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 (2DTiO<i>x</i>) 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|2DTiO<i>x</i>|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 2DTiO<i>x</i>-based symmetric cell containing a limited Li amount from electrodeposited Li metal (e-Li|2DTiO<i>x</i>|e-Li). The full cells (e-Li|2DTiO<i>x</i>||NCM811 and e-Li|2DTiO<i>x</i>||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 2DTiO<i>x</i> electrode, emphasizing the crucial role of the exposed basal plane in 2DTiO<i>x</i> 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 2DTiO<i>x</i> nanosheets.