Manganese‐Based Na‐Rich Materials Boost Anionic Redox in High‐Performance Layered Cathodes for Sodium‐Ion Batteries

Abstract

of the most attractive inventions because they have dramatically improved our daily lives by enabling portable electronics, the onset of electronic mobility and electrical vehicles. [1] With the development of materials science, anionic redox chemistry, typically O redox, has enabled more energy storage than the traditional electrochemical reactions, in which the energy and power density are solely determined by the cation redox reaction of transition metals. [2] On the other hand, the rapid growth of lithium consumption leads to continuously increasing demand for lithium. Considering the uneven distribution of lithium resources, the inherent drawbacks of lithium supply and demand are difficult to overcome. [3] Therefore, an alternative to lithium must be considered, especially for large-scale energy storage applications in the foreseeable future.The Na-ion battery, which has a reaction pattern comparable with that of the Li-ion battery, is one of the promising alternatives because of its low cost and the abundance of sodium resources. [4] Currently, the study of Na-ion batteries is focused on improving their energy density. Considering the successful study of Lirich materials, one of the possible solutions to improve the capacity of Na-ion batteries is to develop Na-rich materials. It is very important to involve reversible O redox and expand the material series from the material design point of view.Recent research disclosed, the increasing of the Li(Na) content within layered structure materials can effectively influence the local atom coordination around oxygen atoms which could improve O redox upon cycling and lead to a higher capacity. [5] As demonstrated by Tarascon and Ceder et al., increasing the Li(Na) ratio can shift the O 2p nonbonding band gradually up near the Fermi level. This labile nonbonding O offers an extra way for electrons to move away, hence increasing the capacity by triggering an extra redox process. [2e,5c,6] This explanation has been successfully applied to Li 2 MnO 3 Li-rich materials [7] and is widely agreed upon. Benefitting from the established Li 2 MnO 3 Li-rich prototype, Li-rich material development has highly improved during the past decades, achieving additional capacity. [8] For the counterpart Na-ion battery design, although anionic redox was recently realized in the Mn-based To improve the energy and power density of Na-ion batteries, an increasing number of researchers have focused their attention on activation of the anionic redox process. Although several materials have been proposed, few studies have focused on the Na-rich materials compared with Li-rich materials. A key aspect is sufficient utilization of anionic species. Herein, a comprehensive study of Mn-based Na 1.2 Mn 0.4 Ir 0.4 O 2 (NMI) O3-type Na-rich materials is presented, which involves both cationic and anionic contributions during the redox process. The single-cation redox step relies on the Mn 3+ /Mn 4+ , whereas Ir atoms build a strong covalent bond with O and effectively suppress the O 2 release....

Quantification of Anionic Redox Chemistry in a Prototype Na-Rich Layered Oxide

“…[16][17][18][19] Inspired by this paradigm, great efforts have also been devoted to introducing anionic redox activity into Naion electrodes. [20][21] Most recently, Na3RuO4 was introduced as a pure prototype Na-rich layered oxide for SIBs, which delivers an outstanding electrochemical performance. [22][23] However, the charge compensation mechanism of Na3RuO4 undergoes different hypotheses: (i) Qiao et al…”

Deciphering an Abnormal Layered‐Tunnel Heterostructure Induced by Chemical Substitution for the Sodium Oxide Cathode

“…)f or SIBs have received significant attention because of the large theoretical specific capacity,low cost, and simple analogies from the successful application of LiMeO 2 in Li-ion battery systems. [4] However,conventional single-phase oxide cathodes commonly face the challenge of simultaneously achieving long cycle life and excellent rate performance while realizing high specific capacity. [5] Forinstance,although Mn-based tunnel structure Na 0.44 MnO 2 cathode material displays superior cycling stability and rate capability,t he specific capacity is insufficient to meet the energy storage need of the rapid development of modern society.…”

In-situ/operando characterization techniques in lithium-ion batteries and beyond

“…Similarly, in the research of LiNi 0.5 Mn 0.3 Co 0.2 O 2 cathode, the inhomogeneous SOC distribution was observed as well and the ''overdelithiation" in initial cycles could issue in the following capacity degradation [150]. In addition to detecting the SOC distribution, the variations of surficial bonding states could also be obtained by in-situ Raman, which attributed the mechanism exploration of complex systems [151,152]. Using in-situ Raman, the oxygen redox process was identified by the signals of O-O peroxo bond, demonstrating the origin of high capacity of Li-rich Li 1.2 Ni 0.2 Mn 0.6 O 2 cathode (Fig.…”