Toshiba announced the launch of the new 20Ah-HP SCiB lithium-ion battery cells that appear to be a perfect compromise between the previous SCiB high-energy and SCiB high-power versions.
Let's recall that SCiB is a marketing name for Toshiba's version of the lithium titanium oxide (LTO) battery anode chemistry. It's a low voltage lithium-ion cell (2.3 V nominal), with relatively low energy density (between lead-acid and lithium-ion LFP), but with extreme longevity, charge/discharge capabilities, and wide operating temperatures.
As we can see in the chart below, the 20Ah-HP SCiB combination type provides almost as high energy density (84Wh/kg and 176Wh/L) as the previous 20 Ah/23 Ah SCiB high-energy type (respectively: 89 Wh/kg and 96 Wh/kg).
The charge/discharge power might be as high or even higher than in the case of high-power 2.9 Ah/10 Ah SCiB high-power versions. See the specs comparison at the bottom of this post.
Benefits of reduced internal resistance
The key technological improvement behind the 20Ah-HP is the reduction of resistance in the cell by approximately 40%.
It reduces heat generated when charging/discharging. The charging power has been increased by 70%, while discharging by 60%.
An additional effect is that the new cell is expected to be even more durable than the already durable previous SCiB types. The new cell can run 5C charge/5C discharge cycles from 10-90% state-of-charge (SOC) at 25°C 8,000 times and maintain almost 100% initial capacity. The previous type would be at 90% of its initial capacity.
The energy density of 84 Wh/kg does not appear high enough for electric cars, especially since the less expensive LFP battery chemistry offers much more (as far as we know, LTO is considered as one of the most expensive lithium-ion types).
However, SCiB is one of the go-to solutions for EVs with short range and ultra-fast charging features - in 10 minutes or so - multiple times per day. Buses are a perfect example of such an application - they can cover one route, recharge at the end in 10 minutes, and drive again - basically 24/7.
The Japanese lists also other potential applications:
"The cell is ideal for heavy-load applications where high power input and output are essential, and for situations where battery cells must suppress heat and operate continuously, such as rapid charging of commercial vehicles, regenerative power systems for rolling stock, and industrial equipment. The cell is the same size as Toshiba’s current 20Ah product, allowing current customers to easily upgrade to the improved input and output power with the same module pack. The cell is now available to order worldwide."
Toshiba 20Ah-HP SCiB features:
- Excellent heat suppression
Compared to Toshiba’s current 20Ah cell, the new 20Ah-HP cell delivers 1.7x higher input and 1.6x higher output, realized by an approximately 40% reduction of resistance in the cell. This improvement efficiently suppresses heat generation when a large current is applied, allowing design of a simpler cooling system. For example, depending on the customer's system, water cooling can be simplified to forced air cooling, and forced air cooling simplified to natural cooling. The lowered resistance also reduces overvoltage, allowing the cell to function in a wider range of state-of-charge (SOC).
- Long life
The new 20Ah-HP cell achieves a longer life than the current 20Ah cell by suppressing heat during continuous charging and discharging, due to its lower internal resistance. Under the test conditions shown in figure 1, the cell maintained almost 100% capacity after 8,000 charge/discharge cycles, while the capacity of the current 20Ah cell decreased by approximately 10%.
The new 20Ah-HP cell delivers improved input and output power but maintains the same size as the current 20Ah cell, allowing current customers to easily upgrade to the improved performance with the same module pack.
Toshiba 20Ah-HP SCiB specs:
- Product name: 20Ah-HP Cell
- Rated capacity: 20 Ah
- Nominal voltage: 2.3 V
- Input power: 1900 W* SOC 50%, 10sec, 25℃）
- Output power 1900 W* SOC 50%, 10sec, 25℃）
- Energy density (volume): 176 Wh/L
- Energy density (mass): 84 Wh/kg
- Dimensions: W116 × D22 × H106 mm
- Weight: Approx. 545 g