With the rapid development of power batteries and energy storage technologies, solid-state batteries have emerged as a key direction for next-generation energy devices and are attracting increasing attention from both academia and industry. Compared with conventional liquid-electrolyte batteries, solid-state batteries offer significant advantages, including enhanced safety, higher energy density, and longer cycle life. Among all components, the preparation and performance optimization of solid-state electrolytes are widely recognized as critical factors determining the practical performance of solid-state batteries.

Among various material processing techniques, high-energy ball milling has become an indispensable tool in solid-state battery research due to its high efficiency, excellent controllability, and broad applicability.

1. Principles and Characteristics of High-Energy Ball Milling

High-energy ball mills, such as the PULVERIZER 80, utilize high-speed rotational motion to generate intense impact and friction forces between milling balls and powder materials, enabling particle size reduction, homogeneous mixing, and even structural reconstruction.

The main characteristics of high-energy ball milling include:

        •      Impact and friction effects

Under high rotational speeds, the milling balls generate strong centrifugal forces, leading to repeated collisions and friction that effectively reduce particle size.

        •      High process controllability

By adjusting parameters such as rotational speed, revolution-to-rotation ratio, ball-to-powder ratio, milling media, and milling time, the particle size distribution, morphology, and structural state of powders can be precisely controlled.

        •      Wide material compatibility

High-energy ball milling is suitable for metals, ceramics, polymers, and composite systems, meeting the diverse material requirements of solid-state battery research.

For solid-state battery applications, this technique not only enables the production of nano- or even sub-nanometer-scale particles but also promotes uniform mixing and solid-solution reactions, significantly enhancing the ionic conductivity of solid electrolytes.

2. Application of High-Energy Ball Milling in Solid-State Electrolyte Preparation

Solid-state electrolytes can be broadly classified into sulfide-, oxide-, and halide-based systems, each benefiting differently from high-energy ball milling.

2.1 Sulfide Electrolytes

(e.g., Li₁₀GeP₂S₁₂, LGPS)

        •      High-energy ball milling can break precursor chemical bonds, induce amorphization, and accelerate solid-state reactions.

        •      Studies have shown that ball milling enables the synthesis of sulfide electrolytes with high ionic conductivity at relatively low temperatures, avoiding decomposition issues associated with high-temperature sintering.

2.2 Oxide Electrolytes

(e.g., Li₇La₃Zr₂O₁₂, LLZO)

        •     Conventional solid-state synthesis requires high-temperature sintering, while high-energy ball milling significantly shortens diffusion distances and enhances reaction kinetics.

        •      Improved powder homogeneity facilitates subsequent densification during sintering and reduces grain boundary resistance.

2.3 Halide Electrolytes

(e.g., Li₃YCl₆, Li₃InCl₆)

        •      Halide electrolytes are highly sensitive to moisture and oxygen, making wet-chemical synthesis challenging.

        •      High-energy ball milling conducted under inert atmospheres enables the direct preparation of high-purity halide electrolytes with stable crystal structures.

3. Application of High-Energy Ball Milling in Solid-State Battery Electrode Materials

In addition to electrolytes, high-energy ball milling also plays an important role in the preparation of solid-state battery electrode materials:

        •      Cathode materials

Materials such as LiCoO₂ and NCM series cathodes can be surface-coated or doped via high-energy ball milling, improving interfacial stability.

        •      Anode materials

Silicon- and tin-based anodes can be nanostructured through ball milling, mitigating volume expansion and enhancing cycling stability.

        •      Composite electrodes

High-energy ball milling promotes intimate contact between electrolytes and active materials, constructing efficient ion and electron transport pathways.

4. Influence of Process Parameters on Material Performance

The effectiveness of high-energy ball milling is closely related to processing parameters:

        •      Rotational speed

Insufficient speed leads to poor size reduction, while excessive speed may cause over-amorphization or contamination.

        •      Ball-to-powder ratio

Typically ranges from 10:1 to 30:1 and must be optimized for different material systems.

        •      Milling time

Short durations result in inadequate mixing, whereas excessive milling may degrade material properties.

        •      Atmosphere control

Sulfide and halide electrolytes must be processed under inert atmospheres (e.g., Ar) to prevent oxidation or hydrolysis.

Careful optimization of these parameters ensures structural stability while achieving optimal electrochemical performance.

5. Development Trends and Future Prospects

High-energy ball milling shows broad prospects in solid-state battery applications:

        •      Scale-up and industrialization

Transitioning from laboratory research to pilot-scale and industrial production.

        •      Integration with advanced processes

Combining with techniques such as mechanical alloying, cold spraying, and flash sintering to form hybrid processing routes.

        •      Process-driven material design

Increasing integration with computational modeling to achieve precise control over milling-induced structural evolution.

As solid-state batteries move closer to commercialization, high-energy ball milling is evolving from a laboratory research tool into a core industrial processing technology.

6. Conclusion

High-energy ball milling provides an efficient and versatile approach for the preparation of solid-state battery materials. It enables ultra-fine particle refinement, homogeneous mixing, and controlled solid-state reactions, thereby significantly improving the energy density, safety, and cycle life of solid-state batteries. Looking ahead, the integration of high-energy ball milling with other advanced manufacturing techniques will further accelerate the transition of solid-state batteries from laboratory research to large-scale industrial applications, injecting strong momentum into the future of renewable energy technologies.