Analysis of the development situation of power battery technology

　　1. The current technology maturity of ternary and lithium iron phosphate batteries is high

　　1. Ternary and lithium iron phosphate batteries are the focus of corporate layout

　　In the field of automotive power batteries, lithium batteries have become mainstream. At present, the main battery types of international mainstream power battery companies are basically lithium iron phosphate and ternary lithium batteries.

　　From the perspective of the Chinese market, lithium iron phosphate and ternary batteries are still the mainstream of vehicle power batteries, with installed capacity accounting for 94.5% and 93.3% of the total market in 2016 and 2017.

　　2. Lithium iron phosphate and ternary lithium batteries still have a period of development.

　　After a period of development, the technical level of lithium iron phosphate and ternary lithium batteries has been significantly improved. In terms of cost, the price of lithium iron phosphate battery packs dropped from 1.8-1.9 yuan/Wh at the beginning of 2017 to 1.45-1.55 yuan/Wh at the end of 2017. The price of ternary power battery packs dropped from 1.7-1.8 yuan/Wh at the beginning of the year to 1.4-1.5 yuan/Wh at the end of the year.

　　In terms of energy density, at the end of 2017, the energy density of battery cells based on NCM622 materials exceeded 200Wh/kg, and the system energy density was 160Wh/kg. In 2018, the energy density of battery cells is expected to reach 230~250Wh/kg.

　　There is still room for improvement in these two types of batteries, especially the improvement of battery performance by new generation materials, such as the research and development of cathode material 811 and silicon carbon anode, which will further increase the energy density of lithium power batteries. The single energy density is expected to be Reaching 300Wh/kg, coupled with the strong foundation of these two battery industries, competition in the industry will still exist for a certain period of time.

　　2. Solid-state batteries have become the focus of current layout

　　From the perspective of technical potential, the theoretical energy density of lithium iron phosphate system is about 170Wh/kg, and the theoretical energy density of ternary lithium battery is 300-350Wh/kg. At the same time, there are safety issues such as low thermal decomposition temperature and easy combustion and explosion. The space for energy density improvement is relatively small. However, all-solid-state lithium batteries have great potential to increase energy density and are theoretically more feasible.

　　1. Potential technical advantages of solid-state lithium batteries

　　The biggest feature of solid-state lithium batteries compared with traditional lithium batteries is that they use solid electrolyte materials. When the electrodes and electrolyte materials used are solid and do not contain any liquid components, they are all-solid-state lithium batteries. Solid electrolytes have changed the traditional structure of lithium batteries. Separators, liquid electrolytes, etc. are no longer necessary components, bringing huge potential for technological advantages.

　　The main technical advantages of solid-state lithium batteries are: first, they are highly safe, do not contain flammable, volatile and toxic organic solvents, and have no leakage problems. They are expected to avoid the generation of lithium dendrites and greatly reduce the risk of battery combustion and explosion. risk. The second is the long cycle life. There is no problem that the liquid electrolyte produces a solid electrolyte interface film during the charge and discharge cycle. The expected life span currently developed is 15,000-20,000 times. Third, the energy density is high. In traditional lithium batteries, the separator and electrolyte account for 40% of the volume. Solid electrolytes can significantly reduce the distance between the positive and negative electrodes of the battery and increase the volume specific energy. The maximum potential energy density of all-solid-state lithium batteries is estimated to be 900Wh. /kg. Fourth, the system has a high specific energy density, and the solid electrolyte has no fluidity, so it can be connected in series to form high-voltage cells, which is beneficial to improving the efficiency and energy density of the power battery system. Fifth, the selection range of positive and negative electrode materials is wide, and new technologies such as metallic lithium negative electrodes and high-potential positive electrode materials can be used at the same time. All-solid-state metallic lithium batteries are the research and development direction of new batteries in the future. In addition, solid-state batteries have a wide operating temperature range and electrochemical stability window, and have the potential to be thinned and flexible.

　　2. Global companies are deploying solid-state batteries to compete for opportunities.

　　Due to the current bottlenecks of lithium iron phosphate and ternary lithium batteries, as well as the potential advantages of solid-state batteries, many companies in the industry chain involving power batteries, automobiles and energy in Europe, the United States, Japan, South Korea, China and other countries are actively deploying and developing solid-state batteries. Battery.

　　Generally speaking, European and American countries are mainly entrepreneurial companies based on solid-state battery technology, while Japan mainly focuses on battery technology innovation by traditional car companies and machinery companies. Chinese companies entered the field of solid-state lithium batteries relatively late, and are mainly supported by scientific research institutions or universities, and the industrialization process is slow.

　　3. Technical and industrial barriers need to be broken through urgently

　　Through the research of enterprises and research institutions, solid-state battery technology has achieved breakthroughs, with energy density exceeding 300Wh/kg. However, they are basically laboratory products and are still far away from industrialization.

　　At the technical level, solid electrolyte ionic conductivity, solid/solid interface compatibility and stability are still two major constraints. The conductivity of polymer electrolytes is low at room temperature and generally needs to be heated to above 60°C to work properly. For example, Bolloré in France uses a technical route of polymer electrolytes and battery heating; the conductivity of sulfide electrolytes is currently at the same level as traditional lithium batteries Quite, but it is still necessary to break through the interface phase problem, mainly through material synthesis and nanolayer technology to increase the amount of active substances and reduce the interface layer resistance. At the same time, metallic lithium anodes and new composite cathode materials are still under development, and are expected to realize the application of all-solid-state lithium metal batteries. By then, there will be huge breakthroughs in energy density, capacity, rate performance, safety performance and cycle life.

