Metallic lithium is the ideal anode material for rechargeable batteries. Replacing the graphite anode with metallic lithium is one of the most promising strategies to improve the energy densities of the current rechargeable lithium ion batteries (LIBS).
However, the current lithium metal batteries (LMBs) are still plagued by low coulombic efficiency, fast capacity degradation, and safety hazards. While the detailed mechanisms are still under intensive investigations, the parasitic reactions between metallic lithium and the electrolyte, the piercing and rebuilding of solid solid-electrolyte interphases (SEIs), and the growth of dendrites are recognized as the major sources of instability.
A research group led by Dr. LU Ziheng and Dr. YANG Chunlei from the Shenzhen Institutes of Advanced Technology (SIAT) of the Chinese Academy of Sciences developed a facile and scalable approach to stabilize the lithium metal anode by regulating the Li nucleation and deposition kinetics with laser-induced graphene (LIG).
Novel current collector based on laser-induced-graphene and the electrochemical performance of a the lithium metal battery (Image by LU Ziheng)
The researchers constructed a 3D-hierarchical composite material by processing polyimide films on copper foils with a laser, which consisted of a highly conductive copper substrate, a pillared array of flexible polyimide, and most importantly, porous LIG on the walls of the polyimide pillars.
The high number of defects and heteroatoms present in LIG significantly lowered the Li nucleation barrier compared to the copper foil. An overpotential-free Li nucleation process was identified at current densities lower than 0.2 mA/cm2.
Theoretical computations revealed that the defects served as nucleation centers during the heterogeneous nucleation of lithium. By adopting such composites, ultrastable lithium metal anodes were obtained with high coulombic efficiencies of ~ 99%.
Full lithium-metal cells based on LiFePO4 cathodes with a material loading of ~15 mg/cm2 and a negative/positive ratio of 5/1 could be cycled over 250 times with a capacity loss of less than 10%.
The current work highlights the importance of nucleation kinetics on the stability of metallic anodes and demonstrates a practical method toward long lasting Li metal batteries.
The study entitled "Facile Patterning of Laser-induced-Graphene with Tailored Li Nucleation Kinetics for Stable Lithium Metal Batteries" was published in Advance Energy Materials.
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