Novel ZIF-based heterojunction filler boosting Li-ion transport of composite solid-state electrolytes

The demand for safer and higher-performing lithium metal batteries (LMBs) is driving innovation in solid-state electrolyte (SSE) technology. Traditional liquid electrolytes pose safety hazards due to their flammability, while many existing solid-state electrolytes face limitations such as low ionic conductivity and poor lithium-ion transference numbers. Composite solid electrolytes (CSEs), particularly those based on poly (vinylidene fluoride) (PVDF), offer advantages in manufacturing, flexibility, and cost, but still require improved ion transport.

A team of materials scientists from Tsinghua University in Shenzhen, China, led by Professor Yan-Bing He and Dr. Peiran Shi, has engineered a novel heterojunction nanoparticle filler that addresses these challenges. Their work, published in Energy Materials and Devices, introduces TiO₂@Zn/Co−ZIF (titanium oxide coupled with bimetallic zeolitic imidazolate frameworks) as a highly effective additive for PVDF-based composite solid-state electrolytes (PVZT). The resulting electrolytes demonstrates exceptional ionic conductivity and interfacial stability.

“By integrating the Lewis acidic properties of TiO₂ with the structural confinement of ZIFs, we’ve created a dual-function material that facilitates both lithium salt dissociation and ion transport,” said Prof. He, corresponding author from the Institute of Materials Research at Tsinghua Shenzhen International Graduate School.

The PVZT composite achieves a room-temperature ionic conductivity of 8.8 × 10⁻⁴ S·cm⁻¹ and a lithium-ion transference number of 0.47. These enhancements stem from the synergistic effect of TiO₂’s ability to bind anions and ZIFs’ nanoporous structure, which selectively channels lithium ions while suppressing anion movement.

In performance tests, Li||Li symmetric cells using PVZT cycled stably for over 1100 hours, and Li||NCM811 full cells retained 75% capacity after 1200 cycles at a 2C rate, demonstrating it as a promising candidate for long-term operation. Additionally, the PVZT electrolyte effectively mitigates lithium dendrite growth and reduces interfacial degradation.

“Our strategy provides a scalable path for fabricating high-performance solid electrolytes using zeolitic imidazolate framework,” Dr. Shi stated. “This could accelerate the commercial development of safer and more stable solid-state batteries.”

This research, published in Energy Materials and Devices on June 16, 2025, presents a promising direction for the design of functional fillers in composite solid electrolytes. The study was supported by several national and regional science programs, including the National Key R&D Program of China and the National Science Fund for Distinguished Young Scholars.

Other contributors include Jianshuai Lv, Yuhang Li, Ke Yang, Xinyu Liu, Ying Dou, Zheng Zhang, Danfeng Zhang and Ming Liu from the Institute of Materials Research at Tsinghua Shenzhen International Graduate School at Tsinghua University in Shenzhen, China.

This work was supported by the National Science Fund for Distinguished Young Scholars (No.52325206). This work was supported by the National Key Research and Development Program of China (2021YFF0500600), National Natural Science Foundation of China (No. U2001220 and 52203298), Shenzhen Technical Plan Project (Nos. RCJC20200714114436091, JCYJ20220530143012027, JCYJ20220818101003008 and JCYJ20220818101003007), Tsinghua Shenzhen International Graduate School-Shenzhen Pengrui Young Faculty Program of Shenzhen Pengrui Foundation (No.SZPR2023006) and Shenzhen Science and Technology Program (WDZC20231126160733001).

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