Discuss the technical development trend of soft pack power lithium battery

The development trend of new energy vehicles in the future is electrification, intelligence, networking, lightweight, and sharing. These five modernizations will definitely put forward higher requirements for power lithium batteries. What will the future power lithium batteries look like?

This is the current application status of power lithium batteries. At present, lead-acid batteries are mainly used in the start-stop power supply of some low-speed vehicles and cars. Lead-acid batteries are cheap, but have a very low energy density. Nickel-metal hydride batteries are mainly used in Japanese hybrid vehicles and energy storage, because the energy density of nickel-metal hydride batteries is a little higher than that of lead-acid, and the price is a little cheaper than lithium-ion batteries. With the development of new energy vehicles, the energy density and life of power lithium batteries are required to be higher, so lithium-ion batteries are currently the mainstream power lithium batteries, widely used in HEV, PHEV, BEV, FCV, etc.

This is the development plan proposed by the three development departments of our country for lithium-ion batteries. From the three plans, high-energy-density batteries are the future development direction. They all require the energy density of batteries to reach 300Wh/Kg in 2020, and strive to achieve 350Wh/Kg also puts forward higher requirements on the cost and the energy density of the battery system. I will not describe them here one by one. You have seen many of them before.

This is the country's subsidy policy in 2018, which you should know very well. I just made a summary of the 2018 subsidy policy. First, in terms of cruising range, the longer the cruising range, the more subsidies; second, encourage car companies to develop models with higher cruising range, and cancel subsidies for cars with a cruising range of less than 150 kilometers; third, the battery system requires higher energy density. Because the mileage requirements are higher.

In the lithium battery industry, China, Japan and South Korea are three pillars, competing in terms of battery energy density and cost. Korean companies have expanded their production on a large scale in my country. The table shows the research progress of Japanese and Korean companies’ high-energy-density batteries. At present, the energy density of Japanese and Korean batteries is above 250Wh/Kg, which is comparable to the domestic level. It is also consistent to achieve the goal of 300Wh/Kg in 2020. The current research and development level is at the same level, but safety research needs to be strengthened. LG said at the beginning of this year that it will release a NCM811 system battery, but mass production has been postponed.View more details:72v 200ah lithium battery pack

To improve the energy density of a single battery, a new electrochemical system must be developed. In 2017, the 170~220Wh/kg electrochemical system is lithium manganese oxide, lithium iron phosphate, medium nickel ternary, lithium manganate doped medium nickel ternary pair Graphite system, 240~260Wh/kg electrochemical system in 2018 is medium-high nickel ternary, lithium manganate doped medium-high nickel ternary pair silicon carbon or silicon oxygen negative electrode, in 2020 the electrochemical system above 300Wh/kg should use high nickel , Lithium-rich manganese-based positive electrode, high-voltage lithium manganate to silicon carbon or silicon oxygen negative electrode.

In response to the needs of large-scale energy storage and the rapid development of electric vehicles, high specific energy, high power, long life and low cost key materials and their preparation technologies are important directions for the development of lithium-ion batteries, energy density, life, cost, and safety. Indicators should be taken into consideration. High specific energy is the unremitting pursuit of the lithium battery industry. In 2016, 2022, and 2025, these indicators will be greatly improved. In the future, we will not have to worry about the energy density, lifespan, and safety of power lithium batteries.

At present, there are three mature packaging methods for power lithium batteries, soft pack, square, and cylinder. The three packaging forms of batteries have their own advantages and disadvantages. Comparing the three, soft pack batteries have high specific capacity, good safety, long cycle life, small internal resistance, and flexible design, but poor consistency, high cost, and prone to accidents. Leakage. Due to the low degree of automation of soft-pack lithium-ion battery equipment in the past few years, the consistency will be poor, but at present, domestic and foreign equipment companies have increased investment in research and development. The third factory of Thornton New Energy Company currently has an automation degree of more than 90% of the lithium-ion battery production line equipment, and the consistency has been better resolved. Soft-pack batteries will be the future development trend.

