG-F system is the most energetically favorable state. The e31 piezoelectricity can be potentially engineered into a PG monolayer by surface modification, providing an avenue for monolithic integration of electronic and electromechanical devices with a PG monolayer for use in mechanical stress-sensors, nano-sized actuators and energy harvesting systems. The H-PG-F system stands out in terms of its combination of a larger piezoelectric coefficient (e31 = 96.88 pC m-1), negative Poisson's ratio and low formation energy (-3.37 eV) and is recommended for experimental exploration.