An initial look at the sodium ion battery pack based on what we know to date, who is about to launch products and how it compares to Lithium Ion. This will need to be extended as more information is released and hence we get a chance to do more calculations.
Sodium Ion Chemistry
Sodium-ion batteries operate analogously to lithium-ion batteries, with both chemistries relying on the intercalation of ions between host structures. In addition, sodium based cell construction is almost identical with those of the commercially widespread lithium-ion battery types. However, sodium-ion batteries are characterised by several fundamental differences with lithium-ion, bringing both advantages and disadvantages.
Up until recently the view was that Sodium Ion would replace Lithium Iron Phosphate as a low cost option for grid storage, server backup power and maybe for 12V. However, as with the BYD blade moving LFP back into the limelight, the Sodium Ion pack promises to reduce costs further and deliver a more sustainable chemistry.
At the moment though the cell specification data and test results are scarce, hence we are piecing together what we know of the sodium ion battery packs announced to date.
Announcements
The vehicle battery packs announced to date and what we know:
HiNa Battery and JAC Group
The VW joint venture with Anhui Jianghuai Automobile Group Corp. Ltd. (JAC) in China produces the E10X. They have used a Hina Sodium Ion battery pack to demonstrate the technology.
6 March 2023 – JAC Motors unveils world’s first sodium-ion battery vehicle – Sehol E10X Sodium Ion
HiNa Battery:
- Pack
- Energy = 25 kWh (claimed)
- 72Ah
- Pack nominal voltage = 341V
- Energy = 24.552kWh
- Configuration = 110s6p
- Mass = 205kg (based on energy and density)
- Gravimetric Energy Density = 120Wh/kg
- Cell to pack mass ratio = 82%
- Charging 10 to 80% = 20minutes
- Energy = 25 kWh (claimed)
Written based on the support and sponsorship of: AVANT Future Mobility, Quarto Technical Services, TAE Power Solutions, h.e.l group and The Limiting Factor.
BYD
The BYD Seagull is their third-generation EV platform and it will apparently be sold with two different electric motor and battery options in China [2].
BYD have developed the Sodium Ion chemistry, will make the cells and are also a vehicle manufacturer. Quite a unique position.
The image suggests that BYD are also developing a cylindrical sodium ion cell. At this point we don’t have enough information to put these together.
Chery and CATL
Chery will be the first automaker to use CATL’s sodium-ion batteries [4]. In 2021 CATL stated that their first generation of sodium ion cells would achieve 160Wh/kg, however, we haven’t seen a datasheet or better still an independent test.
Jiangling Motors and Farasis Energy
Jiangling Motors Electric Vehicle which is majority owned by Renault are planning to launch their EV3 with a Sodium Ion pack based on Farasis Energy cell.
References:
- Lina Zhao, Teng Zhang, Wei Li, Tao Li, Long Zhang, Xiaoguang Zhang, Zhiyi Wang, Engineering of sodium-ion batteries: Opportunities and challenges, Engineering, 2022, ISSN 2095-8099
- BYD’s Seagull Starts At Just $11,300 And Has Sodium-Ion Battery, CarScoops
- Sodium-ion batteries deployed in China with Renault partner, Electrive.com
- Chery becomes first customer for CATL’s sodium-ion batteries, electrive.com
Pack Sizing
The usable energy (kWh) of the pack is fundamentally determined by:
- Number of cells in series (S count)
- Number of cells in parallel (P count)
- Capacity of a single cell (Ah)
- Nominal voltage of a single cell (Vnom)
- Usable SoC window (%)
Energy (kWh) = S x P x Ah x Vnom x SoCusable / 1000
Note: this is an approximation as the nominal voltage is dependent on the usable window. Also, the variation in cell capacity will be needed to be understood to establish accurate pack capacity values in production. However, all of this takes time and hence please use this as a first approximation.