With the accelerating pace of industrialization of new energy vehicles in my country, the output of power batteries is also increasing year by year, and the field of power battery recycling and reuse is gradually becoming a new industry trend. When the capacity of a power battery decays to below 80% of its rated capacity, the power battery will no longer be suitable for electric vehicles. At this point, it is too early to scrap and recycle it directly. In addition to dismantling and extracting valuable metal materials, the secondary use of retired power batteries is also an important recycling method.
Regarding the secondary use of power batteries, Wang Jingzhong, vice chairman of the China Battery Industry Association, previously stated that retired batteries with sufficient remaining charge and stable quality assurance can be repurposed for energy storage, low-speed vehicles, and other fields through secondary use. Leading companies in the secondary use of power batteries are mostly battery recycling companies, such as Zhongtian Hongli, Ganzhou Haopeng, and Saidemei. Besides energy conservation and environmental protection, the secondary use of power batteries can effectively reduce manufacturing costs, extend their lifespan, and improve economic efficiency.
The scenarios for tiered utilization are wide-ranging.
In my country, most retired power batteries are currently lithium iron phosphate (LFP) batteries. From a performance perspective, LFP batteries offer greater stability in their reuse. Previously, Professor Li Jian of Central South University stated, "Currently, nearly 90% of low-speed electric vehicles in my country are equipped with lead-acid batteries, which have a price advantage. If costs can be effectively controlled, when the price of reused power batteries approaches that of lead-acid batteries, their advantages in weight, range, and charge/discharge time will become even more pronounced."
Compared to their applications in low-speed vehicles, retired power batteries may have a wider range of applications in energy storage. In March 2018, the "Notice on Organizing and Carrying Out Pilot Work on the Recycling and Utilization of Power Batteries for New Energy Vehicles," jointly issued by seven national ministries, explicitly stated its support for companies such as China Tower Corporation to carry out demonstration projects for the cascade utilization of power batteries in conjunction with pilot projects in various regions.
Application of secondary batteries in energy storage
With the gradual improvement of my country's energy storage database in recent years, the application of cascaded batteries in the energy storage field has become increasingly clear. Currently, my country has successively launched demonstration projects for cascaded utilization in areas such as large-scale renewable energy grid connection, ancillary services, power transmission and distribution, and user-side energy storage applications. These include kilowatt-level residential energy storage products, 10-100 kilowatt-level photovoltaic-energy storage microgrids, energy storage systems for electric vehicle charging stations, backup power supplies for data centers, and megawatt-level large-scale energy storage power stations. According to relevant institutions, the market demand for energy storage in my country will continue to grow in the future, and energy storage may become an important application scenario for the cascaded utilization of power batteries.
Experts say that communication base stations are a very suitable application for the reuse of power batteries. With the increasing density of 4G and 5G network base stations, the demand for reused power batteries will gradually increase. In 2018, China Tower stopped purchasing lead-acid batteries and switched to purchasing reused batteries. Gao Buwen, Vice President of China Tower, stated that the total battery capacity of China Tower's base stations nationwide exceeds 40 GWh. It is understood that in 2019, China Tower expected to use approximately 5 GWh of reused batteries, replacing about 150,000 tons of lead-acid batteries and disposing of over 50,000 tons of retired power batteries.
In 2018, my country saw a relatively large number of projects utilizing retired power batteries for energy storage in industrial and commercial settings, with companies such as Zhongheng Electric, Great Wall Power, and Changneng New Energy all making moves in this field. In September 2018, a 1MW/7MWh cascaded utilization industrial and commercial energy storage system project, jointly undertaken by Zhongheng Electric's subsidiary Xuda New Energy and Zhongheng Pury, was put into operation in Rudong, Nantong, Jiangsu Province, achieving commercial operation. In June 2018, Great Wall Power's factory completed the assembly and testing of a 50kW/150kWh energy storage container and successfully shipped it. The 150kWh lithium batteries in this project all used retired electric vehicle batteries, and the battery packs were directly reused without dismantling. In May 2018, Changneng New Energy's lithium battery cascaded energy storage power station was delivered and put into use in the Wujin National High-tech Industrial Development Zone Innovation Industrial Park.
In the area of microgrid energy storage, in August 2018, the Guangzhou Power Supply Bureau's high-reliability smart low-carbon microgrid project was put into operation in Nansha. It is understood that the Nansha microgrid project can achieve seamless switching from unplanned grid connection to islanded operation within 50 milliseconds, intelligent switching between four grid-connected/islanded operation modes, cascade utilization of retired power batteries, and the ability to operate on an islanded grid for one week. This project utilizes retired electric vehicle power batteries, realizing the cascade utilization of retired batteries in microgrid energy storage and improving resource utilization efficiency.
