Opportunities and Challenges in the Development of Layered Positive Electrode Materials for High-Energy Sodium Ion Batteries: A Computational Perspective

Abstract

In recent years, high-energy-density sodium ion batteries (SIBs) have attracted enormous attention as a potential replacement for LIBs due to the chemical similarity between Li and Na, high natural abundance, and low cost of Na. Despite the promise of high energy, SIBs with layered cathode materials face several challenges including irreversible capacity loss, voltage hysteresis, voltage decay, irreversible TM migrations that lead to fast capacity fading, and structural degradation. However, their electrochemical performance can be improved by introducing reversible anionic redox along with conventional cationic redox. This Perspective systematically summarizes different factors that trigger the irreversible anionic redox in Na-based cathode materials. Additionally, this Perspective highlights the mechanistic understanding and key challenges for reversible anionic redox and proposes plausible solutions to overcome these limitations. The overview of various existing experimental and theoretical approaches presented here could provide a futuristic pathway to design Nabased cathode materials for high-energy-density SIBs.

Stabilizing Anionic Redox and Tuning Its Extent in Na-Rich Cathode Materials through Electronic Structure Engineering

“…Currently, lithium-ion batteries (LIBs) play a pivotal role in powering a wide array of devices and hold a dominant position in the global energy storage market for electric vehicles (EVs). − However, the surging demand for large-scale energy storage solutions, coupled with the limited availability of lithium reserves and the high cost associated with lithium-based materials, underscores the necessity to explore alternative battery chemistries. − In this regard, sodium-ion batteries (SIBs) have emerged as a promising alternative to LIBs due to the abundant and cost-effective nature of sodium. − Despite the significant attention garnered by SIBs, their practical application for high-capacity purposes remains hampered by the relatively low specific capacity of sodium-based cathode materials. − Efforts to unlock additional capacity from sodium-rich/deficient cathodes in SIBs have introduced the concept of anionic redox chemistry alongside conventional cationic redox, offering a promising route to enhance capacity. ,− However, the utilization of anionic redox can be plagued by issues such as overoxidation of lattice oxygen, resulting in the release of molecular O 2 and structural destabilization, leading to voltage hysteresis. , In this regard, Zhang et al adapted the strategy of surface coating and rare-earth metal doping to achieve reversible anionic redox and stable phase transition during the redox process . They utilized a P2-Na 0.67 Mn 0.7 Ni 0.2 Co 0.1 O 2 cathode material coated with CeO 2 to demonstrate the effect of surface coating on the structural and electrochemical performance of Na-ion batteries experimentally and theoretically .…”

In-Situ Polymerized Solid-State Polymer Electrolytes for High-Safety Sodium Metal Batteries: Progress and Perspectives

“…In the last, SIBs usually possess a longer service life, higher rate performance, and wider operating temperature range compared with LIBs [1][2][3]. With the rapid growth of plug-in or hybrid electric vehicles and largeformat green energy storage power stations, high-energy and high-safety SIBs are urgently desired [4][5][6]. To remarkably improve the energy density of SIBs, significant research efforts have been dedicated to finding and identifying suitable electrode materials and several promising types of cathodes (e.g., layered transition metal oxides, sodium fluorophosphates, etc.)…”