1. Introduction

Accompanied by the recent global development and innovation in sustainable energy technologies, and the increasing demand, especially with the rapid growth of electric vehicles and large-scale clean energy storage systems, the demand for high-performance batteries has surged [1,2]. The core of battery performance lies in its active materials and electrochemical properties. These properties determine the charging speed, endurance stability, and battery lifespan [3]. Therefore, understanding and optimizing the electrical performance of these materials is key to improving battery technology. Similarly, further research and progress are needed in the degradation methods for high-demand batteries, including discovering new materials and improving old materials [4,5]. This discussion on these advancements can potentially drive battery technology forward.

Battery pollution is a significant environmental concern. While electric vehicles are seen as a perfect clean energy product, this study overlooks how batteries can pollute our ecological environment and cause irreversible damage [6,7]. This study needs to consider the disposal of end-of-life vehicles, proper handling of batteries, and environmentally friendly separation methods during recycling. There are different methods for handling batteries in this process [8]. Recycling discarded batteries is a complex but crucial process. This study also needs to minimize environmental impact and recycle valuable materials for reuse. This study mainly discusses three methods that can be used for recycling discarded batteries, including mechanical processing, chemical recovery, and direct reuse [9,10].

2. Methods of Battery Recycling

2.1. Mechanical Processing

Mechanical processing is a basic way to recycle waste batteries, which involves physically breaking the batteries down into small pieces and recovering valuable metals like nickel and copper through physical techniques such as magnetic separation, sieving, and gravity separation. advantages of this method are its simplicity and low cost, but the downside is significant; it may not fully recover all types of battery materials, especially rare metals and electrolytes, making its effectiveness less satisfactory over time [1].

2.1.1. Steps of Mechanical Processing

The specific process of this method includes several major steps [3]:

Crushing: Waste batteries are sent to a crusher for physical crushing, breaking the batteries into small pieces or fragments, typically ranging in size from a few millimeters to a few centimeters. These fragments include battery casings, electrode sheets, electrolyte, and other mixtures.

Magnetic Separation: The crushed battery fragments undergo magnetic separation. Magnets are used to separate ferromagnetic metals (such as iron and nickel) from other non-magnetic materials. These magnetic metals are collected for further processing and recycling.

Screening: The fragments that have undergone magnetic separation are screened to separate materials of different particle sizes using screens with different pore sizes. This process can further separate larger metal pieces or smaller metal powders.

Gravity Separation: The screened materials may undergo gravity separation, utilizing the density differences of materials to separate heavy metals from light metals for more efficient resource recovery.

The entire mechanical processing process is relatively simple to operate and low in cost, making it an economical and practical recycling method. However, it has limitations in fully recovering all types of battery materials, especially rare metals and electrolytes.

2.1.2. Disadvantages of Mechanical Processing

Although mechanical processing methods are simple to operate and low in cost, they also have significant drawbacks. Since this method mainly relies on physical separation techniques, it cannot fully recover all types of battery materials, especially some rare metals and electrolytes. Therefore, although this method is effective in recovering common metals such as nickel and copper, it is less effective in recovering some high-value, low-content metals. Additionally, the fragments produced during mechanical processing may be mixed with harmful substances, which, if improperly handled, can cause environmental pollution. With the development of technology and increasing environmental requirements, solely relying on mechanical processing can no longer meet the needs of modern battery recycling. Therefore, it is usually necessary to combine mechanical processing with other chemical or thermal treatment methods to improve recovery efficiency and material purity. This comprehensive treatment method allows various valuable components in waste batteries to be more comprehensively recovered, reducing resource waste and environmental pollution.

2.2. Chemical Recovery

Chemical recovery is an important means of processing waste batteries. By using chemical solvents such as acids or bases, the metals in the batteries are converted into soluble salts, which are then extracted using chemical precipitation or electrochemical methods [3].

2.2.1. Steps of Chemical Recovery

The specific process of this method includes several major steps:

First is dissolution, where waste batteries are crushed into small pieces and placed in a solution containing acids or bases. Common acids include sulfuric acid, hydrochloric acid, and nitric acid, while common bases include sodium hydroxide and potassium hydroxide. The metals in the batteries react with these chemical solvents to form soluble metal salts. For example, lithium in lithium batteries can react with sulfuric acid to form a lithium sulfate solution. Next is filtration, where non-metal parts of the batteries, such as plastics and other impurities, do not dissolve in the solution during the dissolution process. These insoluble need to be separated from the solution by filtration. The filtered solution mainly contains metal salts and a small number of soluble impurities.

