Lithium-metal battery dendrite-free cycling clocks 1,000 hours

Researchers from Chonnam National University (CNU), South Korea have demonstrated 1,000 hours of dendrite-free cycling in lithium-metal batteries (LMBs) through the development of a new tri-layer solid electrolyte, which combines flexible polymers and ceramic particles.

With potential to support grid-scale energy storage and electric vehicles (EVs), the research found ionic conductivity was nearly four times higher than plain polyethylene oxide (PEO), the electrolyte achieved a high lithium-ion transference number of 0.81, and the lithium-metal cells demonstrated 1,000 hours of stable, dendrite-free cycling.

Full cells also retained over 80% of their capacity after 1,000 cycles and a flexible pouch cell continued powering an LED even after being folded or partially cut.

Research lead, CNU Department of Polymer Engineering Professor Michneol Chang said the study was 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,” Chang said.

The proposed tri-layer architecture consists of soft outer layers made of a PEO/lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) matrix surrounding a central hard layer reinforced with polydopamine (PDA)-coated Li₇La₃Zr₂O₁₂ (LLZO) particles as the ceramic additive and poly(ethylene glycol)-block- poly(propylene glycol)-block-poly(ethylene glycol) (PPP) as a ductile polymeric component.

The tri-layered membrane was fabricated through solvent-assisted dispersion, tape casting, thermal lamination, and hot pressing. The soft outer layers are designed to offer intimate contact with electrodes and Li⁺ transport channels. Meanwhile, the central PDA@LLZO-PPP layer forms a mechanically robust and highly conductive backbone.

Specifically, the chemically active PDA-coated LLZO (PDA@LLZO) particles improve Li⁺ – ion mobility through hydrogen bond-coupling between PDA and PEO chains and percolating conduction pathways. PDA also improves Li⁺-ion concentration by selectively interacting with TFSI ions.

The flexible PPP polymer reinforces the hybrid network, improving its mechanical elasticity while helping suppress lithium dendrite growth.

The researchers found the optimised CSE-30 design with 30% by weight of PDA@LLZO incorporation and equal layer thicknesses, achieved nearly four times higher ionic conductivity over plain PEO.

“It also demonstrated a high lithium transference number (a measure of efficient Li-ion transport) of 0.81. In symmetric cell tests, CSE-30 offered over 1,000 hours of stable, dendrite free cycling. In full cell tests, it delivered an impressive capacity of 133.6 mAhg with over 80% capacity retention after 1000 charging/discharging cycles,” the researchers said.

Additionally, in a flexible pouch-cell configuration, even when the cell was folded or partially cut, it continued powering an LED, demonstrating both mechanical durability and functional reliability.

“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,” Chang said.

The ‘Surface-Functionalised LLZO-Incorporated Multilayer Composite Solid Electrolytes for Dendrite Suppression and Efficient Ionic Conduction in Lithium–Metal Batteries’ study is published in Advanced Materials.