Lithium metal batteries (LMBs), that use pure lithium (Li) for their negative electrodes, are attracting significant attention due to their extremely high theoretical capacity. However, their practical applications are limited by low cycling stability and safety issues, arising from dendrite formation, electrolyte breakdown and uneven solid-electrolyte interface formation.
Solid-state electrolytes are a promising solution to address these challenges. They offer electrochemical stability, mechanical flexibility and manufacturing advantages. Despite these advantages, their practical implementation is hindered by low ionic conductivity, which impedes lithium-ion mobility and exacerbates interfacial issues with lithium-metal anodes.
Now, a research team led by Professor Mincheol Chang from the Department of Polymer Engineering and the School of Polymer Science and Engineering at Chonnam National University, South Korea, has now developed a new tri-layer composite solid electrolyte (CSE). A composite solid electrolyte (CSE) is an advanced battery material that blends a polymer matrix with inorganic ceramic fillers to safely conduct lithium ions without flammable liquid solvent.
“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” said Professor Chang. The study was published in Volume 38, Issue 43 of Advanced Materials on 3rd August.
In experiments, the optimised CSE-30 design 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 1000 hours of stable, dendrite free cycling. In full cell tests, it delivered an impressive capacity of 133.6 mAhg-1 with over 80 percent capacity retention after 1000 charging/discharging cycles.
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” added Professor Chang.
Overall, this innovative tri-layer design offers a practical blueprint for developing safer, longer-lasting batteries, paving the way for lithium-metal batteries in electric vehicles, consumer electronics, wearable devices, and grid-scale energy storage.
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