In the field of integrated photovoltaic, energy storage, and charging systems, the new charging spaces put into use at the Liuhe Service Area of the Changshen Expressway in Nanjing, Jiangsu Province in March 2018 all utilize retired power batteries. As part of an integrated photovoltaic, energy storage, and charging power station, this project has realized the application of photovoltaics, energy storage, and charging piles in a practical scenario.
A series of applications demonstrate that the use of cascaded batteries in the energy storage field has a promising future. Peng Qingfeng, Vice President of Hozon New Energy Automobile and Dean of Hozon Automobile Engineering Research Institute, previously stated that "the cascaded utilization of power batteries will become a very promising business model in the 'aftermarket' of new energy vehicles."
Problems of tiered utilization
Currently, my country is at a crucial turning point in the large-scale retirement of power batteries. The country is still in the exploratory and developmental stage regarding the secondary use of power batteries, and there is still much controversy surrounding its market prospects. Huang Shilin, Vice Chairman and Chief Strategy Officer of CATL, has publicly stated that "the secondary use of power batteries for energy storage is a false proposition."
Currently, some problems still hinder the development of the secondary utilization of power batteries in my country.
First, the cost of tiered utilization is relatively high. According to experts, given my country's current technology and processes, the cost of tiered utilization of power batteries is not particularly advantageous. Furthermore, as power batteries degrade, their lifespan is significantly reduced. The hidden costs associated with recycling, transportation, evaluation, and testing retired power batteries are also high. Some industry insiders believe that these issues will create confusion when choosing between new batteries and those intended for tiered utilization.
II. Lack of Battery Inconsistency. Since my country first launched a demonstration research project on the cascade utilization of power batteries in 2014, the issue of battery consistency has been a significant challenge in the operation of such projects. It is understood that the inconsistencies exhibited by power batteries in terms of capacity, internal resistance, and voltage are closely related to the battery's own charging and discharging reaction mechanism. Previously, Lai Xiaokang, an expert from the China Electric Power Research Institute, stated that "even with carefully selected retired batteries, it is still impossible to completely avoid the recurrence of inconsistent battery performance during system operation when constructing a cascade utilization energy storage system."
Third, the technological approaches differ. Some experts have stated, "Some people think that since energy storage batteries are just sitting there, their technological requirements aren't that high. Actually, from different perspectives, the technological requirements for energy storage batteries may be higher in certain aspects." Some industry insiders also believe that the future battery needs of electric vehicles and energy storage will differ. Electric vehicles tend to use power batteries with high energy density, while energy storage prioritizes batteries with high cycle life. Therefore, the technological approaches for power batteries and energy storage batteries will diverge. Furthermore, there are still some uncertainties regarding the future use of ternary lithium-ion batteries in energy storage, such as potential safety hazards and the ability to guarantee their stability.
Fourth, inconsistent value assessment. Currently, the market price range for retired power batteries is quite wide, and there is no unified standard in the industry for assessing the remaining value of retired batteries. Experts from the Southern Power Grid Electric Power Research Institute believe that data such as the actual remaining capacity, health status, estimated remaining cycle life, and total discharge capacity over the entire life cycle of a battery (or battery pack) have a direct impact on its market value. However, currently, there is no consensus among automakers, users, recycling organizations, and energy storage power stations on how to assess the value of retired batteries.
Multiple strategies, forging ahead
Despite numerous doubts and challenges surrounding the secondary use of power batteries, the industry has never stopped moving forward in this direction, constantly making breakthroughs and growing. Many companies have gradually realized the importance of secondary use of power batteries for my country's new energy vehicle industry and have begun to invest in this area, forging ahead amidst controversy.
According to incomplete statistics, a number of power battery and upstream and downstream companies, including BYD, CATL, CALB, Sunwoda, GEM, ZTE Power, Narada Power, Shanshan, Zhongtian Energy Storage, Camel Group, Mengshi Technology, Sandon New Energy, Xiongtou Power, Guoxuan High-Tech, Kelun Electronics, and Puneng Company, have all made moves in the field of power battery recycling. For example, Camel Group announced in 2018 that it planned to invest 5 billion yuan to build a power battery cascade utilization and recycling industrial park; Dongfeng Motor is deploying commercial energy storage through recycled battery energy storage equipment, utilizing peak-valley electricity price differences or renewable energy charging to power electric vehicles and society; WM Motor is developing a microgrid photovoltaic energy storage charging and discharging integrated system using cascaded batteries...
Currently, the promotion of the cascade utilization of power batteries in my country has achieved initial results. Starting with pilot projects, data and experience are gradually being accumulated, and research is being conducted on the different performances of various power batteries during the cascade utilization process, laying a solid foundation for the large-scale cascade utilization of power batteries in my country in the future. In the future, with the continuous improvement of my country's power battery recycling system and the collaborative efforts of all parties, the current problems facing the cascade utilization of power batteries will be gradually resolved, and the value of power batteries throughout their entire life cycle will be more fully realized. With strong support from national policies, whether the cascade utilization of power batteries will become the next big trend remains to be seen.