The second part introduces the technical characteristics of the pouch battery. Under the same capacity, the pouch battery has the smallest weight and volume; under the same volume, the pouch battery has the highest capacity. Under other conditions being the same, the pouch battery has the highest volumetric energy density and mass capacity density compared to aluminum shells and cylinders. At present, our data comes from Gaogong lithium battery.

At present, it is important to further improve the energy density of the battery system from the aspects of battery cell design, module, and Pack lightweight. Since 2017, domestic mainstream battery factories have increased their ternary layout, and now high-nickel, high-voltage ternary and silicon carbon are the mainstream technical routes. From 200-280, change positive electrode, from low nickel to high nickel, or low pressure to high pressure; 280-300, change negative electrode, from graphite to silicon carbon; 300-350, ternary change to lithium-rich manganese base; above 350, or change The electrolyte changes from liquid to solid, or replaces the lithium-ion battery system, and develops lithium-sulfur batteries or all-solid-state batteries.

Pack is lightweight and can do the job in many ways. Some lightweight materials can be used, some designs can be optimized, and some simulations can be done in advance with the assistance of CAE. In terms of batteries, you can choose some batteries with high energy density and standardized battery size. For example, the 100302 battery meets both the national standard and the VDA size. You can also optimize the design of the box and modules. In addition, some optimization can also be done in manufacturing engineering and structural design. Pack lightweight is also the future trend.

This is the data of the energy density of the pouch battery system equipped with the mainstream models of some first-class foreign OEMs in recent years. These models mainly use soft-pack batteries. Hyundai has two vehicles equipped with LGC's NCM811 system batteries this year. Mass production of this battery has reportedly been delayed. There may be three reasons for my personal analysis: First, the manufacturing cost of NCM811 materials and batteries is high. Although the content of cobalt is reduced, the manufacturing process is complicated and requires high environmental humidity; second, the thermal stability of NCM811 materials is relatively low. Poor, resulting in low safety of NCM811 system batteries; Third, the cycle life of NCM811 system batteries is short, which may not be able to meet the needs of the entire vehicle.

According to our statistics on the accident rates of different types of batteries, in 2016-17, there were 29 and 16 domestic new energy vehicle fire accidents respectively. In terms of matching models, square battery accidents are relatively high, both the number of accidents and the number of vehicles accounted for more than half; in the first half of 2018, a total of 8 cases occurred in China, half of which were square and half cylindrical; according to statistical data, soft pack batteries Security is relatively the highest. The soft-pack lithium-ion battery uses aluminum-plastic film as the packaging shell. In the event of a safety hazard, the soft-pack lithium-ion battery will only burst open and release energy from the seal, unlike the steel-cased aluminum-cased lithium-ion battery. In that way, there will be a large internal pressure and an explosion will occur. At present, most of the soft-pack lithium-ion batteries still use liquid electrolytes, and a few use gel-state electrolytes. With the development of energy density, the development of solid-state lithium-ion batteries is an inevitable trend, and the safety of lithium-ion batteries will be further improved.

We also made statistics on the cost of different types of batteries. In terms of packaging costs, the packaging costs of cylindrical, square, and soft packs are similar, with little difference. But in terms of the composition of packaging materials, the cost of the square aluminum shell is the highest. In order to reduce the cost per Wh of the square aluminum shell, the battery capacity must be increased, but as the cost decreases, the safety will also decrease, and it may be hot. Out of control, there are some heat transfer speeds in the middle that will be limited. The cost of packaging materials for soft-pack batteries with different capacities is similar, and it is relatively more difficult to reduce the cost per unit watt-hour. The capacity of the pouch battery is generally around 50~60Ah.

We analyzed the weight and cost ratio of each component of the pouch battery. It is found that the weight of aluminum-plastic film accounts for 3.0%, but the cost accounts for 8% of the total cost of the entire lithium-ion battery. It occupies the third place in the cost structure, and the cost accounts for a large proportion. This is mainly due to the preparation process and market conditions of the aluminum-plastic film. At present, more than 90% of the aluminum-plastic films used in domestic soft pack power lithium batteries are imported.