Next is precipitation, whereby adding appropriate chemical reagents to the solution, specific metals can be precipitated out in the form of precipitates. For example, by adding alkaline reagents, certain metal hydroxides can be precipitated out. This step can selectively recover specific metals. After precipitation is electrolysis, metals can be extracted from the solution using electrochemical methods. The electrolysis process uses an electric current to pass through the solution in an electrolytic cell, causing metal ions to deposit on the cathode as pure metal. This method is particularly suitable for recovering high-value metals such as lithium, cobalt, and nickel. These metals are widely used in lithium-ion batteries, making chemical recovery methods particularly important in recycling lithium-ion batteries [3].

2.2.2. Advantages and Drawbacks

The advantages of chemical recovery methods lie in their high recovery efficiency, capable of effectively recovering valuable resources in batteries, especially suitable for lithium batteries and other batteries containing precious metals. Compared to physical mechanical processing methods, chemical recovery can more comprehensively extract various metal components in batteries, achieving higher recovery rates. However, chemical recovery methods also have significant drawbacks. First, the acids and bases used in the chemical recovery process are corrosive and toxic, and the process may produce toxic gases and waste liquids, posing environmental risks. If improperly handled, it can cause pollution to water sources and soil. Additionally, the operating cost of chemical recovery is relatively high, requiring the use of large amounts of chemical reagents and complex equipment, and the process is also relatively cumbersome. Therefore, in practical applications, chemical recovery methods require strict environmental protection measures and high standards of operation to reduce environmental impact.

Although chemical recovery methods have high recovery efficiency and resource utilization rates, their environmental risks and operating costs are high. Therefore, chemical recovery is usually combined with mechanical processing methods in practical applications to achieve more efficient and environmentally friendly battery recycling. The maximum recovery of valuable components in waste batteries can be achieved by comprehensively utilizing various recycling technologies, reducing resource waste and environmental pollution.

2.3. Direct Reuse

Direct reuse is a very innovative battery recycling method that focuses on material recovery and the reuse of whole batteries or parts. The core idea of this method is to directly use discarded batteries or parts in other applications rather than dismantling them into raw materials. For example, waste batteries that still have usable performance can be reassembled into new battery packs for use in electronic devices or energy storage systems with lower performance requirements. The benefits of this method are obvious. First, it can effectively extend the life of batteries, reducing resource waste. Directly reusing batteries that originally needed to be discarded can continue to be used, thereby reducing the demand for new resources. Secondly, the economic cost of direct reuse is low because it does not require complex chemical or high-energy-consuming mechanical processing. Finally, this method is environmentally friendly because it reduces the processing of discarded batteries, thereby lowering the risk of harmful substance emissions.

However, direct reuse also has its limitations. To ensure that reused batteries are safe and reliable in new applications, it is necessary to evaluate and classify discarded batteries accurately. This requires high-specification detection technologies and classification methods to determine the remaining life and performance of the batteries accurately. In addition, different types and brands of batteries have differences in structure and performance, which may face compatibility issues during reuse. Therefore, direct reuse requires high technical support and a complete evaluation system.

2.4. Comprehensive Recycling Solutions

Overall, mechanical processing, chemical recovery, and direct reuse each have their advantages and limitations. In practical operations, a combination of methods is usually needed to achieve maximum recovery and reuse of discarded battery resources. Mechanical processing methods are simple and low-cost but have limited recovery rates; chemical recovery methods have high recovery rates but high costs and environmental risks; direct reuse methods are economical and environmentally friendly but require high evaluation technologies. With the development of technology, this study needs to further research and develop more efficient, environmentally friendly, and low-cost battery recycling solutions. This not only helps in waste reuse but also achieves environmental protection, in line with global trends and requirements for environmental protection. Through continuous innovation and improvement, this study can make greater progress in the field of battery recycling and contribute to sustainable development.

3. Innovative Recycling Method Proposal

To thoroughly address the issues of environmental pollution and inefficiency in existing battery recycling technologies, this study proposes an innovative, pollution-free battery recycling method that is both highly efficient and eco-friendly. This method cleverly combines bioremediation microorganisms and nanotechnology to achieve an efficient and environmentally friendly recycling process [1,2].

3.1. Steps of Innovative Recycling Method

This method consists of three main steps: biodegradation, introduction of nanomaterials, and metal recovery and reuse.

First, in the biodegradation stage, this study can utilize specific microbial strains with metal-degrading abilities, such as Pseudomonas and sulfate-reducing bacteria. These microorganisms can secrete specific enzymes to decompose the metal compounds in batteries, allowing the metals to exist in a soluble form. The specific operational steps are as follows: after pre-treating and crushing the waste batteries into small pieces, they are soaked in a culture solution containing these microorganisms. Under suitable temperature and pH conditions, these microorganisms will decompose the metal components in the batteries into metal ion solutions through the enzymes they secrete. Compared to traditional chemical treatment methods, the biodegradation process is milder, does not require high temperatures or high pressure, significantly reduces energy consumption, and lowers pollution generated during the process. Additionally, the microorganisms do not produce harmful gases during the decomposition process, avoiding secondary pollution and ensuring environmental friendliness from the source [3].

