To study the membrane recovery and utilization of wet lithium-ion battery

As a large producer and consumer of lithium-ion batteries, China has basically formed a complete industrial chain from mineral resources, battery materials and accessories to lithium-ion batteries and terminal application products. Although the lithium-ion battery market in our country is flourishing, but our country is not a strong lithium-ion battery, the following from the lithium-ion battery diaphragm and aluminum plastic film two aspects of our shortcomings.

1 Role of lithium-ion battery diaphragm

The diaphragm is an important part of the lithium-ion battery. It is located between the positive and negative poles inside the battery, ensuring that lithium ions pass through while blocking the transmission of electrons. The performance of the diaphragm determines the interface structure and internal resistance of the battery, which directly affects the battery's capacity, circulation, and safety performance. The excellent performance of the diaphragm has an important role in improving the comprehensive performance of the battery.

The requirements of lithium-ion batteries for the diaphragm include:

(1) It has electronic insulation and guarantees the separation of positive and negative poles;

(2) Have a certain aperture and porosity, ensure low resistance and high Ionic conductivity, and have good penetration of lithium ions; (3) Electrolytic corrosion resistance, with sufficient chemical and electrochemical stability, due to the fact that the solvent of the electrolyte is a highly polar organic compound;

(4) It has good infiltrability of electrolyte and strong moisturizing ability of suction liquid;

(5) High mechanical stability, including puncture strength, tensile strength, etc., but the thickness is as small as possible;

(6) Good spatial stability and integrity;

(7) Good thermal stability and automatic shutdown protection performance;

(8) The heat reduction rate is small, otherwise it will cause a short circuit and cause the battery heat to lose control. In addition, power cells usually use composite membranes, which require higher requirements for the diaphragm.

Aluminum battery diaphragm:

Role of Aluminum Plastics in Lithium-ion Battery

Aluminum plastic film is one of the five major materials for lithium ion batteries and is a flexible lithium battery packaging material. The aluminum plastic film consists of an outer nylon layer / binder / middle layer aluminum foil / binder / inner layer hot seal layer, a total of five layers, each layer of functional requirements are relatively high.

Requirements of Lithium-ion Battery for Aluminum Plastics

The barrier, puncture resistance, electrolyte stability, high temperature resistance and insulation of aluminum plastic film affect the performance of lithium-ion batteries. Any loss in any aspect may lead to a reduction in battery performance and direct scrapping. Aluminum plastic film is produced by precision coating technology. At present, Japanese companies have the most advanced precision coating technology in the world.

3 Lithium-ion battery aluminum plastic film process

Dry and hot process is the main production process of aluminum plastic film. The dry process is made by directly pressing aluminum and polypropylene with an adhesive bond, and the hot process is made by using MPP between aluminum and polypropylene and then slowly heating up.

The aluminum plastic film produced by dry method is thin, has a good appearance, has excellent deep flushing performance and anti-short circuit performance, and the process is simple and low in cost. However, compared with the heat method, the electrolytic liquid and water resistance are poor. The advantages of the heat method are good in electrolytic fluid resistance and water resistance, but the deep flush molding performance and short-circuit protection performance are not as good as the dry method, and the appearance and cutting property are poor.

The wet diaphragm has become the mainstream route for the next five years:

In 2016, four of the world's top four lithium diaphragm companies, Japan's Asahi, Japan's Toray, Celgard and South Korea's SKI, accounted for 20.8 %, 15.1 %, 10.8 %, and 9.6 % of the global market share, respectively. The top four diaphragm companies accounted for nearly 50 % of the share. At present, the global manufacturers of diaphragm are mainly wet methods. The price of wet diaphragm is relatively expensive. In the future, wet diaphragm will still take the high-end market route in power batteries, while the low-end power batteries will still be dry.

The wet diaphragm production process is divided into six major systems: feed and feed system, extrusion mixing system, casting cooling system, stretching system, winding system and washing drying system. Each system needs higher precision guarantee in operation, and the lack of precision control ability causes the uneven thickness of wet diaphragm, the difficult appearance of micro porous state, and the increase of porosity, resulting in the difference of diaphragm consistency. Therefore, the degree of precision control of the wet diaphragm process is also of great importance.

During the coating process used in the wet diaphragm production of lithium batteries, there will be different degrees of environmental pollution in the coating process, mainly air pollution, and the main pollutants of the gas are "organic volatiles". The English abbreviation is VOC(mainly including isopropanol, benzene, toluene, xylene, ethyl acetate, alcohol, acrylic acid, heavy metal silver ions, acetone, etc.), which is an organic compound that reacts with nitrogen oxides in the sun's ozone layer., VOC volatilization into the air, combined with fine dust particles and other substances in the dust, will form gray fog, stimulate the lungs of the human body, and have a negative impact on various biological health such as animals and plants.

At present, there are many wet diaphragm production technologies in domestic enterprises, but one drawback of wet diaphragm production technology is that environmental pollution is serious, especially in the washing and drying process of wet diaphragm production process will produce a large number of VOCs enterprises. In recent years, the government's environmental protection requirements have become more and more strict. Therefore, many lithium battery wet diaphragm manufacturers face more and more environmental protection standards.

Standard Group adopts Japan's advanced VOCs treatment process, which can effectively solve the environmental pollution problem during the production of lithium battery wet diaphragm. The general conventional treatment methods are:

Brief description of the treatment process:

A process such as regenerative oxidation, wheel concentration + RTO / RCO \ activated carbon adsorption can generally be considered to prevent pollution gas emissions.

Huashijie offers you the best value for money solutions based on years of deep mining and successful waste gas management

Recommended: sorption recovery + heat storage oxidation + residual heat recovery treatment technology

1, adsorption recovery

Huashijie adsorption and recycling equipment, relying on the strong scientific research team and the technical support of research institutes of major institutions, has self-developed adsorption materials, and has rich project design and implementation experience in the industry.

1 The technology of adsorption and recovery of activated carbon fiber is a method for the recovery and treatment of pollutants in exhaust gas using the adsorption and desorption properties of adsorption materials. It can be used in the treatment of medium and low concentrations of 1000-10000m? / H Ventilation of organic exhaust gas.

The adsorption and recovery technology of activated carbon particles is a method for the recovery and treatment of pollutants in waste gas by the adsorption and desorption of adsorbed materials. It is generally used for the treatment of high concentrations of organic exhaust gas.

2, regenerative oxidation

1 bed regenerative oxidation

The exhaust gas is heated to 760 °C for direct combustion, or heated to 300 °C for catalytic combustion, so that the VOCs in the exhaust gas are oxidized and decomposed into CO2 and H2O, and the high-temperature gas generated by oxidation flows through the ceramic heat storage body to heat it up. "Reheat", And used to Preheat the subsequent entry of organic exhaust gas, thus saving the waste gas warming fuel consumption treatment technology.

2 Rotation regenerative oxidation

Product characteristics:

Special adsorption material, higher adsorption capacity

Negative pressure + steam desorption, reduce running energy consumption

Controlling Coagulation Temperature and Saving Energy Consumption of Waste water Treatment

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