　　At the industrialization level, the dilemma of failing to achieve large-scale production mainly lies in production equipment, production technology and production line environment. For example, the lamination, coating, and packaging processes in solid-state battery preparation require customized high-precision equipment, and the production line environment also needs to maintain a higher level of drying room. Only when large-scale production achieves an increase in output and capacity can the cost of solid-state lithium batteries be reduced.

　　Overall, the production and preparation maturity of solid-state lithium batteries still needs to be strengthened, and large-scale and automated production lines need further research and development. It is still in the industry accumulation period. The overall development path of solid-state batteries is that due to the stability problem of solid/solid interface, the content of liquid electrolyte gradually decreases, and the transition from liquid → semi-solid → solid-liquid hybrid → solid state → all-solid-state battery; in the development of all-solid-state lithium metal batteries, Due to the rechargeability problem of metallic lithium anode, the anode material will transition from graphite → alloyed anode (such as Si/C) → metallic lithium anode. With the development of R&D technology and industrial production, the performance and production of solid-state batteries will be gradually optimized, ushering in opportunities in the power battery market.

　　3. Potential technology substitutes still exist

　　In addition to the improvement of current lithium batteries and the layout of solid-state batteries, domestic and foreign companies and institutions/universities have made different attempts in power battery technology innovation. Some indicators have been greatly improved compared with the current level, providing opportunities for improving the performance of power batteries. A powerful reference.

　　By sorting out the technical indicators of typical innovation cases collected, it can be found that the key indicators of some products have been improved. In terms of energy density, the energy density of aluminum-air batteries reaches 780Wh/kg, lithium-sulfur batteries reach 350Wh/kg, and solid-state batteries reach 360Wh/kg; in terms of charging rates, the maximum charging rate of typical innovative products has exceeded 100C. In terms of cycle life, typical innovative products can already exceed 15,000 times.

　　New batteries have many advantages. First, in terms of technology, for example, lithium-sulfur batteries use sulfur as the cathode material, and the theoretical specific energy of the battery can reach up to 2600Wh/kg. Lithium-air batteries are also a very potential high-specific-capacity battery technology. The reversible reaction of lithium metal and oxygen has a theoretical upper limit of energy density of 11,000Wh/kg. Second, the industry can reduce its dependence on scarce resources. For example, sodium-ion batteries have the advantages of abundant reserves and lower costs than lithium-ion batteries.

　　However, current innovative power battery products are generally laboratory products, and new batteries still face many challenges in the next step of industrialization. For example, lithium-sulfur batteries have low safety, low volume specific energy, low discharge rate, low energy conversion efficiency and low cycle times, making it difficult to be applied in the automotive field in a short time. In general, although these studies are currently in the experimental stage and are far away from industrialization, whether they can replace existing system batteries in a certain period of time is also controversial in the industry. But there is no doubt that these batteries are expected to break some of the current technical bottlenecks of power batteries, reduce battery costs, and create longer cruising ranges. In the development process of the power battery industry, these batteries cannot be ignored.

　　4. Summary

　　From the perspective of technological development, currently ternary and lithium iron phosphate batteries have dominated the automotive power battery market. Ternary and lithium iron phosphate batteries have become the main technical routes of mainstream companies, and companies are further deploying these two technical routes. From a development perspective, ternary and lithium iron phosphate battery technologies have made breakthroughs, but there is still room for further improvements in technology, and industrial competition will continue for some time.

　　From the perspective of new battery technology layout, solid-state batteries have technical advantages and can solve many problems faced by the current industry. Domestic and foreign companies are rushing to lay out and achieve technological breakthroughs. However, from the perspective of industrial development, solid-state batteries are now in the industry accumulation period, and there are still many technical and industrial supporting issues that need to be solved urgently.

　　On the other hand, in addition to the improvement of current lithium batteries and the layout of solid-state batteries, many research institutions are also developing new generation batteries such as lithium-sulfur and lithium-air batteries, and have made breakthroughs in certain technologies, providing opportunities for the development of the battery industry. Favorable reference. But in general, these studies are basically in the experimental stage, far away from industrialization, and there are many controversies in the industry. However, it is undeniable that these batteries are expected to break some bottlenecks of current power batteries and are still in the process of industrial development. Can not be ignored.

　　While battery companies are improving the performance of existing technology products, they should also actively develop the research and development of next-generation batteries in order to dominate the next round of competition. Government departments should encourage enterprises, research institutions and universities to develop key materials, battery cells and system key technologies for power batteries through various channels such as science and technology plans (special projects, funds), relevant innovation projects and high-tech industry development projects. Research and development, and actively promote the engineering and industrialization of key technologies and equipment such as the preparation, production process, and testing of new products and new materials such as solid-state batteries, lithium-sulfur batteries, and metal-air batteries, promote the construction of engineering technology capabilities across the entire industry chain, and Promote the application of new power battery technologies and products in demonstration and promotion projects.

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