On July 23rd, the website of the National Development and Reform Commission announced that in order to achieve carbon peak and carbon neutrality, and strive to build a clean, low-carbon, safe and efficient energy system, the National Development and Reform Commission and the National Energy Administration have issued guidance on accelerating the development of new energy storage. The opinion points out that by 2025, the transformation of new energy storage from commercialization to large-scale development will be achieved, with an installed capacity of over 30 million kilowatts (30GW); By 2030, achieve comprehensive market-oriented development of new energy storage.



The new energy storage refers to new energy storage technologies in addition to traditional energy storage technologies such as pumped storage, including electrochemical energy storage, compressed air, flywheel energy storage, thermal energy storage, etc. According to incomplete statistics from the CNESA Global Energy Storage Project Database, as of the end of 2020, the cumulative installed capacity of China's power storage projects that have been put into operation reached 33.4GW, of which pumped storage accounts for more than 90%, while the total installed capacity of electrochemical energy storage has not yet reached 2GW. According to the guidance, the installed capacity of new energy storage will increase from around 3GW to 30GW within 5 years, with an average annual increase of about 60% of installed capacity. This will be a staggering growth and also indicates a huge new energy storage market.



The guidance requires adhering to the diversification of energy storage technologies, promoting the continuous cost reduction and commercial scale application of relatively mature new energy storage technologies such as lithium-ion batteries, achieving the early stage of commercial development of long-term energy storage technologies such as compressed air and liquid flow batteries, accelerating the scale testing and demonstration of flywheel energy storage, sodium ion batteries and other technologies, and exploring the research and demonstration application of hydrogen storage, heat storage, and other innovative energy storage technologies based on demand. From this requirement, it can be seen that the current market maturity of new energy storage technologies is: lithium-ion batteries>compressed air/flow batteries>flywheel/sodium ions>hydrogen/heat storage. Lithium ion batteries have experienced rapid technological advancements and rapid expansion in production scale in the past decade, resulting in their cell costs rapidly decreasing from a few hundred dollars to below $200/kWh. However, due to the impact of raw material reserves and the sharp increase in demand for power batteries, the rapid cost reduction of lithium-ion batteries will be unsustainable. According to theoretical predictions, the installation cost of traditional lithium-ion batteries is expected to reach its limit of around $100/kWh in 10 years. Therefore, finding new technologies with more potential for price reduction is an urgent task.





Compared to developing new energy storage technologies, assembling energy storage modules using retired power batteries may be the least technically risky and easiest route to achieve large-scale industrialization. The retirement standard for power batteries is that when the capacity limit drops to around 80%, they no longer meet the requirements. If these retired batteries are directly recycled or destroyed, it will be a great waste. If it is continued to be used in other scenarios, it can achieve the full utilization of resources, so cascade utilization has emerged. According to statistics, the number of retired power batteries in China reached 20GWh in 2020, and is expected to exceed 90GWh by 2025. Comparing 90GWh with the proposed new energy storage capacity of 30GW by 2025, theoretically, relying solely on cascade utilization can meet the requirements. Of course, this is the most ideal situation. In fact, the biggest risk of cascading utilization is security, which is also the most urgent problem to be solved in the current cascading utilization industry chain. Next, we will outline the basic process of cascading the utilization of the industrial chain.





Firstly, the recycling of retired power batteries. Electric vehicle manufacturers and power battery manufacturers have a significant natural advantage in this regard, as they can incentivize consumers to return retired batteries to their original factories through trade ins or contracts signed when selling new batteries.



After the battery is recycled, a quick empirical inspection should be conducted first, such as visual or precise measurement of whether there is significant deformation in the external dimensions of the battery, and whether the packaging is damaged. Then perform instrument testing on all the selected batteries, record the operation of the batteries through several cycles of deep charging and discharging, record various parameters, and analyze whether there are any abnormalities in the batteries. This step usually requires a lot of manpower and time, but as the BMS battery management system for new batteries becomes increasingly sophisticated, many recycled battery systems may come with previous operating records and real-time parameters, saving a lot of measurement work. This feature is a good reminder for current battery and automotive manufacturers to improve their products. Finally, it is necessary to conduct spot checks on the safety of the batteries, selecting qualified batteries in a certain proportion for destructive tests such as compression, overcharging, puncture, and temperature cycling, in order to calculate the safety of the same batch of batteries.



After the battery screening is completed, the subsequent assembly process is similar to the assembly process of a new battery. Due to the generally lower safety of retired batteries compared to new batteries, it may be necessary to improve safety standards in battery temperature detection, insulation materials, and other aspects to ensure the safety of battery packs. The battery management system may need to consider safety redundancy parameters more carefully, and the requirements will be higher compared to systems with new battery packs.





Overall, the cost of cascading the utilization of retired batteries mainly comes from battery testing and reassembly. Although its total cost will be significantly reduced compared to using new batteries, the cost paid is a relative decrease in safety. Since the explosion at the Dahongmen Cascade Energy Storage Power Station of Beijing Jimei Home Furnishings on April 16 this year, which resulted in the sacrifice of two firefighters, the National Energy Administration has temporarily suspended the construction of new units for the large-scale cascade energy storage power station and required strict safety standards to be introduced before resuming construction. Therefore, cascading utilization only solves the cost issue of energy storage and does not address safety concerns. To completely solve the safety hazards of flammability and explosion, it is necessary to choose completely different new energy storage technologies, such as flow batteries or flywheel energy storage. From another perspective, these different new energy storage technologies have their own specific energy storage duration and application scenarios, so they are not directly competitive with each other, but rather meet a wider market demand through complementarity.





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Reference:

1. Some thoughts on the cascading utilization of power batteries. Energy Storage Science and Technology, 2020, V9, P598.

2. Key technologies and current situation analysis for the cascading utilization of retired power batteries. Power System Automation, 2020, V44, P172.



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Author Introduction:

Dr. Xie Wei, Bachelor and Master of Materials Science from Tsinghua University, and Ph.D. in Chemical Engineering from the University of Texas (Austin) in the United States. Mainly engaged in the development of energy storage batteries, has held important positions in multinational corporations and startups, led multiple research and development projects funded by the US Department of Energy, and won the 2013 US Annual 100 Best Research and Development Technology Award. Published 17 papers in top journals in materials science and energy storage, served as a reviewer for 5 international journals, and has applied for 17 international invention patents.



Introduction to ZH Energy Storage Company:

Shenzhen ZH Energy Storage Technology Co., Ltd. is committed to the research and development, promotion, and application of energy storage technology, aiming to help achieve China's goal of "carbon neutrality" through the application of electrochemical energy storage technology. In the early stages of development, the company focused on providing technical support and consulting services to the Chinese energy storage market by leveraging its accumulated industry experience and outstanding research and development capabilities in the field of energy storage. At the same time, the company focuses on conducting research and analysis on the Chinese energy storage market, and developing or introducing the most advanced and effective energy storage technologies for the Chinese market.

Company's technical research and development direction: water-based energy storage batteries, lithium-ion battery materials, fuel cells, ion exchange membranes, coatings and adhesives, membrane separation technology.

Domestic business: Technical cooperation and academic exchange between liquid flow batteries and high-energy density lithium-ion batteries, technical lectures on the company's technology research and development direction, research and development consulting, and guidance on paper writing.