Li metal batteries (LMBs) have attracted widespread attention in recent years because of their high energy densities. But traditional LMBs using liquid electrolyte have potential safety hazards, such as: leakage and flammability. Replacing liquid electrolyte with solid polymer electrolyte (SPE) can not only significantly improve the safety, but also improve the energy density of LMBs. However, till now, there is only limited success in improving the various physical and chemical properties of SPE, especially in thickness, posing great obstacles to further promoting its fundamental and applied studies. In this review, the authors mainly focus on evaluating the merits of ultrathin SPE and summarizing its existing challenges as well as fundamental requirements for designing and manufacturing advanced ultrathin SPE in the future. Meanwhile, the authors outline existing cases related to this field as much as possible and summarize them from the perspective of synthetic chemistry, hoping to provide a comprehensive understanding and serve as a strategic guidance for designing and fabricating high‐performance ultrathin SPE. Challenges and opportunities regarding this burgeoning field are also critically evaluated at the end of this review.

The hot deformation behavior of a nitrogen-bearing martensitic stainless steel was researched by the isothermal compression test in the temperature range of 950–1150 °C and strain rate range of 0.01–10 s⁻¹ with a Gleeble-3800 thermal-mechanical simulating tester. A strain compensated sine-hyperbolic Arrhenius-type constitutive equation was developed to describe the relationship between true stress and deformation parameters such as temperature, strain rate and true strain. The hot deformation activation energy is calculated to be from 407 to 487 KJ mol⁻¹. It is validated by the standard statistical parameters that the established constitutive equation can accurately predict the true stress. The processing maps at different true strains were constructed based on the dynamic material model (DMM) and the true stress data obtained from the hot compression tests. Two unstable regions which should be avoided during hot working were observed from the processing map. In addition, the optimum hot working parameters are located in the domain of 1000–1150 °C/0.1–1 s⁻¹ with the peak power dissipation efficiency of 39.9%, in which complete dynamic recrystallization (DRX) occurs.

In this paper, the electrochemical corrosion behavior of X70 steel in saline soil under capillary water was simulated by a Geo-experts one-dimensional soil column instrument. A volumetric water content sensor and conductivity test were used to study the migration mechanism of water and salt (sodium chloride) under the capillary water. The electrochemical corrosion behavior of the X70 steel in the corrosion system was analyzed by electrochemical testing as well as the macroscopic and microscopic corrosion morphology of the steel. The test results showed that the corrosion behavior of X70 steel was significantly influenced by the rise of capillary water. In particular, the wetting front during the capillary water rise meant that the X70 steel was located at the three-phase solid/liquid/gas interface at a certain location, which worsened its corrosion behavior. In addition, after the capillary water was stabilized, the salts were transported with the capillary water to the top of the soil column. This resulted in the highest salt content in the soil environment and the most severe corrosion of the X70 steel at this location.

The extensive use of coal in the steel metallurgy sector has resulted in significant greenhouse gas emissions. Hydrogen-rich gases have been introduced to partially replace coal in the blast furnace reduction process to mitigate this issue. This research explores using abundant coalbed methane (CBM) resources near steel plants for metallurgical applications. Addressing the challenge of determining optimal process parameters in hydrogen-rich blast furnace smelting, this project first develops an energy and mass balance model for the hydrogen-rich blast furnace, providing a foundation for process analysis. Using this model, the substitution ratio and oxygen enrichment rate of the blast furnace are calculated under varying preheating temperatures of coalbed methane. Additionally, this study assesses carbon dioxide emission patterns based on the elemental balance principle, emphasizing the potential of coalbed methane to reduce carbon emissions and support low-carbon metallurgical development.