The transition to a low-carbon future hinges on our ability to store and deliver green energy efficiently. As electrification grows across industries, from transportation to grid storage, there is an urgent need for high-performance batteries that offer greater capacity and efficiency and a longer lifespan. More on new structural batteries for the transportation industry in our recent article: 

Ultralight Carbon Fibre Structural Battery

As the demand for such high-performance energy storage solutions continues to surge, advanced battery technologies such as lithium-ion (Li-Ion) with silicon anodes, lithium-sulphur (Li-S), and sodium-ion (Na-Ion) batteries have gained significant attention. While these technologies present unique advantages, they also face critical hurdles that hinder their commercialisation. Carbon nanotubes (CNTs) have emerged as a promising material to address these challenges and drive improvements in battery performance, as evidenced by recent news about the first-ever commercial-scale battery-grade CNT facility in the US (read more below!). 

First-Ever Commercial-Scale Battery-Grade CNT Facility to Open in the US 

CNT Applications in Silicon Anode Li-Ion Batteries

Silicon anodes offer a theoretical capacity (~3579 mAh/g) far exceeding that of conventional graphite anodes (~372 mAh/g). However, their practical use is limited by severe volumetric expansion up to 300%, leading to mechanical degradation and loss of electrical connectivity. CNTs provide a solution by forming flexible conductive networks that buffer silicon’s expansion, maintaining the electrode’s structural integrity over repeated cycles. 

Beyond volume expansion, CNTs’ high electrical conductivity enhances electron transport and anode integrity, ensuring efficient charge transfer and improving cycling performance. Additionally, their mechanical resilience helps mitigate silicon fracturing and capacity loss, a key limitation of silicon anodes. CNTs also facilitate Li-Ion diffusion, improving ion transport pathways and contributing to overall electrode stability.

CNT Applications in Li-S Batteries

Li-S batteries are an attractive option due to their high theoretical energy density (~2600 Wh/kg) and the planetary abundance of sulphur. However, they suffer from issues such as the polysulphide shuttle effect, poor electronic conductivity, and rapid capacity fading. CNTs serve as an effective sulphur host, enabling strong polysulphide adsorption, thereby suppressing polysulphide dissolution and significantly improving material stability. 

Additionally, CNTs enhance sulphur utilisation by forming a highly conductive network that reduces internal resistance and facilitates charge transport. Their structural properties contribute to improved Li-S reaction kinetics, ensuring more efficient electrochemical performance. By mitigating the polysulphide shuttle effect and reducing resistance, CNTs help extend cycling performance, making Li-S batteries more viable for long-term use. 

Recently, researchers at the Korea Electrotechnology Research Institute (KERI) Next Generation Battery Research Center developed a new battery design, using single-walled CNTs, to overcome the polysulphide shuttle effect. Check out the full story below. 

A Promising Approach to Ultra-Flexible 1 Ah Lithium–Sulphur Batteries Using Oxygen-Functionalized Single-Walled Carbon Nanotubes

CNT Applications in Na-Ion Batteries

Owing to sodium’s natural abundance, Na-Ion batteries present a lower-cost alternative to Li-Ion. However, they face challenges such as the large Na-Ion radius, which leads to structural instability, poor rate capability, and lower energy density. 

CNTs enhance the mechanical stability of anode and cathode materials, preventing electrode degradation over time. Additionally, CNTs significantly increase electron transport, improving overall conductivity within Na-Ion cathodes. By improving Na-Ion diffusion rates, CNTs enable better charge-discharge efficiency, boosting the battery’s performance and durability.

Comparative Analysis of CNT Benefits Across Battery Types

The table below summarises the key hurdles of each battery type and how CNTs could help overcome them:

Conclusion

CNTs are proving to be a game-changing material across various battery chemistries. By addressing key technical challenges in silicon anode Li-Ion, Li-S, and Na-Ion batteries, CNTs are driving the next generation of high-energy, long-lasting, and commercially viable battery technologies. 

Recent research efforts have demonstrated the impressive energy storage capacity of CNTs. We’ve also seen how critical their configuration is in enhancing device performance. Learn more in our recent articles: 

Unlocking the Energy Revolution with Twisted Carbon Nanotubes

Carbon Nanotubes in Battery Technology: Opportunities and Emerging Solutions

As research and development efforts continue, further integration of CNTs into these systems will accelerate the transition toward superior energy storage solutions, with the potential to drive us toward a more sustainable, carbon-neutral future.