2D Metal-Oxide Nanosheets as a Homogeneous Li-Ion Flux Regulator for High-Performance Anodeless Lithium Metal Batteries.

ABSTRACT

The anodeless battery design has recently gained significant interest by eliminating the direct use of a thick lithium (Li) foil. However, it suffers from inhomogeneous Li+ flux, resulting in dendrite growth and a short cycling life. To address this, the exfoliation of layered-structure titanium oxide to 2D nanosheets (2DTiOx) is proposed to precisely control Li+ flux at the atomic scale by maximizing Li+ affinitive Ti sites. Compared to cells without these nanosheets, the Li|2DTiOx|Cu half-cell demonstrates stable cyclability over 900 cycles, with a Coulombic efficiency (CE) over 99% at 0.5 mA cm-2 and 0.5 mAh cm-2. Similarly, a long stable cycling life over 1500 h at 1.0-3.0 mA cm-2 is observed for a 2DTiOx-based symmetric cell containing a limited Li amount from electrodeposited Li metal (e-Li|2DTiOx|e-Li). The full cells (e-Li|2DTiOx||NCM811 and e-Li|2DTiOx||LFP) coupled with NCM811 and LFP cathodes showed a long cycle life of 400 cycles at 1.0 C and 0.5 C, respectively. The exceptional battery performance is attributed to the uniform Li disposition on the 2DTiOx electrode, emphasizing the crucial role of the exposed basal plane in 2DTiOx as an efficient atomic scale Li+ flux regulator. This strategy is expected to advance next-generation lithium metal batteries (LMBs) by highlighting the significance of Li+ affinity at the Ti sites of 2DTiOx nanosheets.