Chonnam National University researchers have developed a tri-layer composite solid electrolyte intended to improve the safety, durability and service life of lithium-metal batteries. Led by Professor Mincheol Chang, the South Korean team combined flexible polymer layers with a ceramic-reinforced central layer to improve ion transport while resisting lithium dendrite formation. In testing, the optimised electrolyte delivered nearly four times the ionic conductivity of plain PEO, stable dendrite-free cycling for more than 1,000 hours, and over 80% capacity retention after 1,000 full-cell cycles. The work, published in Advanced Materials, points to a promising materials route for electric vehicles, flexible electronics and stationary energy storage.

Addressing Lithium Metal Limits

Lithium-metal batteries use pure lithium as their negative electrode material and are of interest because of their extremely high theoretical capacity. Their wider application has, however, been constrained by low cycling stability and safety concerns associated with dendrite growth, electrolyte breakdown and uneven solid-electrolyte interface formation.

Solid-state electrolytes offer an alternative to conventional liquid systems, with electrochemical stability, mechanical flexibility and manufacturing advantages among their potential benefits. Yet low ionic conductivity can restrict lithium-ion movement and worsen interfacial challenges at lithium-metal anodes. The Chonnam National University study focuses on overcoming that trade-off through a composite structure designed to bring conductivity and mechanical strength together.

Professor Mincheol Chang, Professor in the Department of Polymer Engineering and the School of Polymer Science and Engineering at Chonnam National University, said:

“Inspired by the natural adhesive proteins mussels use to stick to rocks, our tri-layer composite incorporates chemically active ceramic fillers with a flexible triblock copolymer, boosting ionic conductivity and mechanical strength.”

Three Layers With Distinct Roles

The proposed membrane places soft outer layers of PEO and lithium bis(trifluoromethanesulfonyl)imide, known as LiTFSI, around a harder central layer. The outer materials are intended to make close contact with the electrodes while creating pathways for lithium-ion transport.

At its centre, the electrolyte uses polydopamine-coated Li7La3Zr2O12 particles, or PDA@LLZO, alongside poly(ethylene glycol)-block-poly(propylene glycol)-block-poly(ethylene glycol), referred to as PPP. The ceramic additive and ductile polymer form the conductive, mechanically robust backbone of the design.

The PDA coating is designed to promote lithium-ion mobility through hydrogen-bond coupling with PEO chains and through percolating conduction pathways. It also selectively interacts with TFSI ions, increasing the concentration of lithium ions. PPP contributes elasticity to the hybrid network, helping the material resist lithium dendrite growth while maintaining flexibility.

Measured Gains In Cycling

The research team fabricated the tri-layer membrane through solvent-assisted dispersion, tape casting, thermal lamination and hot pressing. Its optimised CSE-30 configuration contained 30% by weight of PDA@LLZO and used equal layer thicknesses.

That design achieved ionic conductivity nearly four times higher than plain PEO. It also reached a lithium transference number of 0.81, a measure of how efficiently lithium ions move through the electrolyte. In symmetric-cell testing, CSE-30 maintained stable dendrite-free cycling for more than 1,000 hours.

Full-cell testing produced a capacity of 133.6 mAhg-1 and retained more than 80% of capacity after 1,000 charging and discharging cycles. Such results address two closely related requirements for battery development: maintaining performance over repeated use while reducing failure risks linked to dendrite formation.

Flexibility For Practical Devices

The material was also assessed in a flexible pouch-cell configuration. The cell continued to power an LED when folded or partially cut, providing a demonstration of its mechanical durability and functional reliability under physical stress.

That flexibility broadens the relevance of the electrolyte beyond vehicle batteries. Wearable devices and other electronics can require energy-storage components that continue working in compact or flexible form factors, while grid-scale systems need long cycle life and dependable operation.

Professor Mincheol Chang, Professor in the Department of Polymer Engineering and the School of Polymer Science and Engineering at Chonnam National University, remarked:

“Our electrolyte is designed for next-generation lithium-metal batteries that can enable longer driving ranges for electric vehicles, safer batteries, flexible and wearable electronics, and long-cycle-life grid-scale energy storage,”

A Materials Blueprint

The tri-layer approach offers a clear example of how polymer engineering and ceramic additives can be combined to tackle the interrelated conductivity, durability and safety constraints facing lithium-metal batteries. Rather than relying on a single material to perform every function, the architecture assigns electrode contact, ion transport and structural reinforcement across distinct layers.

For battery developers, the reported results position the material as a useful blueprint for safer, longer-lasting lithium-metal cells. Its performance in both repeated cycling and flexible pouch-cell testing suggests potential across electric vehicles, consumer electronics, wearable devices and grid-scale energy storage, where dependable storage technologies remain central to wider electrification.