The rapid evolution of battery technology has brought the world closer to realizing the potential of solid-state batteries (SSBs). While these batteries promise significant advancements, particularly in safety and energy density, they are still navigating a series of technical challengesCurrently, the solid-state battery market is in its infancy, with China selecting a more gradual path toward commercialization through hybrid (solid-liquid) battery technology, as opposed to the more radical full solid-state technology approach that holds disruptive potential.

At its core, solid-state lithium batteries utilize solid electrolytes instead of liquid onesThis fundamental shift brings with it significant advantages, such as enhanced safety features and increased energy density, positioning solid-state technology as a key trend in battery developmentThe classification of solid-state batteries bifurcates into hybrid and full solid-state categories based on electrolyte type, with the latter proving more complex and challenging due to materials and interface issues.

Countries like Japan and South Korea, alongside various nations in Europe and North America, pioneered the research and development of solid-state batteries, focusing primarily on fully solid-state designsHowever, driven by market demands and practical application considerations, China has opted to progress using hybrid batteries as a transitional approach, marking a pragmatic step in the journey towards a more stable and scalable battery solution.

Hybrid batteries maintain a small amount of liquid electrolyte, which serves to significantly resolve interface contact issues inherent in solid-solid configurationsThis hybrid design not only enhances safety but also improves energy density, creating pathways for earlier commercializationThe China Automotive Power Battery Industry Innovation Alliance reported an installation volume of 2,154.7 MWh for hybrid systems in the first half of 2024, showcasing the market's active embrace of this technology.

The evolutionary pathway within the solid-state battery landscape focuses on gradually transitioning towards full solid-state production via in-situ solidification technology

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The manufacturing process for these advanced batteries comprises several phases, including the production of electrode sheets and solid electrolyte membranes, as well as the assembly and formation of the battery cells themselvesEach stage must adapt to the specific materials and structural requirements that come with solid-state designs.

Manufacturing processes can be categorized into two main techniques: wet and dry methodsCurrently, the wet method is more feasible for mass productionHowever, the dry method—with its advantages of low energy consumption, reduced costs, and high energy density—is expected to gain traction and stages of adoption over time.

Looking at the more advanced processes, battery cells made from oxide and sulfide solid-state materials often require pressurization to enhance solid-solid contactConsequently, soft-pack stacking is anticipated to become the dominant techniqueThis will consequently give rise to new innovations in cell assembly methods, such as integrated stacking, isostatic pressing, and bipolar architecture, while necessitating even higher pressure during the formation stage.

As the manufacturing processes evolve, the equipment needed to support them must also changeAnalyzing the three phases of equipment—initial, intermediate, and final—suggests a significant transformation in their requirementsFor instance, dry processing equipment including dry mixing apparatus, fiberization machinery, granulation units, and film fabrication technology is expected to gradually take over from wet processing equipmentAdditionally, the introduction of thermal composite devices for the electrolyte is foreseen to complement this shift.

The increased complexity associated with solid-state manufacturing methods also means that various processes performed by rolling equipment, such as film formation and thermal composites, will require more advanced technology and capabilitiesThis anticipated equipment evolution could lead to a dual increase in both value and volume.

In the latter stages of production, changes include the phasing out of liquid injection systems and the rise of stacking systems taking precedence over traditional winding machines

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