Atomic layer deposition for protecting lithium metal anodes to high-voltage battery applications

Lithium metal anodes, with their high theoretical capacity and low electrochemical potential, hold great promise for next-generation batteries. However, challenges such as dendrite formation, interfacial instability, and high volume expansion hinder their practical use. This study applies atomic layer deposition (ALD) of alumina (Al 2 O 3 ) on lithium to optimize the protective coatings, enhancing anode performance and stability. Advanced techniques, including in-situ optical dendrite imaging and operando electrochemical dilatometry, provided fresh insights into interfacial stability and dendrite suppression mechanisms. Results reveal that thicker Al 2 O 3 coatings (150 ALD cycles) significantly improve battery cycling stability compared to thinner coatings (25 ALD cycles), suppressing dendrite growth and maintaining low overpotentials after 200 charge-discharge cycles. Operando electrochemical dilatometry reveals that the Al 2 O 3 coated lithium exhibits reduced and more uniform volume fluctuations compared to uncoated lithium, highlighting the stabilizing effect of the coating. Pairing the thickly coated anodes with LiN 0.8 Mn 0.1 Co 0.1 O 2 cathodes demonstrate a 32 % improvement in capacity retention over uncoated-Li at the current density of 200 mA g −1 after 200 cycles. This study not only elucidates the relationship between the coating thickness and electrode performance but also highlights the potential of engineered ALD coatings to overcome the critical barriers to the practical deployment of high-energy lithium-metal batteries. This study demonstrates how atomic layer deposition of alumina enhances lithium-metal anodes by stabilizing the interfaces, suppressing dendrite growth, and improving long-term cycling stability in high-voltage Li||NMC811 cells. • Atomic layer deposition applied for coating lithium metal. • Al 2 O 3 coatings enhance the lithium metal anode stability and cycle life. • Thicker coatings suppress dendrite growth and maintain a stable interface. • Al 2 O 3 -coated Li full cells achieve 96 % capacity retention after 200 cycles. • Operando dilatometry confirms reduced volume fluctuations in coated lithium.