SK Energy to Invest $110M to Expand Li-Ion Production
27 October 2008
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| Energy and Power Densities of SK HEV/PHEV Cells (H65, H75, P155). Click to enlarge. Source: SK Energy |
South Korea-base SK Energy will invest 159 billion won (US$110 million) to expand its lithium-ion battery production, according to a filing with the Korea Exchange.
SK Energy was the first Korean company, and the third in the world, to independently develop a lithium-ion battery separator, which features proprietary technology for low shrinkage and heat resistance. The company began commercial Li-ion battery production in 2005, targeting mobile devices, and is developing high energy density power batteries for hybrid electric (HEV), plug-in hybrid electric (PHEV) and electric (EV) vehicles.
SK Energy uses LiMn2O4 (manganese spinel) as its cathode material. Manganese spinel enables a higher voltage cell with excellent safety characteristics; however, it has known cycle life problems because of manganese dissolution, which are exacerbated at higher temperatures.
To solve this, some cell developers have substituted amorphous carbon for crystalline carbon in the anode, resulting in reduced energy density due to the high initial irreversible capacity loss, according to SK Energy’s Jeon Keun Oh.
Instead, SK Energy is opting for crystalline carbon as the anode material to deliver a battery system with higher energy density. To address the problem of lifecycle decay at high temperature due to manganese dissolution, SK Energy uses a polymer gel ingredient, coated electrode materials and SEI enhancement additives.
As a result, said Oh at the 1st International Conference on Advanced Lithium Batteries for Automobile Applications, organized by Argonne National Laboratory, more than 90% of the power remains even after 200 days storage at 45°C. More than 70% of the capacity and power is maintained after 5,000 full cycles at 5C.
SK produced and tested prototype packs in HEV and PHEV vehicles for testing; these battery systems are now ready for production.
That P155 cell looks good, 140 Wh/kg is a full 40% better than the LiFePO4 of A123 etc.
5,000 cycles at 5C is also pretty impressive, that's equivalent to 12 minute full charges and discharges. Looks like we have a serious competitor to the titanate/phosphate race.
Posted by: clett | 27 October 2008 at 05:11 AM
5,000 cycles is great, but isn't using a 5C test temp kind of unrealistic? How fast is the drop off in cycles at 10C? The energy required to keep a battery pack at 5C for the 95% of the time the pack is not in use would cost you nearly as much money as the energy used to move you and your car. Isn't one of the first Tesla owners (ex-CEO Martin Eberhard) finding that 22% of his energy use is simply cooling his battery pack while his car is not in use? This could end up being even more expensive, or not. I don't have a clue as to what the Tesla's pack is cooled to.
That having been said, as a first step in the continued development of an alternative to the current favorite Li-Ion battery type, this is very interesting news.
Posted by: ziv | 28 October 2008 at 05:00 AM
Sheez!, 5C is not 5 degrees centigrade.. they are talking about charging/discharging (in amps) at 5 times the capacity of the battery (measured in amp/hours). Common Lipo talk, a dimensionless number.
Example, lets say we have a 300v pack, cells have a capacity of 6.0Ah.., since they are in series the pack also has a capacity of 6.0Ah.. the pack can be discharged at a rate of 6 * 5 or 30amps (for a 5C battery).
30Amps * 300Volts is 9000 watts or 12hp average (peak may be higher, but only temporarily or the cells overheat). Lets say you want at least 48hp average to drive a small car, then you would need 4 of those modules in parallel.. voltage is still 300v but now you have 24Ah of capacity. Total pack capacity is 300v * 24Ah = 7200 wh or more commonly 7.2kWh
Since 7200Wh will only give you a range of 36 miles if you dared to discharge the pack 100% (probably killing it for good) then most likely you will add more modules in parallel to get more capacity, and incidently increasing the hp available from the pack.
5C is just about perfect for cells intended for cars. Even lower performance would do just fine. The lower you keep the C discharge the cooler the batteries will run and the longer they will last in cycles.
Since the power density is 140wh/kg then we know that 7200wh pack will weigh 51kg, compared to 72kg for a LiFe pack.
Posted by: Herm | 30 October 2008 at 06:43 AM
5000 cycles at 5C to 70% degradation.. compared to 10,000 cycles for A123 cells?.. and what is the calendar life limit of the cells?.. lithium cells degrade just sitting there with time.
They should also mention how deeply they are discharging these cells to get 5000 cycles, I would assume 100% but you never know.. these battery articles without details are pretty useless.
Posted by: Herm | 30 October 2008 at 06:50 AM
This is good news. More players the better. Each manufacturer will find different improvement pathways and we should have much better units within 2 or 3 years.
Combo super-cap + best energy density batteries may be one way to capture maximum braking energy, ensure increased life cycles and get more e-miles with a smaller highly resistant pack.
Eventually, (2015?) we will see affordable 500 Wh/Kg, very quick charge units, for practical PHEVs and BEVs.
This could have been done 15+ years ago if enough R & D and production facilities had been fully financed with a mere $100B starting in 1974-75. Over 200 million PHEVs and BEVs could have been on the road already.
Posted by: HarveyD | 30 October 2008 at 06:58 AM
This is good news. More players the better. Each manufacturer will find different improvement pathways and we should have much better units within 2 or 3 years.
Combo super-cap + best energy density batteries may be one way to capture maximum braking energy, ensure increased life cycles and get more e-miles with a smaller highly resistant pack.
Eventually, (2015?) we will see affordable 500 Wh/Kg, very quick charge units, for practical PHEVs and BEVs.
This could have been done 15+ years ago if enough R & D and production facilities had been fully financed with a mere $100B starting in 1974-75. Over 200 million PHEVs and BEVs could have been on the road already.
Posted by: HarveyD | 30 October 2008 at 06:58 AM