The BYD Blade pack design is the first cell to pack design that encompasses everything this means. Not having a module and the overhead of a module is difficult to achieve. LFP cells make this design easier in some ways and this gives a new lease of life for LFP chemistry. The Tesla with CATL’s LFP cells achieve 126Wh/kg at pack level compared to this Blade pack that achieves 150Wh/kg. A significant improvement, but this is quite a way behind the 82kWh Tesla Model 3 that uses an NCA chemistry and achieves 171Wh/kg at pack level.
The key to this Blade design are the very long cells that stretch across the width of the automotive pack.
The image shows the top panel removed and the faint lines show the ~100 to 120 cells running across the pack.
“The Blade Battery – Unsheathed to Safeguard the World”, Wang Chuanfu, BYD Chairman and President, said that the Blade Battery reflects BYD’s determination to resolve issues in battery safety while also redefining safety standards for the entire industry.
BYD’S NEW BLADE BATTERY SET TO REDEFINE EV SAFETY STANDARDS
Cell
BYD are able to make cells to a range of dimensions. The following set of specifications gives an example set of numbers that are consistent for this particular cell:
- Chemistry = LiFePO4 (LFP)
- Capacity = 202 Ah
- Nominal Voltage = 3.2 V
- Maximum Charging Voltage = 3.65 V
- Energy Content = 646.4 Wh
- Dimensions = 960mm (L), 90mm (W), 13.5mm (H)
- Volume = 1.17litres
- Volumetric Energy Density = 552 Wh/L
- Weight 3.9 kg [3]
- Gravimetric Energy Density = 166 Wh/kg
- Cycle Life 3,000+ cycles
- Chemistry = LiFePO4 (LFP)
- Capacity = 138 Ah
- Nominal Voltage = 3.2 V
- Maximum Charging Voltage = 3.65 V
- Energy Content = 441.6 Wh
- Dimensions = 960mm (L), 90mm (W), 12mm (H)
- Volume = 1.04 litres
- Volumetric Energy Density = 424 Wh/L
- Weight 2.63 kg [4]
- Gravimetric Energy Density = 168 Wh/kg
- Cell casing = aluminium
- Safety
- pressure relief valve
- short circuit protection in end plate
- Anode: 27 layers, 946 x 85mm
- Cathode: 26 layers, 944 x 83mm
- Cycle Life 3,000+ cycles
Pack Construction
In some of the Blade pack designs the control system is on the same plane and at the front of the cells. In other designs (left) the control system has been moved above the front of the pack.
Most vehicles have some form of tunnel section as it works structurally with the front longitudinals and bulkhead. Hence it makes sense to lift the control system into this volume.
In the pack shown here the electrical connections run down both sides of the pack. The cells arranged alternately +ve and then -ve to connect them in series. The overall +ve and -ve connections to the cells will then be made at the front left hand corner and rear right hand corner. Hence the busbar (above image) seen going from the control system to the rear right hand corner.
This busbar would be electrically isolated and positioned above the cooling plate.
Cooling
The cooling plate is a single large plate that is fixed to the top surface of the cells. The coolant connections are both at the front of the plate. This approach has a number of advantages:
- minimises joints and risk of leaks
- coolant connections outside of the pack
- coolant plate acts as another barrier between the cells and passengers
However, this does also have some significant challenges:
- manufacturing a flat plate
- thicker layer of thermal interface material to accommodate non-flatness
- equal coolant flow to all areas
Safety
BYD reports no fire or explosion from the following tests:
- crushed
- bent
- heated in a furnace to 300°C
- overcharged by 260%.
BYD Blade Nail Penetration Test
Overall, we know that Lithium Iron Phosphate chemistry is far less reactive in this test compared to NMC or NCA. However, there is a lot of variability based on the cell conditions and the test conditions. This is even shown by BYD in their own promotional material.
Metrics
- Pack Gravimetric Density ~ 150Wh/kg [3]
Applications
- BYD Han
- Tesla
- Toyota
References
- BYD’S New Blade Battery Set to Redefine EV Safety Standards, BYD News
- What Electric Vehicle Makers Don’t Get About BYD’s Game-Changing Battery, The Electric
- Tesla rumoured to have ordered battery cells from BYD, ElectricDrive.com
- BYD Blade Teardown, Electrios
CATL Qilin CTP Design
The CATL Qilin CTP 3.0 is their second generation cell to pack design. Qilin is named after a legendary creature from China.
The latest CATL post suggests that this integrated system can increase the energy density to 255Wh/kg for ternary battery systems (NMC, NMCX etc), and 160Wh/kg for LFP battery systems. Essentially removing the overheads of a module.
BYD blade battery pack has poor cooling, as cooling system is on the top of the cell. It has led to very high temperature and understand it has low life. Is it true?
Hi Shyam,
cooling plate on the top is not a bad position. Just depends on the mechanics of the thermal connections. I’ve not seen any evidence to suggest the lifetime of the BYD Blade pack is worse than any other pack as yet.
Would be good if someone has some data on the packs that they could share.
Best regards, Nigel
Isn’t each blade basically a module? They just replaced a module with many cells with a module with one cell.
They have been through a few iterations and started as effectively pouch cells in parallel and series inside an aluminium case with the CSC – just an odd shape module. I believe they are now an actual cell, but I must admit that I haven’t seen a breakdown. Anybody out there who can point us at a cell teardown?
#It is just one single long cell
# There is a cold plate passive cooling on the top and active cooling plate on the bottom
# the busbar has been moved to the side of the pack to give the whole plack a flat surface