Scientists from China have announced a significant breakthrough in the field of batteries, developing a metallic sodium battery capable of reaching a full charge in just four minutes. This new system demonstrated robust stability when subjected to thousands of hours of testing. The findings were formally published this May in the scientific journal Nano-Micro Letters.
The central objective of this innovation is to overcome one of the main obstacles inherent to this type of battery: the formation of dendrites. These are microstructures that can cause short circuits and consequently drastically reduce cell durability. To mitigate this issue, the research team created a semi-solid gel electrolyte.
If the results obtained can be replicated on an industrial scale, this technology has the potential to expand the options available compared to lithium-ion batteries, especially in the electric vehicle sector. This is due both to the potentially lower cost of sodium and the significantly reduced charging time.
Metallic sodium batteries are seen as a very promising alternative to current technologies because they use a more accessible and less expensive material compared to lithium. Additionally, experts indicate that this battery model has a lower fire risk than conventional lithium-ion based systems.
Historically, the commercial advancement of these batteries faced a major impediment: during charging cycles, sodium atoms tend to deposit onto the metallic anode, forming so-called dendrites. Over time, these structures grow until they make contact between the internal electrodes, resulting in a short circuit and battery failure.
To combat this challenge, the researchers created a quasi-solid electrolyte, named Sn-FB QSE. According to the study, this material establishes a more resilient internal architecture, minimizes cracks in the protective layer that naturally forms during battery use, and hinders the appearance of dendrites.
Tests conducted in the laboratory showed that the battery operated for over six thousand hours of charge and discharge cycles without suffering short circuits caused by such structures. In another test, the device was fully charged in four minutes, exhibiting a specific capacity of 80.1 milliampere-hours per gram.
The data presented by the authors reveals that when the recharging period was extended to twenty minutes, the battery maintained about 90% of its capacity after two thousand complete cycles. This performance approaches what is theoretically expected of lithium-ion batteries, but with the clear advantage of a faster charging process.
Fast charging is a crucial factor for the expansion of electric vehicles. While some current models already offer fast charging, they require high-power infrastructure. On the other hand, much of the electric car fleet still requires considerably longer recharging intervals. Researchers also point out that lithium-ion batteries remain predominant in smartphones, computers, and electric vehicles, but they depend on raw materials like lithium and cobalt, whose acquisition is more costly. Furthermore, this type of battery is more prone to thermal runaway, which causes fires in case of damage.
Metallic sodium batteries aim to combine the positive qualities of traditional sodium batteries and lithium-ion batteries. By employing metallic sodium in the anode, instead of graphite or hard carbon, they can offer lower weight and reduced costs while maintaining the safety levels associated with handling sodium ions. However, the research emphasizes that important challenges remain before the commercial implementation of the technology. The scientists state that it is essential to confirm the reproducibility of the experiments and evaluate their performance under various temperatures, a vital condition for automotive and electronic equipment applications.
Researchers at the University of Michigan have developed a new methodology to optimize the battery management of electric vehicles. This study, published in the journal Joule, focuses on lithium batteries that use a combination of silicon and graphite, aiming to extend their longevity through dynamic thermal adjustments.
The proposed system integrates into the vehicle itself and has the ability to analyze the charge data naturally generated during use. Based on this information, it can precisely identify the moments when the silicon in the battery cells is most susceptible to wear. By making this reading, the system intervenes dynamically, regulating the battery temperature according to the behavior of the internal components, heating or cooling the unit according to the most active material, which minimizes wear over time.
This project received support from General Motors and Imperial College London, in addition to funding from the National Science Foundation. The results point to significant potential for increasing the durability of batteries used in electric cars.
The research starts from the fact that modern batteries combine graphite and silicon, with the latter being a material capable of retaining approximately ten times more lithium. However, silicon shows greater fragility during charging and discharging processes. Zhiwen Wan, the doctoral student responsible for the investigation, emphasized that progress depends on the union between the material and operational control, stating that advanced materials will only reach their maximum potential if they are intelligently managed after being integrated into real products.
The investigation revealed that the point of action of silicon is not constant; it fluctuates depending on how the vehicle is used, potentially varying between 33% and 73% of the charge level, which modifies the ideal management strategy. Anna Stefanopoulou, senior co-author, clarified that current systems usually operate with fixed parameters, but their work paves the way for active diagnostic management systems.
Tests also showed that silicon can undergo expansions of up to 300% in full charge cycles, leading to the formation of fissures and loss of active material over time. Furthermore, the scientists noted that temperature affects aging in distinct ways: heat aids performance during active use, while high temperatures at rest accelerate internal deterioration. Jason Siegel, an involved engineer, stressed the importance of selective control, as temperature must be applied in a targeted manner.
The suggested mechanism uses this behavior to heat the battery when the silicon is most active and cool it when the graphite dominates or when the car is parked. This tactic is specifically limited to slow charging situations, such as those performed using home outlets or low-capacity public points.
