Uniform lithium deposition using Cu teepee structures for anode-free lithium metal batteries

Abstract

Anode-free lithium metal batteries (AFLMBs) with nickel-enriched cathodes are emerging as the next generation of secondary batteries, aiming to surpass the energy density limits of conventional lithium-ion batteries (100–250 Wh kg−1). However, their low Coulombic efficiency and rapid capacity decay, caused by heterogeneous nucleation and growth of lithium, have hindered the commercialization of AFLMBs. To mitigate these challenges, we propose a Cu teepee (Cu TP) structure as an anodic current collector where nano teepee structures induce the homogeneous nucleation and growth of lithium on the current collector to achieve a dense and smooth lithium morphology. Compared to a bare Cu current collector, the Cu TP current collector enhances lithium-ion transport, wettability, and electrochemically accessible surface area, leading to more uniform and controlled lithium growth even at high current densities. Furthermore, anode-free coin cells comprising a Cu TP current collector and an NMC622 cathode were tested under conditions with limited electrolyte. These cells deliver the discharge capacity of 149.9 mAh g−1 at 3C and retain 88.1 % of their initial capacity after 140 cycles with a remarkable energy density of 672.64 Wh kg−1.