1. Introduction
In recent years, the world has been experiencing a green energy revolution led by vehicle electrification and new energy storage technologies. In China, the “dual-carbon” strategy has been proposed to promote the optimization and adjustment of the traditional fossil energy and new energy production and consumption structures, aiming for a low-carbon energy transformation. Lithium-ion batteries, as the core components of new energy vehicles and energy storage devices, play a crucial role in this process. Among them, lithium iron phosphate (LiFePO4) batteries have gained increasing popularity due to their excellent cycling performance, high safety, and low production cost.
However, with the rapid growth of the LiFePO4 battery market, the issue of battery recycling has become a significant concern. As the first batch of LiFePO4 batteries approaches the end of their service life, improper disposal of these battery can lead to environmental pollution and resource waste. Therefore, the recycling and reuse of LiFePO4 battery have become essential for the sustainable development of the new energy industry.
This article focuses on the recycling of LiFePO4 battery, discussing their retirement and regeneration paths, summarizing the research progress of cathode waste regeneration, analyzing the key factors for industrialization, and exploring the development trends and challenges of lithium-ion battery recycling technologies. The aim is to provide a comprehensive understanding of LiFePO4 battery recycling and offer suggestions for its future development.
2. Retirement and Regeneration Paths of LiFePO4 Batteries
2.1 Retirement Paths
The retirement paths of LiFePO4 batteries mainly include echelon utilization and regeneration utilization.
- Echelon Utilization: After reaching the designed lifespan, LiFePO4 batteries can be reused in a suitable working environment through repair, modification, or remanufacturing. This usually involves downgrading the application while maintaining a certain level of battery capacity. For example, lithium-ion battery with a capacity attenuation of 20% – 40% can be used in communication base stations, solar streetlights, uninterruptible power supplies, and other small energy storage devices. The China Tower Corporation has achieved remarkable results in the echelon utilization of LiFePO4 batteries.
- Regeneration Utilization: For lithium-ion battery that have experienced one or two retirements and have a capacity attenuation exceeding 40%, regeneration utilization is required. This process involves extracting reusable materials from the retired battery through specific treatment and recycling processes to achieve resource recycling.
2.2 Regeneration Paths
The regeneration process of LiFePO4 battery consists of pretreatment and resource regeneration.
- Pretreatment: This is the first step in the regeneration of retired LiFePO4 batteries. It includes deep discharge, crushing and dismantling, and screening and classification. The purpose is to safely handle Lithium-ion battery with potential residual power and hazardous substances, and to separate the key components for efficient subsequent material regeneration.
- Resource Regeneration: This step focuses on the recycling of various components of Lithium-ion battery, such as the diaphragm, current collector, negative and positive active materials, and electrolyte. The positive active material, LiFePO4, is of particular interest due to its high value as a secondary lithium resource.
3. Research Progress in the Regeneration of LiFePO4 Cathode Wastes
3.1 Pretreatment
- Thermal Treatment: By exploiting the thermodynamic properties of PVDF, thermal treatment can completely decompose PVDF at high temperatures, reducing the impact of impurities. However, it requires a protective atmosphere to prevent the oxidation of LiFePO4 and potential reactions with other components.
- Mechanical Treatment: This method uses mechanical equipment to physically break down Lithium-ion battery components. While it can separate different parts, it may cause significant loss of the positive active material and ineffective removal of impurities.
- Chemical Treatment: Based on the chemical properties of the components, chemical treatment methods such as organic reagent dissolution and alkali dissolution can be used to separate the positive active material from the current collector. These methods can effectively address the issue of aluminum impurity removal.
3.2 Resource Regeneration
- Direct Regeneration: This process repairs the composition and structure of LiFePO4 on the basis of maintaining its original structure intact. It includes methods such as solid-phase repair, liquid-phase repair, and electrochemical repair. Direct regeneration has the potential for high application but is still in the initial research stage.
- Indirect Regeneration: This method first extracts valuable metal elements from the LiFePO4 cathode waste and then synthesizes new precursor or LiFePO4 products. It is suitable for situations with complex raw materials or high-value resource reserves.
