Dual-gradient metal layer for practicalizing high-energy lithium batteries

Pairing high-energy nickel-rich cathodes with current collectors as anodes presents a compelling strategy to significantly boost the specific energy of rechargeable lithium-ion batteries, driving progress toward a transportation revolution. However, the limited active lithium inventory sourced by the cathodes tend to be rapidly consumed by irreversible Li plating/stripping and interfacial side reactions. To address these limitations, we propose a dual-gradient metal layer as an innovative solution to mitigate active Li loss by promoting uniform Li deposition and in situ formation of a stable solid electrolyte interphase. The operation of these batteries is investigated using a combination of electrochemical and chemical techniques to differentiate dead Li and interphase-bound Li inventory loss as well as material characterization methods to analyse the plated Li and interfacial composition and morphology. The developed dual gradient metal layer-based 600 mAh LiNi_0.9Co_0.05Mn_0.05O₂ | |Cu pouch cells achieve an areal capacity of 7.25 mAh cm^-2 and deliver an 80% capacity retention over 160 cycles. We show that the proposed approach is compatible with a range of different metal materials, offering a promising path toward next generation long-lasting, high-energy, initially active material-free anode based Li metal batteries.