It is expected that in the next three to seven years, other new battery technologies will not be able to replace lithium-ion batteries
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【Kooban】:
　　 Testing, scoring, and verification are all terms favored by project developers and investors. After all, taking these measures can reduce investment risks and increase people’s trust in new technologies, no matter what industry they are in. Based on this, the global quality assurance and risk management consulting company DNVGL released the third-generation battery performance scorecard.

　　 In this year’s DNVGL evaluation, 22 companies provided battery products for testing the DNVGL battery scorecard. DNVGL stated that it will continue to work with technology partners to increase transparency. Even if no battery manufacturer is willing to reveal its name, this is still an ongoing process.

　　Industry analysts said that due to recent technology and market trends, lithium iron phosphate (LFP) batteries, including those used in stationary energy storage systems, are regaining popularity. The battery dominated the market from 2012 to 2015, but was replaced by nickel manganese cobalt (NMC) and nickel cobalt aluminum (NCA) ternary polymer lithium batteries after 2016. However, current Chinese battery manufacturers, such as CATL and BYD, have seen the potential and trend of the development of such batteries, and have promoted the development and production of lithium iron phosphate (LFP) battery technology.

　　 The third annual battery scorecard released by DNVGL tested the charge-discharge and temperature-dependent behavior of 22 batteries with different chemical properties, and identified important product trends.

　　The battery is getting bigger and bigger

　　 Another obvious trend is the increasing capacity of batteries in energy storage systems. The current capacity of lithium iron phosphate batteries is about 200Ah. The reason is that larger batteries can save raw material costs.

　　 Further innovations in electrode material selection, battery structure and system structure are expected to be realized in the next few years, and no major innovations in battery technology are expected. DNVGL has maintained its position as the number one choice in the field of energy storage. The company said that it does not expect other battery technologies to replace lithium batteries in the next three to seven years because they will benefit from economies of scale in applications in transportation, consumer electronics, and energy storage.

　　 According to DNVGL’s research, the current price of lithium batteries is about US$100/kWh. Its analysts predict that the price of battery storage systems will drop significantly in the next ten years.

　　Deploy more solar + energy storage projects

　　 Another trend observed by analysts is that more energy storage systems coexist with solar or wind energy facilities. Therefore, energy storage project developers and users require a battery life of 20-25 years for their battery storage systems to match the operating life of power generation facilities. Developers deploying grid-scale battery storage systems have responded to this demand, including comprehensive overhaul, enhancement, operation and maintenance services in their battery storage system deployment contracts.

　　DNVGL said that the way the battery is used will also change. In the early application of energy storage systems, commercial service projects were mainly user-side energy storage systems. Today, more and more battery storage systems need to shift solar power from day to night during peak demand periods. This puts forward different requirements for battery technology, including the stability of battery charging and discharging under different charging states and battery degradability.

　　DNVGL tested the charge and discharge stability of 22 products on the scorecard, and determined the number of charge and discharge times required to cause 1% capacity loss. In this year’s scorecard, the average number of charge and discharge times required to cause 1% of capacity loss is 381, and these batteries vary greatly: 135-448 times for lithium iron phosphate batteries, 180-849 times for NMC batteries, and NCA The battery is 143-330 times, and the best performing titanate battery is 1067 times.

　　Capacity statistics after charging and discharging

　　The research institute concluded through experiments that the average capacity of the battery will drop to 90% of the nameplate capacity after 1800 times of charging and discharging. The scorecard emphasizes the need to understand this degradation as a function of temperature. All charging and discharging are carried out at 10°C. After an average of 1000 times of charging and discharging, the battery capacity drops to about 85%. DNVGL’s test team has observed this temperature sensitivity in all battery products. The titanate battery performed best, maintaining 90% of its nameplate capacity after 8,609 charge and discharge cycles. Two NMC ternary lithium batteries followed closely, losing 10% of their capacity after 6410 and 4,500 recharges.

　　 In terms of state of charge (SOC), the scorecard found that the state of charge window is 50%-80%, and the NMC ternary lithium battery is more prone to degradation at this time. The lithium iron phosphate battery (LFP) is prone to degradation during the 30% ~ 40% SOC window period. DNVGL stated that it is very important to evaluate the main degradation carriers in battery projects, such as SOC, charging rate and temperature. The latter two are usually the main causes of battery degradation. Depending on the battery characteristics, the operating range of the SOC may be the second consideration, the scorecard researchers said.

　　The charging rate is a more important factor, and generally a lower charging rate is better for the battery. In the DNVGL test, lithium iron phosphate (LFP) and titanate batteries generally have a higher charging rate. Although the tester noticed that many NMC ternary lithium batteries also perform well, the temperature will increase at high charging rates.

　　 Scorecard researchers also pointed out developments in security. Standards such as the UL9540A protocol require improved testing and a step towards safety and transparency. But DNVGL said that the lack of new standard classification and non-conformance standards are confusing. Container storage solutions are constantly evolving, which means that the battery storage system can be fully accessed from the outside, avoiding the risk of operators and maintenance personnel entering the container. Dnv-gl scorecard researchers added that many battery suppliers are working to improve battery fire safety standards to prevent thermal runaway chain reactions.