Homogenizing Li₂CO₃ Nucleation and Growth through High-Density Single-Atomic Ru Loading toward Reversible Li-CO₂ Reaction

Abstract

The high activation barrier and sluggish kinetics of Li2CO3 decomposition impose a severe challenge on the development of a Li-CO2 battery with high Coulombic efficiency. To tackle this issue, herein we devise a novel synthetic tactic by combining electrostatic assembly with in situ polycondensation to obtain a single-atomic Ru catalyst of high density up to ∼5 wt %. When deployed to the CO2 cathode, the catalyst delivered an extraordinary capacity of 44.7 Ah g–1, an ultralow charge/discharge polarization of 0.97 V at 0.1 A g–1 (1.90 V at 2 A g–1), and a long-term cycling stability up to 367 cycles at 1 Ah g–1 (196 cycles at 2 Ah g–1), outshining most of the state-of-the-art CO2 cathode catalysts reported today. Further through extensive in situ and ex situ electroanalytical, spectroscopic, and microscopic characterizations, we attribute the superb battery performance mainly to the highly reversible Li2CO3 formation/decomposition, facilitated by the homogenized and downsized Li2CO3 nucleation and growth on account of the high density single-atomic Ru loading. This work not only offers a facile method to fabricate single-atom catalysts with high mass loading but also sheds light on promoting the reversible Li-CO2 reaction by mediating product morphology.

Recent progress on single-atom catalysts for lithium–air battery applications

“…Further efforts were devoted to investigating the catalytic activity of Ru SACs in LCBs, and these studies also confirmed the superior battery performance of SACs compared with that of nanoparticles. 50,191…”

“…Recently, single-atom catalysts (SACs) with fully exposed atom surfaces and extremely high catalytic activity were introduced into LABs, serving as a powerful strategy in boosting the formation/decomposition process of discharge products and taming the bothersome lithium dendrite with significant enhancement in the battery performance, such as reduced overpotential, improved security, increased capacity and enhanced cyclability 22,[42][43][44][45][46][47][48][49][50][51][52][53][54] (Fig. 1).…”

Recent progress of transition metal-based catalysts as cathodes in O2/H2O-involved and pure Li–CO2batteries

“…In 2020, Baek et al adopted Ru nanoparticles as the cathode and a nitrate-based molten salt as the electrolyte to explore the role of NO 2 À in the decomposition mechanism of surface , as shown in eqn (35).…”

“…34 However, although noble metal catalysts exhibit excellent electrochemical activity and catalytic stability, their high price, chemical vulnerability and low reserves limit their large-scale applications. 35 Alternatively, carbon-based catalysts have attractive advantages such as low cost, high abundance, and tunable morphology and structure, but their unsatisfactory catalytic activity and stability limit their development. 36 Therefore, researchers are devoted to selecting and optimizing abundant, highly active, and durable transition metal catalysts to enhance the catalytic performance of Li–CO 2 batteries.…”

Metal-related electrocatalysts for Li–CO2batteries: an overview of the fundamentals to explore future-oriented strategies

“…As a rising star, single-atom catalysts (SACs) are also of interest to researchers in the field of Li–CO 2 batteries. 177–180 The main reasons are: (1) the isolated metal sites have nearly 100% atomic utilization; (2) SACs have fully exposed active sites. These two points together determine the outstanding catalytic activity of SACs.…”