A Revolution in Solid-State Electrolyte Design: Prof. Xueliang Sun's Team Unveils "Solid Dissociation" Paradigm to Unlock a Universe of Superionic ConductorsIntroduction

Solid-state electrolytes (SSEs) are considered key to next-generation energy storage due to their high safety and potential for high energy density. However, their development has long been plagued by a core bottleneck: the lack of flexible "electrolyte engineering." Unlike liquid electrolytes, where solvents and salts can be flexibly tuned, the superionic conduction in traditional SSEs relies on rigid, specific crystal structures. Any "suboptimal" doping or modification often disrupts their ionic pathways, causing performance to plummet. This has made tailoring high-performance SSEs for specific applications (like low-temp, fast-charging, or high-voltage) extremely difficult.

Recently, a breakthrough study published in Nature Energy by Prof. Xueliang Sun and Assoc. Prof. Xiaona Li from Ningbo Institute of Technology, Eastern, along with Dr. Jianwen Liang from GRINM (Guangdong), introduces a revolutionary solution. They propose a novel "solid dissociation" strategy that cleverly mimics the dissolution process of liquids within a solid state, breaking the design limitations of conventional SSEs and unlocking a vast library of over 70 new superionic conductors.

The Core Breakthrough: "Solid Dissociation" – Simulating Liquid Solvation in a Solid

The strategy's inspiration comes from the dissolution mechanism in liquid electrolytes: a liquid solvent uses its reconfigurable molecular environment, weak intermolecular forces, and strong solvation sites to "dismantle" an ionic crystal lattice, allowing ions to move freely.

Using this as a blueprint, the research team searched for a "solid solvent" with similar properties. They identified van der Waals (vdW) crystals, M(Oₘ)Clₙ, as the ideal candidates. These materials perfectly meet all the criteria:

1. Weak Interactions: The material is held together by weak vdW forces, providing a low-energy barrier for ion diffusion (analogous to weak intermolecular forces in a liquid).

2. Strong Coordination Sites: The material contains strongly Lewis-acidic metal cations (M) that can powerfully "grasp" and "dismantle" the anions of a salt (analogous to solvation in a liquid).

   
   

Through simple mechanical ball milling, this "solid solvent" can "dissolve" and dissociate various metal salts (e.g., Li, Na salts), creating a new, amorphous, liquid-like electrolyte material.

Schematic of the liquid-phase dissolution and solid-phase dissociation processes

The Result: A New "Material Library" of Superionic Conductors

The "solid dissociation" strategy is exceptionally versatile. The team demonstrated its use in dissociating salts of various cations (Li⁺, Na⁺, Ag⁺, Cu⁺) and a wide range of anions (from simple S²⁻ to complex polyanions like BF₄⁻).

This breakthrough platform technology instantly unlocks a massive new "material universe" of novel electrolytes:

• Over 70 new SSEs were successfully synthesized.

• Over 40 of these materials exhibit room-temperature ionic conductivity greater than 1 mS cm⁻¹ (the standard for superionic conduction).

• The highest conductivity exceeds 10 mS cm⁻¹, a value comparable to commercial liquid electrolytes.

Room-temperature ionic conductivity of the solid dissociation electrolytes

Unveiling the Mechanism: From "Long-Range Disorder" to "Lithium Bond" Transport

Why do these new materials have such high conductivity? The team used advanced characterization to reveal their unique structure:

• Long-Range Disorder, Short-Range Order: PDF analysis showed that the materials are "disordered" over long ranges, much like a liquid, but maintain a specific "ordered" coordination in their local structure.

Long-range and local structure of the solid dissociation electrolytes

• The Formation of "Lithium Bonds": ⁷Li NMR and AIMD simulations further revealed that the key to superionic conduction is the formation of a low-coordination, distorted [LiClₓ] configuration. In this structure, the Li⁺ forms a low-coordination, weak "lithium bond" with the lone-pair electrons of Cl⁻.

Lithium environment in the solid dissociation electrolytes

The ionic conductivity is directly correlated with the formation and evolution of this "Li-bond-rich" environment. It is through the rapid formation and breaking of these weak "lithium bonds" that Li⁺ achieves fast, liquid-like mobility within the disordered solid matrix.

Evolution of the local structure and its relationship with ionic conduction

The Ultimate Impact: Enabling True "Solid-State Electrolyte Engineering"

The greatest significance of the "solid dissociation" strategy is that it enables "electrolyte engineering" in solid-state systems for the first time, much like in liquid electrolytes. By flexibly tuning the "solute" and "solid solvent" components, electrolytes can now be custom-designed for specific functions.

The team demonstrated this powerful new capability with four practical applications, successfully developing designer SSEs for:

1. Ultra-fast Charging: Enabling 15 C fast charge/discharge.

2. Ultra-low Temperature: Operating at an extreme –50 °C.

3. High Voltage: Stably matching 4.8 V high-voltage cathodes.

4. High Stability & Low Cost: Possessing superior air stability, dry-room compatibility, and a more competitive cost.

Ultrafast-charging/discharging and low-temperature all-solid-state batteries

Solid dissociation electrolytes with high oxidation stability, high air stability, and low cost

Conclusion and Outlook

This research presents a new paradigm for the solid-state electrolyte field, moving beyond the rigid constraints of crystalline lattices. The "solid dissociation" strategy provides unprecedented flexibility and design freedom, allowing researchers to "formulate" optimal SSEs for various applications, just as they do with liquid electrolytes. This concept is poised to fundamentally accelerate the practical application of high-performance solid-state batteries and other ionic devices.

Literature Information

Yue, J.; Zhang, S.; Wang, X.; Fu, J.; Xu, Y.; Weng, S.; Zhu, Y.; Zhao, C.; Zheng, M.; Wang, Y.; Zhu, X.; Wu, H.; Wang, G.; Xia, Y.; Cao, M.; Jing, Q.; Wang, X.; Xia, W.; Liang, J.; Sun, X.; Li, X.; Universal superionic conduction via solid dissociation of salts in van der Waals materials. Nature Energy 2025, Doi: 10.1038/s41560-025-01853-2.

Author Biographies

• Xueliang Sun: Foreign Member of the Chinese Academy of Engineering, Fellow of the Royal Society of Canada, Fellow of the Canadian Academy of Engineering. He is a Chair Professor at Ningbo Institute of Technology, Eastern. His research focuses on solid-state batteries, Li-ion batteries, and fuel cells, and he has been named a Clarivate "Global Highly Cited Researcher" for 6 consecutive years.

• Xiaona Li: Associate Professor at Ningbo Institute of Technology, Eastern, and recipient of the National Overseas High-Level Young Talents award. Her research focuses on solid-state electrolyte synthesis and all-solid-state lithium batteries. She was named to the "MIT Technology Review Innovators Under 35 China" list in 2023.

• Jianwen Liang: Director of the Solid-State Battery Research Center at GRINM (Guangdong) and recipient of the National "Overseas High-Level Young Talents Project." His research focuses on all-solid-state Li-ion batteries, including inorganic solid-state electrolytes.

• Junyi Yue: Joint Ph.D. student between Hong Kong Polytechnic University and Ningbo Institute of Technology, Eastern, focusing on halide solid-state electrolytes.

• Simeng Zhang: Associate Researcher at Ningbo Institute of Digital Twin (Oriental Institute of Technology). His research focuses on the development of halide solid-state electrolytes and all-solid-state batteries.