The main problems and solutions in practical application of anode materials for sodium ion batteries and the latest research progress

Abstract

Summary Lithium‐ion batteries(LIBs) have been widely used in people's daily lives. At the same time, in the face of the growing demand for LIBs, the minable lithium mines on the earth are facing resource exhaustion. From the perspective of sustainable development, it is inevitable to seek new batteries. Sodium‐ion batteries(SIBs) are attracting attention due to their rich resources and low cost, and are expected to be used in large‐scale energy storage. In recent years, anode materials have made a lot of important progress as the key elements of SIBs. The research of anode materials is mainly concentrated on carbon‐based materials, titanium‐based materials, alloying materials, conversion materials, and organic materials. However, due to the large sodium ion radius, the large volume change of materials, and slow kinetics, the electrochemical performance of the materials is poor. This article systematically summarizes the latest research progress of these types of anode materials and discusses the main existing problems and the solution strategy and the prospect of the development of negative electrode materials.

Recent Advances in Carbon Anodes for Sodium‐Ion Batteries

“…Depending on the type of the positive and negative electrode materials, the Na storage mechanism can be different. Considering a layered NaMO 2 (M=transition metal) as a positive electrode and a carbon‐based material as a negative electrode, redox reactions of a SIB can be generally written as: [19] $$$\vcenter{\openup.5em\halign{$\displaystyle{#}$\cr NaM{O}_{2}{\stackrel{ {\rightarrow} } { {\leftarrow} } } {Na}_{1-x}{MO}_{2}+x{Na}^{+}+x{e}^{-}\hfill\cr}}$$$ $$$\vcenter{\openup.5em\halign{$\displaystyle{#}$\cr C+x{Na}^{+}+x{e}^{-}{\stackrel{ {\rightarrow} } { {\leftarrow} } } {Na}_{x}C\hfill\cr}}$$$ $$$\vcenter{\openup.5em\halign{$\displaystyle{#}$\cr NaM{O}_{2}+C{\stackrel{ {\rightarrow} } { {\leftarrow} } } {{Na}_{1-x}{MO}_{2}+Na}_{x}C{\rm \ }(0\le x\le 1)\hfill\cr}}$$$ …”

“…However, there are fundamental differences between the two alkali metal ions as summarized in Table 1. For example, the standard reduction potential of Na + /Na (−2.71 V) is less negative than that of Li + /Li (−3.04 V), so the operating voltage window of SIBs is lower than that of LIBs, thus, the electrolyte is less likely to decompose [19–24] . This boosts the safety and long‐term stability of the battery.…”

“…For example, the standard reduction potential of Na + /Na (À 2.71 V) is less negative than that of Li + /Li (À 3.04 V), so the operating voltage window of SIBs is lower than that of LIBs, thus, the electrolyte is less likely to decompose. [19][20][21][22][23][24] This boosts the safety and long-term stability of the battery. Moreover, unlike Li ions that form an alloy with Al, [25][26][27][28] Na ions are non-reactive with Al.…”

Review on recent progress in Manganese‐based anode materials for sodium‐ion batteries

“…Ether-based electrolytes have been widely reported to be more compatible for Naion batteries because the electrolyte could help to form a stable structure and also reversibility of the Na-ion insertion/extraction. 108 It is worth to explore this type of electrolyte for Mn-based anode materials since no much studies have been reported so far. In addition, systematic comparison between the electrochemical performances of the Mn-based anode materials with/without the FEC as an additive should be conducted.…”

“…Suitable electrolytes play an essential role in improving the Na storage properties of the anodes. Ether‐based electrolytes have been widely reported to be more compatible for Na‐ion batteries because the electrolyte could help to form a stable structure and also reversibility of the Na‐ion insertion/extraction 108 . It is worth to explore this type of electrolyte for Mn‐based anode materials since no much studies have been reported so far.…”