Author: Zhu Yulong

From 2016 to the first half of 2022, the clean energy equipment testing organization ITP Renewables has released a total of 12 “lithium-ion battery tests” covering different energy storage battery test data from phase 1, phase 2, and phase 3. These data have provided us with intuitive results on the current battery performance, capacity retention rate, and charge and discharge efficiency.

I understand that, like pure electric vehicles, energy storage systems undergo EOL testing, and the likelihood of early failures is not high. However, many issues are skewed towards electronics. Currently, the overall results of battery SOH are good.

Figure 2 shows the batteries tested in the three stages, with no lead-acid batteries (proven to be unsuitable for energy storage applications). The focus is mainly on the ternary and LFP batteries – LFP’s performance is excellent due to its cycle life characteristics. FZSoNick’s sodium-ion battery products are also receiving attention.

Test Lifespan

Phase 1

Sony’s energy storage batteries ran smoothly among several others. From 2016 until the end of the entire test, the battery capacity showed a linear decline initially, but has recently stabilized. SOH remained at 81% after 3680 cycles and dropped only 2% in the last 1000 cycles, reaching 83% after 2500 cycles.

According to the calculated data, it is expected that the Sony battery will have an SOH of about 60% after 7390 cycles.

Phase 2

The batteries in the second phase include BYD, PylonTech and LG Chem RESU HV:

◎ LG Chem RESU HV is a 3-element product with 2040 cycles and an SOH of 75%.

◎ PylonTech’s US2000B product has been tested for 2830 cycles and has an SOH of 77%.

◎ BYD’s B-Box LVS has 1060 cycles and an SOC of 93%.

◎ Tesla Powerwall 2 has an SOC of 79% and has cycled 2520 times.

![▲Figure 4. Main batteries in phase 2(https://42how-com.oss-cn-beijing.aliyuncs.com/article/image_20221210134712.png)

If the battery capacity reaches 60% based on current estimates, the cycles required are:

◎ 5,640 cycles for BYD’s LVS.

◎ 1,270 cycles for GNB of the U.S. Exide Technologies Group.

◎ 3,360 cycles for LG Chem RESU HV.

◎ 4,995 cycles for PylonTech.

◎ 4,885 cycles for Tesla Powerwall 2.

These are estimated results, and of course, these data are not of great concern to homeowners – if one cycle is done every day, 1000 cycles will be completed in three years, and personal consumers really won’t mind what happens after 2000 cycles in 6 years. This area is currently mainly focused on large energy storage systems, which have made requirements at the infrastructure end.

Phase 3

The third phase has a shorter testing cycle, and similar to BYD, by updating the SOC window, available capacity is further increased. The currently effective and comparable data are as follows:

◎ Fimer React 2 battery module still has 86% capacity after 1740 cycles, as shown in the longer line in the figure below.

◎ FZSoNick has 880 cycles, with an SOH of 94%, using a Na-NiCl2 system.

These test results can objectively reflect the possibility of developing long-life battery cells, and can actually help us objectively evaluate the possibility of batteries with multiple recycling cycles, from battery cells to other peripheral components. The valuable aspect of this life test is that it injects temperature and SOC into the Cycles from 20% to 80%, as shown in Figure 6 below. Of course, this cycle is very gentle.

Price of Energy Storage Batteries

The price for energy storage seems to be relatively high after various expenses. The systems for home energy storage are still at around 500-600 dollars/kWh. Under the demand in the US and Europe at present, battery prices are indeed not a big concern. In 2022, the cost of energy storage products has reached a high point due to the increase in raw material costs, global component shortages, and increased transportation costs. As energy storage batteries begin to expand gradually, this price will continue to decrease. However, due to the large fluctuations in overseas electricity prices, demand for energy storage is increasing particularly fast in this area.

Conclusion: I think this testing institution has spent a lot of time showing everyone the actual performance of energy storage batteries. As for concerns about battery life, I now see data as not being a big problem, and actually we will not use that many Cycles under non-heavy load conditions. These data are still of great value for everyone to reference!

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This article is a translation by ChatGPT of a Chinese report from 42HOW. If you have any questions about it, please email bd@42how.com.