How is the development of power lithium battery system going?

Lithium electricity industry absorb billions of gold, golden compass point to where, the 2018 China international lithium electricity and electric technology development peak BBS, on April 20-21, held in Shanghai, the conference by: the first lithium power grid, the first electric Shared, China charging pile network, lithium electricity c, jointly organized by He Li exhibition, at the same time, China's international electric cars and filling in electrical technology peak BBS, share more than 40 guests to attend the speech at the conference, more than 500 guests to attend, at the same time, more than 20 companies set up a booth on new technology and products.

Hello, everyone. Today, Ms. Wang and I have arranged for her to attend the brics lithium battery summit and present the PPT. My topic today is the development trend and direction of power battery system for pure electric vehicles. First, the requirements for power batteries of micro pure electric vehicles; second, the difficulties and pain points in the development; third, the development trend and prospect at last.

The first thing that we want to develop a good system, we first need to learn the user's concerns and pain points, we think the battery system focus mainly on three sides, costs and life, life contains really can reach 8 years guarantee of 12 km, security include collision, squeezing, soak can achieve this standard, the last is life, life of anxiety is pure electric vehicles so far. The following 10 dimensions are used to evaluate the battery system.

First of all, the structure of the safety cost of batteries, battery life, reliability evaluation of 10 aspects, such as it, battery performance of high and low temperature environment, you fill in the process of electricity, with the core of the team, whether to understand the strategy of BMS, and demand for cars and requirements, and finally PACK integration capabilities, consistency consistency is mainly in the electric car after the end of life whether it can meet the design requirements, this is very difficult to do so far. Then how can we transform the demand of the whole car into the requirements of the battery system? The comparison table between the performance of the whole car and the battery performance is shown as follows: first, the specific energy of the load corresponds to the specific power; start-up and climbing are the specific power; charging time is the charging ratio; the power loss and discharge rate of the stop; energy reflects the replay efficiency; and finally, the price. Different cars have different requirements for us. To ensure new energy and safety, our depth is 90%, that is, the head and tail are 5%, so that we can give full play to our performance and function in a safe and economic environment with maximum efficiency.

Here are the pain points and difficulties of the second development. This picture is the development process of our vehicle. Each subsystem process will take precedence over the parent system, so as to ensure the consistency in the development process. In the development stage, there are four stages, ABCD sample.

In A sample is critical at this stage, mainly reflected in the function of the input stage, we complete the input and the establishment of the basic performance, the establishment of the PACK, and the establishment of hardware, at this stage is mainly manifested in the late we design process, whether there is sufficient consideration and related functions, that is embodied in vehicle platforms and development needs, in sample B, A kind of stage design is done, enter the B sample, sample B is to design the optimization of the car, at this stage to reflect on the design of A kind of incomplete place, put it to the optimization of the mature, battery system at this stage is to complete the DV test, Next is C phase, more concern is testing, at this stage for the inside of the BMS and device requirements for the degree of order of magnitude, which focus on the abuse test, electric performance test environment test and high and low temperature, the last is D, D is the process of the research stage to production stage, this process is embodied in the process as well as the durability test, provide data support for the later listed and reference.

At the same time, we will analysis process at each stage of development, establish a safe, efficient, standardized, modular, platform of power system, at each stage of the process we will be in accordance with the process development again, in the development process, we will have an ID, this ID is unique, and we will be late from concept development to verify is the ID number back in full, so we in the process of our overall design can ensure the effectiveness of function, integrity, prevent loss of the future.

We have just talked about the vertical development process, but now we will introduce the horizontal development process. In the whole battery system development process, we will have five modules to progress at the same time, mainly including system, structure, BMS, thermal management, testing and joint adjustment.

To introduce the following know beans in the three stages of planning, at this stage we have completed the first stage to 2017 compared with modern design, we can already do 150 wh/KG, our level of protection required is currently S67, to 2020, we adopt a more integrated design and requirements for protection the we will gradually achieve S68, this system is the lowest, the battery system is also very important, in the process of development in the future, will gradually turn protective level gradually improve, hereafter have program could meet the requirements of the first match. In the third stage, we may adopt integrated design and introduce the application of emerging materials such as carbon fiber. Our goal is to achieve 250WH/KG by 2025, and we will also introduce liquid cooling management. These are some of the design principles used throughout the battery system development process. The focus is still including several aspects, one is the design of the box, functional safety definition and various tests. Now let's introduce some advantages and disadvantages of our existing box structure.

The advantages of plate gold welding box are simple structure and low cost. The disadvantage is very obvious, heavy quality, scale production is difficult, the most important point is the anti-corrosion is not easy to do, very easy to corrosion and rust. Followed by the design of the enclosure and SMC, obvious effects of the box body is lightweight, good heat dissipation, large-scale production, the second to process to increase working hours, in the finish machining for secondary processing, aluminum box very occupied working hours, it is much thicker than the other three cabinet, such intangible occupies a space, this is very deadly for electric cars. The following is an introduction to high strength integral stamping. The stamping in the automotive industry is very mature, it's easy to forming, the implementation, is suitable for mass production, then the composite material, compared advantages will be more, can adapt to different models of different requirements, can be a development, at the same time, heat preservation performance is good, suitable for production, there is a same weakness is development cycle is long, the mould cost is high.

Battery thermal management, then the battery thermal management we focus on the two points, one is online, one is offline and online for battery system within the range of 35 to 55 degrees of work, the interval according to the battery material system according to the differences of different design have different, we are mainly in charge of 2 hours from 20 degrees below zero to five degrees of heating process, in the process of 10 hours, to complete the process of charging.

The following is the focus of BMS design and our vehicle. Our vehicle pays more attention to the content of fault treatment. Now the design is very realistic. So far certainly to the car first, personal safety first. The BMS that we are most concerned about now requires that electronic components must be used in the design of BMS. However, we need to ensure that high temperature and low temperature will not cause failure, and many BMS cannot meet this requirement.

According to the definition of EVCARD, we divide the security objectives into five levels, and decompose them into five levels in the process of system design. We will decompose the electrical security, functional security and other aspects, and finally embody them into my five levels through the perfection of the subsystem.

The following is the development trend and prospect of power battery system. This is the current plan of our company till 2030. The system can reach 1 yuan per watt-hour in 2020 and 350WH/KG in 2030 with the cost less than 0.7 yuan per watt-hour. This is a trend brought about by Mr Oseki, a Japanese expert. By 2030, the cost of power batteries in Japan will have fallen to 30% of their current cost, while the specific energy of the cells will reach 700WH/KG. In addition, wireless charging technology has also done a lot of work in this regard. We can see that in the near future, electric cars with wireless charging function will achieve convenient and efficient charging.

In addition, the application of big data in our design process. At present, we know that the total number of vehicles in the market is more than 40,000 to 50,000. In the field of data processing, we are also very concerned about it.

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