Key Takeaways & Executive Findings
- •• Gas generation in sodium-ion batteries originates from cathode instability, electrode-electrolyte side reactions, and electrolyte decomposition, producing CO2, H2, and O2. • Mitigation strategies include electrolyte design, buffer layer construction, and electrode material optimization to enhance safety. • Long-term high-precision gas detection is crucial for improving SIB safety and performance. • SIBs are promising for large-scale energy storage and electric vehicles due to cost-effectiveness and abundant sodium resources.
Abstract
The transition to renewable energy sources has elevated the importance of SIBs (SIBs) as cost-effective alternatives to lithium-ion batteries (LIBs) for large-scale energy storage. This review examines the mechanisms of gas generation in SIBs, identifying sources from cathode materials, anode materials, and electrolytes, which pose safety risks like swelling, leakage, and explosions. Gases such as CO2, H2, and O2 primarily arise from the instability of cathode materials, side reactions between electrode and electrolyte, and electrolyte decomposition under high temperatures or voltages. Enhanced mitigation strategies, encompassing electrolyte design, buffer layer construction, and electrode material optimization, are deliberated upon. Accordingly, subsequent research endeavors should prioritize long-term high-precision gas detection to bolster the safety and performance of SIBs, thereby fortifying their commercial viability and furnishing dependable solutions for large-scale energy storage and electric vehicles.
1. Introduction
The transition of energy structures from traditional fossil energy to renewable energy is of immense significance for all of human society. Secondary batteries, characterized by their high energy density and long cycle life, have emerged as the most effective technology for energy storage. Among these, LIBs represent the leading electrochemical energy storage technology and have been successfully penetrated the market [1–4]. Their importance has been further emphasized by being awarded the Nobel Prize awarded in 2019 [4–9]. However, the widespread application of LIBs in large-scale energy storage systems faces challenges due to limited reserves of lithium resources and the high cost of lithium materials.
In contrast, sodium possesses abundant reserves and is cost-effective with characteristics similar to lithium [10, 11]. Therefore, SIBs are considered as one of the most promising candidates to replace part of current commercial LIBs, particularly for high-power and low-temperature applications. There are some differences in the gas production behavior of sodium and lithium batteries. First of all, the gas production of sodium battery mainly comes from the instability of cathode material, the side reaction between electrode and electrolyte, and the decomposition of electrolyte under high temperature or high voltage, which produces gases including CO2, H2, and O2. For example, Prussian blue cathode materials in sodium batteries induce the decomposition of solvents and salts in the electrolyte under high voltage to produce gas. The gas production in lithium batteries, on the other hand, is more related to the decomposition of the electrolyte, especially under extreme conditions such as overcharging, overheating, or short-circuiting, where the solvents and additives in the electrolyte decompose to produce a large amount of combustible gases, such as CO2, C2H4, and C2H6. In addition, the anode electrode material (e.g., silicon anode electrode) in lithium batteries also undergoes volume changes during the charging and discharging process, resulting in the decomposition of the electrolyte to produce gas. Overall, the gas generation mechanism of sodium batteries is relatively complex, involving a variety of materials and reaction pathways, while the gas generation of lithium batteries is more focused on the decomposition of the electrolyte.
Currently, the primary focus of competition in SIB research lies in achieving higher energy density with stable cycling performance [10, 12–16]. However, the enhancement of energy density is inevitably associated with the utilization of capacity in the high-voltage region. This leads to increased reactivity of the oxygen atoms within the material matrix, as well as more intense interfacial reactions between high-valent transition metals and t
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Xingyan Li, Xi Chen, Meng Li, Haoran Wei, Xuming Yang, Shenghua Ye, Liewu Li, Jing Chen, Xiangzhong Ren, Xiaoping Ouyang, Jianhong Liu, Xiangtong Meng, Jieshan Qiu, Biwei Xiao, Qianling Zhang, Jiangtao Hu (2025). Mechanisms and Mitigation Strategies of Gas Generation in Sodium-Ion Batteries. Nano-Micro Letters. https://doi.org/10.1007/s40820-025-01697-1
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Frequently Asked Questions
What are the main sources of gas generation in sodium-ion batteries?
Gas generation in sodium-ion batteries primarily arises from cathode material instability, side reactions between electrodes and electrolyte, and electrolyte decomposition under high temperatures or voltages, producing gases like CO2, H2, and O2.
How can gas generation in sodium-ion batteries be mitigated?
Mitigation strategies include designing more stable electrolytes, constructing buffer layers to suppress side reactions, and optimizing electrode materials to reduce gas-producing reactions.
Why is gas generation a safety concern in sodium-ion batteries?
Gas generation can lead to battery swelling, leakage, and even explosions, posing significant safety risks, especially in large-scale energy storage and electric vehicle applications.
What is the future research direction for improving sodium-ion battery safety?
Future research should focus on long-term high-precision gas detection to better understand and monitor gas evolution, thereby enhancing the safety and performance of sodium-ion batteries.
How do sodium-ion batteries compare to lithium-ion batteries in terms of gas generation?
Sodium-ion batteries exhibit more complex gas generation mechanisms involving multiple materials and pathways, while lithium-ion batteries primarily generate gas from electrolyte decomposition under extreme conditions.
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