Achieving 480 Wh kg⁻1 in 4.6 V Lithium Metal Batteries with Ultrahigh-Nickel Cathodes via a Multifunctional Additive

Abstract

High-nickel layered oxides (e.g., LiNi_0.90Co_0.05Mn_0.05O₂, NCM9055) coupled with lithium metal anodes are promising for next-generation high-energy-density batteries, yet their practical implementation is hindered by critical interfacial instabilities, including lithium dendrite growth, electrolyte decomposition at high voltages (≥ 4.5 V vs. Li/Li⁺), and transition metal dissolution. To address these concurrent challenges, we introduce 2-propoxy-5-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)pyridine (PTDP) as a novel multifunctional electrolyte additive designed for dual-electrode stabilization. The innovative molecular architecture of PTDP integrates a pyridine ring, which chelates transition metals to inhibit dissolution, with a boronic ester group functioning as an anion receptor to enhance Li⁺ transport and homogenize flux. Density functional theory calculations reveal that PTDP preferentially decomposes to form a robust LiF/Li₃N/LiBO₂ hybrid interphase exhibits an exceptionally high Li⁺ adsorption energy (–6.70 eV), facilitating uniform Li⁺ deposition, accelerated kinetics, and effective dendrite suppression. Concurrently, the PTDP-derived cathode electrolyte interphase preserves the structural integrity of the NCM9055 cathode during cycling. As a result, a 1.5 Ah NCM9055||Li pouch cell employing a carbonate-based electrolyte with only 0.5 wt% PTDP additive demonstrates exceptional cycling stability, retaining 95.8% of its capacity after 60 cycles at 4.6 V, and delivering a high energy density of 480 Wh kg⁻¹, significantly outperforming additive-free counterpart.