Here is a brief introduction to the aluminum-plastic film structure. Aluminum-plastic film is mainly composed of three layers: outer nylon layer, middle aluminum layer, and inner CPP/PP layer. Special aluminum layer and CPP/PP layer have high technical barriers and strict product requirements. The global aluminum-plastic film market is still dominated by Japan and South Korea. The company is monopolized, and the two giants of Japan DNP and Showa Denko have a combined market share of more than 70%. DNP and Showa Denko are representative companies of the thermal method and the dry method, respectively.

The common technical problems encountered by domestic aluminum-plastic films are that the domestic aluminum foil has defects in surface treatment and poor stability. In addition, the CPP layer material has not been completely overcome, and there are problems in insulation and high temperature resistance. In recent years, domestic aluminum-plastic film companies have been constantly improving and updating materials, technology, equipment, etc., and have qualitatively improved product quality, product consistency, and electrolyte resistance. ATL, Coslight, etc. have begun to apply digital domestic aluminum-plastic films in batches; at the same time, in the field of power lithium batteries, Selen Technology has successfully introduced aluminum-plastic film products into domestic power lithium battery companies through the acquisition of Japan's T&T's mature aluminum-plastic film factory and patented technology . The localization of domestic companies has become unstoppable through the development of endogenous breakthroughs in technology, introduction and absorption, and extensional acquisitions.

After the localization of aluminum-plastic film, the cost of soft-pack power lithium batteries will be reduced. Domestic aluminum-plastic film companies include Selen Technology, Zijiang Company, Dao Ming Optics, Foster, etc. After the localization of aluminum-plastic film, the cost of aluminum-plastic film is reduced by 5-7 yuan per square meter, and the overall cost of soft-pack power lithium batteries is reduced by about 1.5%, which can accelerate the increase in the market share of soft-pack batteries in the new energy vehicle market.Also read:eve lifepo4

The third part introduces the marketization trend of pouch batteries. The output of the three types of batteries accounted for a large proportion, among which square shell batteries accounted for a large proportion. With the characteristics of high energy density, good safety performance and flexible design, soft-pack batteries are expected to accelerate the penetration rate of soft-pack batteries in the new energy vehicle market. At present, the market share of pouch batteries in new energy passenger vehicles is still relatively high. This is the proportion of the number of global new energy passenger vehicles (top20) equipped with batteries of different structures in 2017 according to the statistics of Gaogong Lithium Battery. Among them, soft pack batteries accounted for 37.4%, higher than square aluminum shell batteries (32.8%); The proportion of the number of new energy passenger vehicles (top20) in my country equipped with batteries of different structures in a year, of which soft-pack batteries accounted for 44.9%, which is slightly lower than that of square aluminum-case batteries (48.7%). It is estimated that the demand for power lithium batteries of ternary materials will rise to 71.6GWh in 2020, accounting for about 50% from the current 22%. For ternary power lithium batteries, the use of soft pack batteries accounts for a large proportion.

According to the data of Gaogong Lithium Battery, the demand for power soft pack batteries in 2017 was 6.5GWh, and the market penetration rate was 12%. The industry expects that the demand for power soft pack batteries will reach 10.9GWh in 2018, with a market penetration rate of 14%; in 2020, the market demand will reach 79.4GWh, and the penetration rate will increase to 40%. Reasons: First, the market demand for high-energy-density batteries, to achieve the target of 300Wh/kg batteries, only soft packs can be used. Lishen, Guoxuan, and CATL already have soft pack wires; second, lithium-sulfur batteries and all-solid-state batteries , as far as the current process, equipment, and structural design are suitable for the soft-pack battery route; third, safety issues, soft-pack batteries are relatively safer.

The fourth part introduces our Thornton New Energy Company. Thornton New Energy Company is affiliated to Sound Group. Our Sound Group was established in 1993. At present, our business covers water resources, water ecology, solid waste treatment, sanitation, renewable resources, new energy, etc. Our group is currently holding Participated in 2 listed companies, one is Sound International and the other is Tus-Sound. The brand value of Sound has reached 15.2 billion, and the group's total assets are more than 40 billion. Our group has made a layout in the new energy industry, and the layout is relatively complete, including batteries, motors, electronic controls, energy storage, charging piles, and new energy vehicles. And our Thornton New Energy has also formed a relatively complete industrial layout in the battery sector.

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