Chinese researchers have introduced a groundbreaking sodium metal battery (SMB) design capable of achieving a full charge in just four minutes, with longevity that lasts for years. This innovation offers a substantial improvement over traditional lithium-ion (Li-ion) batteries, which rely on limited geographical resources and pose fire hazards.
Unlike sodium ion (Na ion) batteries, which use graphite or hard carbon anodes, SMBs employ a metallic sodium anode. This unique feature enhances battery performance while providing a potentially more affordable alternative.
However, SMB technology has faced challenges mainly due to dendrite formation. This phenomenon occurs when sodium ions accumulate irregularly on the highly reactive sodium anode, which can eventually create a bridge that short-circuits the battery.
Dendrite formation is particularly prevalent in sodium-based batteries due to sodium’s reactive properties. When charging, sodium ions interact with the electrolyte, forming a protective oxide layer known as the solid electrolyte interphase (SEI). As small as a virus — but effective. In sodium applications, this layer may crack, attracting ions and exacerbating dendrite formation.
To tackle this issue, researchers have implemented a robust quasi-solid gel electrolyte named Sn-FB QSE. This innovative structure not only reinforces the battery against punctures but also inhibits dendrite development. The findings were published on May 21 in the journal Science.
In tests, scientists successfully charged and discharged the battery for over 6,000 hours without issues from dendrite formation. The battery achieved a rapid zero to 100% charge in just four minutes, maintaining a capacity of 80.1 mAh g–1, roughly half that of conventional lithium-ion batteries.
At a slower charging rate, spanning 20 minutes from zero to 100%, the battery preserved 90% of its capacity over 2,000 cycles, indicating a promising future for SMB technology. Theoretical limits of lithium-ion batteries, the study states.
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This achievement is significant, particularly as it aims to charge faster than existing lithium-ion options. Charging speed remains critical for electric vehicles (EVs). The fastest charging EV to date is the BYD Denza, which can charge from 10 to 70% in only five minutes, but this requires a specialized 1MW charger.
In comparison, most electric vehicles have slower charge times. Tesla claims the Model 3 can charge from 10 to 70% in about 15 minutes using its proprietary 250kW flash charger, yet according to Zapmap, charging to 80% on a 50kW charger can take up to 90 minutes.
Currently, most batteries in smartphones and EVs are lithium-ion, which consist of lithium and cobalt—metals that are scarce and flammable, driving up production costs.
The battery sector is increasingly interested in the commercial viability of cost-effective and safe sodium ion batteries, but these tend to be heavier than their lithium-ion counterparts.
Sodium metal batteries present an exciting alternative as they merge the advantages of both battery types. They promise comparable dimensions and weight to lithium-ion while using sodium anodes, thus leading to lower manufacturing costs. Additionally, their operation using sodium ions minimizes the risk of thermal runaway—a concern in damaged batteries.
With advancements to address dendrite formation and improve low-temperature stability, small and medium enterprises could revolutionize battery deployment economics within the next decade, as researchers anticipate.
Although SMBs currently have a limited range compared to Na-ion and Li-ion vehicles, their rapid charging potential makes them an ideal candidate for public transit and commuter vehicles. However, they may not be suitable for small devices like smartphones and consumer electronics in the near future.
Smartphones undergo significant temperature fluctuations that can impact the chemistry of batteries that utilize gel electrolytes. Further studies need completion before manufacturers can confidently transition to using pure sodium metal instead of the well-established graphite structure.
Source: www.livescience.com