LiPF6 is highly corrosive and readily decomposes in water to produce HF. Its organic solvents and decomposition and hydrolysis products cause severe pollution to the atmosphere, water, and soil, and harm ecosystems. Heavy metals such as copper accumulate in the environment, ultimately harming humans through the food chain. Phosphorus, once it enters lakes and other water bodies, easily causes eutrophication. Therefore, it is evident that failure to recycle discarded lithium iron phosphate batteries poses a significant threat to both the environment and human health.
With the rapid development of China's electric vehicle industry, the demand for lithium iron phosphate batteries has also increased rapidly. A large number of lithium iron phosphate power batteries are becoming obsolete and entering the recycling stage, leading to explosive growth in the lithium battery recycling market. So, what problems currently exist in the recycling of lithium iron phosphate batteries?
I. Immature recycling technology
Existing data indicates that the recycling and processing of waste lithium iron phosphate batteries can be divided into two types: one is to recover the metals, and the other is to regenerate the lithium iron phosphate cathode material.
(1) Wet recovery of lithium and iron
This type of process mainly focuses on lithium recovery. Since lithium iron phosphate does not contain precious metals, the recovery process for lithium cobalt oxide needs to be modified. First, the lithium iron phosphate battery is disassembled to obtain the positive electrode material, which is then crushed and sieved to obtain powder. Next, an alkaline solution is added to the powder to dissolve aluminum and aluminum oxides, and the mixture is filtered to obtain filter residue containing lithium, iron, etc. The filter residue is then leached with a mixed solution of sulfuric acid and hydrogen peroxide (reducing agent) to obtain a leachate. Alkali is added to precipitate ferric hydroxide, and the mixture is filtered to obtain a filtrate. The ferric hydroxide is then calcined to obtain ferric oxide. Finally, the pH value of the leachate is adjusted (5.0-8.0), the leachate is filtered to obtain a filtrate, and solid sodium carbonate is added to concentrate and crystallize the filtrate to obtain lithium carbonate.
(2) Regenerated Lithium Iron Phosphate
Recycling only one element results in relatively low economic benefits from the recovery of lithium iron phosphate batteries, which do not contain precious metals. Therefore, solid-phase regeneration of lithium iron phosphate batteries is the primary method for treating waste lithium iron phosphate batteries. This process offers high recycling efficiency and a high rate of comprehensive resource utilization.
First, the lithium iron phosphate battery is disassembled to obtain the cathode material, which is then crushed and sieved to obtain powder. Next, heat treatment is performed to remove residual graphite and binder. Then, an alkaline solution is added to the powder to dissolve aluminum and aluminum oxides. Filtering is performed to obtain filter residue containing lithium, iron, etc. The molar ratio of iron, lithium, and phosphorus in the filter residue is analyzed. Iron source, lithium source, and phosphorus source are added to adjust the molar ratio of iron, lithium, and phosphorus to 1:1:1. A carbon source is added, and the mixture is ball-milled and calcined in an inert atmosphere to obtain a new lithium iron phosphate cathode material.
II. Inadequate Recycling System
Although regulatory authorities and enterprises are vigorously promoting lithium iron phosphate batteries, recycling is still in its early stages due to the large-scale deployment in vehicles. The existing recycling system is incomplete, and a systematic and professional recycling system for automotive power batteries has not yet been established. The existing recycling system has certain problems and low recycling efficiency. These problems are mainly caused by the following factors:
1. Low recyclability
A large number of used batteries are scattered among the public, but there is nowhere for them to dispose of them. As a result, they are disposed of together with household waste, resulting in almost zero recycling of used batteries from individuals. The vast majority of recycled batteries are waste materials generated during the production process of manufacturing enterprises or old stock materials. The number of large power batteries recycled is even smaller.
2. Inadequate recycling system
A dedicated battery recycling system has not yet been established in China; collection is mainly done by small, inefficient workshops. my country is a major producer and consumer of lithium-ion batteries, but due to its large population, the per capita battery ownership is relatively low. For a long time, recycling companies have not collected individual lithium-ion batteries that lack recycling value.
3. High entry barriers
Enterprises wishing to engage in the recycling and disposal of waste batteries must apply for a hazardous waste operation license in accordance with the provisions of the "Environmental Protection Law of the People's Republic of China" and the "Administrative Measures for Hazardous Waste Operation Licenses". However, there are not many enterprises that can meet the qualifications for large-scale recycling. Instead, there are a large number of small-scale and low-tech companies, which makes it difficult to collect batteries in a centralized manner.
4. High recycling costs
A large amount of lithium iron phosphate materials are used in the cathode of power or energy storage batteries, and the demand is far greater than that of ordinary small batteries. Recycling them has high social value, but the recycling cost is high, and lithium iron phosphate batteries do not contain precious metals, so their economic value is low.
5. Weak awareness of recycling
For a long time, my country has had little publicity and education on the recycling of waste batteries, resulting in a lack of in-depth understanding among citizens of the pollution and harm caused by waste batteries and a failure to develop a conscious awareness of recycling.