3.3 Process Comparison
| Comparison Items | Direct Regeneration | Indirect Regeneration |
|---|---|---|
| Process Length | Short | Long |
| Efficiency | High | Varies |
| Energy Consumption | Low | High (especially for full leaching path) |
| Carbon Emissions | Low | High (especially for full leaching path) |
| Benefit | High | Depends on various factors |
| Raw Material Adaptability | High requirements | Good |
4. Industrialization Development of LiFePO4 Cathode Waste Regeneration
4.1 Important Factors for Industrialization
- Development Prerequisites: Safety, environmental protection, and economic viability are essential for the industrialization of LiFePO4 cathode waste regeneration. The recycling process must comply with safety regulations and environmental standards, and the economic benefits need to be considered comprehensively.
- Development Key: Technology transformation is crucial. The maturity of direct and indirect regeneration technologies needs to be improved to adapt to industrial applications.
- Development Guarantee: A stable resource recycling ecosystem is necessary, involving the stable supply of raw materials, optimization of Lithium-ion battery production process, construction of a waste recycling system, and promotion of the application of recycled materials.
4.2 Industrialization Example – LiFePO4 All-Component Short-Range Regeneration Utilization Technology
The IPE-BRUNP technology developed by the research team is an example of successful industrialization. It adopts an indirect regeneration path based on the selective separation of Li and FePO4, combined with various techniques for impurity control. This technology has been applied in a 10,000-ton LiFePO4 recycling production line in Yichang, Hubei, demonstrating good economic and environmental performance.
5. Development Trends and Application Challenges of LiFePO4 Battery Recycling Technologies
5.1 Development Trends
- Residual Energy Detection Technology: This technology is used to accurately assess the available energy of retired batteries. Future trends include the construction of more accurate multi-dimensional evaluation models, the application of intelligent technologies, and the standardization of detection methods.
- Intelligent Dismantling Pretreatment Technology: This technology aims to replace traditional dismantling methods with automated and intelligent ones, integrating various advanced technologies to improve dismantling precision, recycling efficiency, and safety.
- Direct Regeneration Technology of LiFePO4 Cathode Wastes: With the expansion of the LiFePO4 battery market, this technology shows promising application prospects due to its economic and environmental advantages.
5.2 Application Challenges
- Complex Raw Material Sources and Usage Conditions: The diversity of retired LiFePO4 battery sources leads to differences in design, specification, performance, and failure modes, making it difficult to develop unified recycling standards and processes.
- Removal of Multiple Metal Impurities: The presence of various metal impurities in LiFePO4 battery complicates the recycling process, as these impurities are similar in physical and chemical properties to the main recycled materials, affecting the purity and quality of the recycled products.
- Upgrading of Cathode Materials: The continuous upgrading of LiFePO4 cathode materials increases the difficulty of material separation and purification during recycling, requiring more complex and refined processes.
6. Suggestions for the Development of LiFePO4 Battery Recycling Technologies and Applications
6.1 Standardize Management and Smooth the Recycling Channel
- Accelerate the formulation of industry regulations for LiFePO4 battery recycling, clarify the responsibilities and technical requirements of each party, and establish a regulatory mechanism.
- Set up recycling stations at various locations and encourage cooperation among battery manufacturers, new energy vehicle enterprises, and battery recycling enterprises to build a comprehensive recycling network.
6.2 Accelerate the Breakthrough and Application Transformation of Key Technologies
- Encourage recycling enterprises to increase R & D investment, strengthen cooperation among universities, research institutes, and enterprises, and jointly tackle the challenges of industrialization.
- Establish a pilot base for LiFePO4 battery recycling technology and a service platform to provide technical support and promote the transformation and popularization of technologies.
- Cultivate and introduce professional talents in the field of battery recycling.
6.3 Strengthen Publicity and Promotion to Improve Market Acceptance
- Increase the publicity of the importance of battery recycling to raise public awareness and encourage voluntary participation.
- Enterprises in the recycling industry should cooperate to promote the secondary use of retired batteries in key fields such as energy storage.
- Conduct environmental protection education activities to enhance public environmental protection awareness.
In conclusion, the recycling of LiFePO4 battery is of great significance for the sustainable development of the new energy industry. Although there are still many challenges in the process of industrialization, through continuous research and development, technological innovation, and the joint efforts of all parties, it is expected to achieve more efficient and environmentally friendly recycling and reuse of LiFePO4 battery, promoting the green development of the related industries.