The chocolate swapping electric blocks is an idea from CATL to standardise the swappable battery. Hence important that we look at the format and options that come along from different manufacturers.
- 20# Block:Designed for smaller A-segment vehicles.
- LFP battery: 42 kWh, up to 400 km range.
- NMC battery: 52 kWh, up to 500 km range.
- 25# Block:Designed for A and B-segment vehicles.
- LFP battery: 56 kWh, up to 500 km range.
- NMC battery: 70 kWh, up to 600 km range.
The blocks as launched in 2024 are NMC and LFP with a maximum gravimetric energy density of 160 Wh/kg and a volume energy density of 325 Wh/litre.
The design is such that customers can install one to three of the battery packs.
Nio Firefly Battery
The 2025 Nio Firefly battery uses LFP cells from Sunwoda and is design to the CATL Choco-SEB swappable standard.
- 42.1kWh pack with 41.2kWh usable
Trouble is the image shows a very different design to those released by CATL for their chocolate block battery. Maybe something missing in what we are seeing / understanding of the design.
References
- CATL EVOGO / Choco-SEB – CATL’s own product page for the Choco-SEB block and EVOGO swap system, confirming the 160 Wh/kg and 325 Wh/L figures cited above. Note: this is CATL’s marketing/product description, not a published interoperability standard document – no formal spec has been located, so treat exact mechanical/electrical interface details as unconfirmed.