Impact of a Gold Nanocolloid Electrolyte on Li2O2 Morphology and Performance of a Lithium-Oxygen Battery

Critical Effects of Insoluble Additives in Liquid Electrolytes for Metal Batteries

Rechargeable metal batteries have received widespread attention due to their high energy density by using pure metal as the anode. However, there are still many fundamental problems that need to be solved before approaching practical applications. The critical ones are low charge/discharge current due to slow ion transport, short cycle lifetime due to poor anode/cathode stability, and unsatisfied battery safety. To tackle these problems, various strategies have been suggested. Among them, electrolyte additive is one of the most widely used strategies. Most of the additives currently studied are soluble, but their reliability is questionable, and they can easily affect the electrochemical process, causing unwanted battery performance decline. On the contrary, insoluble additives with excellent chemical stability, high mechanical strength, and dimensional tunability have attracted considerable research exploration recently. However, there is no timely review on insoluble additives in metal batteries yet. This review summarizes various functions of insoluble additives: ion transport modulation, metal anode protection, cathode amelioration, as well as battery safety enhancement. Future research directions and challenges for insoluble solid additives are also proposed. It is expected this review will stimulate inspiration and arouse extensive studies on further improvement in the overall performance of metal batteries.

Reducing Overpotential of Lithium-Oxygen Batteries by Diatomic Metal Catalyst Orbital Matching Strategy

Aprotic Li-O2 batteries have sparked attention in recent years due to their ultrahigh theoretical energy density. Nevertheless, their practical implementation is impeded by the sluggish reaction kinetics at the cathode. Comprehending the catalytic mechanisms is pivotal to developing efficient cathode catalysts for high-performance Li-O2 batteries. Herein, the intrinsic activity map of Li-O2 batteries is established based on the specific adsorption mode of O2 induced by diatomic catalyst orbital matching and the transfer-acceptance-backdonation mechanism, and the four-step screening strategy based on the intrinsic activity map is proposed. Guided by the strategy, FeNi@NC and FeCu@NC promising durable stability with a low overpotential are screened out from 27 Fe-Metal diatomic catalysts. Our research not only provides insights into the fundamental understanding of the reaction mechanism of Li-O2 batteries but also accelerates the rational design of efficient Li-O2 batteries based on the structure-activity relationship.

Tailoring the p-Band Center of NS Pair for Accelerating High-Performance Lithium-Oxygen Battery

The local coordination environment of catalytical moieties directly determines the performance of electrochemical energy storage and conversion devices, such as Li-O₂ batteries (LOBs) cathode. However, understanding how the coordinative structure affects the performance, especially for non-metal system, is still insufficient. Herein, a strategy that introduces S-anion to tailor the electronic structure of nitrogen-carbon catalyst (SNC) is proposed to improve the LOBs performance. This study unveils that the introduced S-anion effectively manipulates the p-band center of pyridinic-N moiety, substantially reducing the battery overpotential by accelerating the generation and decomposition of intermediate products Li_1-3 O₄ . The lower adsorption energy of discharging product Li₂ O₂ on NS pair accounts for the long-term cyclic stability by exposing the high active area under operation condition. This work demonstrates an encouraging strategy to enhance LOBs performance by modulating the p-band center on non-metal active sites.

Enhanced catalytic performance of pillared δ-MnO2 with enlarged layer spaces for lithium- and sodium-oxygen batteries: a theoretical investigation

Facing the challenge of increasingly severe environmental issues, many researchers are committed to seeking "post lithium-ion batteries" that can replace fossil fuels, one of which is alkali-metal-oxygen batteries. Nevertheless, the main bottleneck restricting the development of these batteries is the need for suitable catalysts to facilitate the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). In this study, we attempt to modify the catalytic performance of δ-MnO₂ for lithium- and sodium-oxygen batteries (LOBs and SOBs) by constructing 1,4-benzenedisulfonic acid, 2-chloro-1,4-benzenedisulfonic acid, and 2-fluoro-1,4-benzenedisulfonic acid pillared structures (H-, Cl-, and F-MnO₂). Their dynamic stability and catalytic mechanism have been explored by employing density functional theory (DFT). H-MnO₂ possesses a theoretical discharge voltage of 2.645 V for LOBs, which is 0.293 V larger than that of Cl-MnO₂. The discharge voltage of Cl-MnO₂ for SOBs is 3.152 V; however, H-MnO₂ impedes the formation of sodium superoxide and can hardly promote the ORR in SOBs. Both H- and Cl-MnO₂ can prevent the parasitic disproportionation reaction in LOBs and SOBs that produce active singlet oxygen through different reaction mechanisms. We believe that the constructed pillared structures are efficient ORR/OER catalysts for alkali-metal-oxygen batteries. Our research provides a theoretical basis for the micro-level mechanism of LOBs and SOBs catalyzed by the pillared δ-MnO₂ and sheds light on ameliorating the properties of the catalyst by constructing pillared structures.