Introduction
Lithium-ion batteries have been dominating the electric vehicle market, but there’s a new contender in town – sodium-ion batteries. The excitement surrounding sodium-ion batteries is immense, but it can be challenging to determine if they are truly a step towards a sustainable future or just hype. Fortunately, sodium-ion cells have been quickly commercialized, making them accessible to regular consumers. In this article, we explore the performance of sodium-ion batteries compared to lithium-ion packs, using them in a DIY battery pack for a small vehicle.
Testing the Packs
To conduct a fair comparison between sodium-ion and lithium-ion cells, the author decided to create their own battery packs. These packs were designed to accept 18650-type cells, which are widely available in the market and can provide sufficient voltage for the vehicle. The author’s experiment involved using 12 separate cell holders connected by copper traces and components pre-soldered on a circuit board. The packs were charged and discharged through a common XT60-type connector, suitable for the application.
Comparing the Cells
The author purchased both sodium-ion and lithium-ion cells for the comparison. The sodium-ion cells were easily sourced from a reseller and came with an adequate datasheet. These cells were rated at 1.3Ah with a nominal voltage of 3.0V, offering 3.9 watt-hours of energy. On the other hand, the lithium-ion cells had a capacity of 2.5Ah with a nominal voltage of 3.6V, providing 9 watt-hours of energy per cell. Despite the higher capacity of lithium cells, sodium cells were significantly cheaper, costing $1.52 each compared to $4-$6 for lithium cells.
Running the Packs
Capacity is an essential factor in batteries, but specific power is equally crucial. The sodium-ion cells had a lower capacity compared to lithium-ion cells but could deliver a comparable power output. When combined into packs, the lithium pack contained 108Wh of energy and could provide 864W continuously, while the sodium pack had 46.8Wh and could output 468W. The lithium pack offered faster acceleration and charging capabilities compared to the sodium pack, highlighting the trade-offs between energy density and price.
The Reality of Sodium-Ion
Sodium-ion batteries offer a cost-effective solution with good cycle life, lasting up to 3,000 cycles before significant degradation. While sodium-ion cells currently lack the energy density of lithium-ion cells, they could be well-suited for hybrid cars or grid storage applications where cycle life and power density are crucial factors. Despite the lower energy density, sodium-ion batteries present a significant cost advantage, making them a viable option for certain applications. In the author’s experiment, a sodium-ion battery pack cost just $18.24, significantly less than the stock battery for the vehicle.
Conclusion
In conclusion, sodium-ion batteries show promise as a cost-effective alternative to lithium-ion batteries, particularly for applications where cycle life and power density are essential. While sodium-ion cells currently fall short in energy density compared to lithium-ion cells, ongoing developments could improve their performance in transportation contexts. The author’s experiment with sodium-ion batteries highlights the trade-offs in energy density, power output, and price, showcasing the potential of sodium-ion technology in the evolving landscape of energy storage solutions.