Next, in the introduction of nanomaterials stage, this study selected special nanomaterials such as nano titanium dioxide or nano iron particles. These nanomaterials have a high specific surface area and strong adsorption capacity, enabling them to efficiently capture metal ions. The specific operational steps are adding nanomaterials to the metal ion solution obtained from the previous step. The nanomaterials, through chemical reduction and adsorption, convert the metal ions into metal elements, which then adhere to the surface of the nanoparticles. This process can be completed at room temperature and normal pressure without additional energy input, further reducing energy consumption in the recycling process. The high adsorption and reduction capabilities of nanomaterials ensure a high recovery rate of metals, making the entire process more green and environmentally friendly [4,5].

Finally, in the recovery and reuse stage, physical separation methods such as centrifugation, filtration, or magnetic separation are used to extract the metal-nanoparticle complexes from the solution. The obtained metal materials can be directly used for remanufacturing batteries or other industrial purposes, while the nanomaterials can be regenerated through specific treatment methods and recycled for the next batch of battery recycling. This process not only achieves efficient utilization of resources but also ensures the sustainability of the entire recycling system.

3.2. Advantages of Innovative Recycling Method

The core of this innovative method lies in its pollution-free, high-efficiency, and renewable characteristics. First, utilizing bioremediation microorganisms to decompose the metal compounds in batteries avoids the energy consumption and harmful gas production associated with high-temperature and high-pressure processes, fundamentally solving the environmental pollution problems of traditional recycling methods. Second, the introduction of nanomaterials improves metal recovery efficiency, making the entire recycling process more efficient. Finally, by regenerating and reusing nanomaterials and microorganisms, the method ensures sustainable resource utilization and minimizes waste generation to the greatest extent possible.

In practical applications, this method is not only suitable for recycling waste batteries but can also be extended to the treatment of other metal-containing waste, such as waste electronic products and electroplating waste liquids. Through further research and experimentation, this study can optimize the specific operational parameters of this method, improving its applicability and economic efficiency.

Overall, the innovative battery recycling method combining bioremediation microorganisms and nanotechnology provides a brand-new path for solving the environmental pollution problem of waste batteries. It not only achieves efficient, environmentally friendly, and pollution-free battery recycling but also offers an important reference for the treatment of other types of waste. With the continuous advancement of technology and the expansion of application ranges, this innovative method is expected to become mainstream in the future, making a positive contribution to global environmental protection. Through the promotion and application of this method, this study can not only effectively solve the problem of waste battery disposal but also promote the entire society towards a green circular economy and sustainable development [5].

4. Conclusions

In researching battery recycling, this study examined three primary methods: mechanical processing, chemical recovery, and direct reuse. Each of these methods has its unique principles, advantages, and drawbacks. Mechanical processing, which involves physically breaking down batteries into their component parts, is cost-effective and straightforward but has limitations in fully recovering all types of battery materials, especially rare metals. Chemical recovery, on the other hand, utilizes chemical processes to extract valuable metals from batteries, offering high recovery rates but at the cost of potentially significant environmental risks and higher operational costs due to the use of corrosive and toxic chemicals. Direct reuse focuses on repurposing whole batteries or parts, which is highly economical and environmentally friendly, but it requires sophisticated evaluation techniques to ensure the safety and reliability of reused batteries, and it faces challenges related to compatibility between different battery types and brands.

The proposed innovative recycling method, which combines bioremediation microorganisms and nanotechnology, addresses many of the shortcomings of these traditional methods. By leveraging the metal-degrading capabilities of microorganisms and the high adsorption efficiency of nanomaterials, this method achieves a high recovery rate of metals in an environmentally friendly manner. It avoids the need for high temperatures, high pressures, and toxic chemicals, thereby reducing energy consumption and preventing secondary pollution. Additionally, the regeneration and reuse of nanomaterials and microorganisms ensure the sustainability of the entire recycling process, making it a promising alternative for future battery recycling efforts.

As this study continues to use more large-scale batteries to support environmental protection initiatives, the importance of battery recycling and reuse will only increase. The key to achieving environmental sustainability and maximizing resource utilization lies in adopting comprehensive strategies that combine the best available methods with innovative technologies. Future research should focus on further improving the efficiency and environmental friendliness of these solutions, ensuring that battery recycling becomes not just a necessary process but a sustainable and economically viable one.

Policymakers, industry leaders, and research institutions must collaborate to promote the development and implementation of these advanced recycling technologies. By doing so, this study can ensure that battery recycling contributes to the broader goals of resource reuse, reduced environmental impact, and sustainable development, ultimately helping to decrease global battery waste growth and opening new avenues for the reuse of battery materials.