Yesterday we brought news of Geely’s latest generation Aegis short blade battery, today we bring you more details about the battery. Firstly it seems the official name in English is just ‘New Short Blade EV Battery Technology’ according to Geely who don’t mention the Aegis name.
Although the most important specification is still the 192 Wh/kg energy density, there are now many more elements known about the battery, its capabilities and its safety. A lithium iron phosphate battery, Geely claims it has best-in-class battery life, charging speed – and ultimate safety.
Geely’s short blade battery is 580 mm long which is about 40% shorter than a traditional long blade battery which results in less internal resistance and heat generation while increasing volume utilization by 50%.
The short blade battery in testing has achieved 3,500 charging cycles. This Geely claims is equivalent to charging and driving for 1 million kilometers. More importantly this is meant to have minimal impact on battery attenuation helping extend the useful life of the battery and improving residual values for second hand EVs. Geely without providing any details of how the figure was arrived at states that it reduces carbon emissions by 80,000 tons a year. To put the 1 million kilometers in perspective it is enough for a car to average 20,000 km a year for 50 years.
Another key claim of the new short blade battery is that it has super fast charging and stable low-temperature performance. Geely’s battery has charged 10-80% in 17 minutes 4 seconds with an average charging rate of 2.45C this is around 1.5 times faster than a long blade battery which takes around 26 minutes and has an average of 1.61C. EVs generally suffer range degradation with cold temperatures and with long blade batteries at a temperature of -30°C capacity retention rates average at 78.96% while for Geely’s new battery it retains 90.54% of its capacity.
This has been achievable by the use of long, thin carbon nanotubes in the battery to aid ion transmission together with additives to improve film permeability. These changes make it easier for the lithium ions to travel between the electrodes so improving fast charging performance.
The battery has passed six extreme tests which include: seawater corrosion immersion, extreme cold environment, high-frequency pack bottom scraping, 26-ton overweight rolling, single-pack side collision, and fire roasting. These were carried out by the China Automotive Center and Geely’s battery passed them all. The tests are to a higher standard than required by the national standard and in the case of the scraping test requires it to be carried out 3 times, the rolling test withstanding a 26 ton weight, cold weather test withstanding -35°C at the equivalent of 5000m elevation for 8 hours, and for the roasting test a fire of 1000°C for 130 seconds.
Geely’s own tests involved a simultaneous puncturing of the battery by eight nails and after an hour there was no effect. Similarly, Geely fired a standard issue (5.8 mm) Chinese army rifle round at the battery without thermal ignition.
Such results are possible because the short blade battery uses “a high-strength, high-thermal stability, high-heat-resistant diaphragm, with a highly stable separator paired with safe electrodes resulting in higher energy density and safety.” There is also self-developed self-fusing technology on the surface of the electrode which blocks a short circuit if there is an accident. An aluminium foil layer fuses into the battery diaphragm creating an insulating layer if the battery cell experiences extreme shock and is punctured. Geely says the battery has a “patented grid frame design, energy-absorbing cavity, three-layer sandwich bottom guard plate, CTB (cell to body) integration, thermal runaway control system, and multiple other safety features.”
The new short blade battery will debut in the Geely Galaxy E5 SUV which will launch in early August. They will be used in both the 49.52 and 60.22 kWh packs delivering 440 and 530 kilometers CLTC range respectively. Also featured on the car is the Galaxy 11-in-1 intelligent electric drive system, and the E5 will have power consumption as low as 11.9 kWh/100 km.
Sources: Geely, Fast Technology
