I. Current ternary and lithium iron phosphate battery technologies are highly mature.
1. Ternary and lithium iron phosphate batteries are the company's key focus.
In the field of automotive power lithium batteries, lithium-ion batteries have become the mainstream. Currently, the main battery types of major international power lithium battery companies are lithium iron phosphate and ternary lithium-ion batteries.
In the Chinese market, lithium iron phosphate and ternary lithium batteries are still the mainstream power lithium batteries for vehicles, accounting for 94.5% and 93.3% of the total market in 2016 and 2017, respectively.
2. Lithium iron phosphate and ternary lithium-ion batteries still have a period of development ahead.
After a period of development, the technological level of lithium iron phosphate and ternary lithium-ion batteries has been significantly improved. In terms of cost, the price of lithium iron phosphate battery packs decreased from 1.8-1.9 yuan/Wh at the beginning of 2017 to 1.45-1.55 yuan/Wh by the end of the year. The price of ternary lithium-ion battery packs decreased from 1.7-1.8 yuan/Wh at the beginning of the year to 1.4-1.5 yuan/Wh by the end of the year.
In terms of energy density, by the end of 2017, the energy density of single cells based on NCM622 material exceeded 200Wh/kg, and the system energy density was 160Wh/kg. It is estimated that the energy density of single cells will reach 230~250Wh/kg in 2018.
Both types of batteries still have room for improvement, especially with the application of next-generation materials to enhance battery performance. For example, the development of 811 cathode material and silicon-carbon anode will further improve the energy density of lithium-ion batteries, with the single-cell energy density expected to reach 300Wh/kg. In addition, given the strong industrial foundation of these two types of batteries, competition in the industry will continue for some time.
II. Solid-state batteries have become a key focus of current investment.
From a technological potential perspective, the theoretical energy density of lithium iron phosphate batteries is approximately 170 Wh/kg, while that of ternary lithium-ion batteries is 300-350 Wh/kg. Both also suffer from safety issues such as low thermal decomposition temperatures and susceptibility to combustion and explosion, limiting the potential for energy density improvement. However, all-solid-state lithium-ion batteries possess significant potential for energy density enhancement and are theoretically more feasible.
1. Potential technological advantages of solid-state lithium-ion batteries
The most significant difference between solid-state lithium-ion batteries and traditional lithium-ion batteries lies in their use of solid-state electrolyte materials. When both the electrodes and electrolyte materials are solid and contain no liquid components, it is called an all-solid-state lithium-ion battery. Solid-state electrolytes have changed the traditional structure of lithium-ion batteries, making separators and liquid electrolytes no longer necessary components, thus bringing enormous technological advantages and potential.
The key technological advantages of solid-state lithium-ion batteries are as follows: First, they offer high safety, as they contain no flammable, volatile, or toxic organic solvents, eliminating leakage issues and potentially preventing lithium dendrite formation, thus significantly reducing the risk of battery combustion and explosion. Second, they boast long cycle life, avoiding the solid electrolyte interface film problem that occurs with liquid electrolytes during charge-discharge cycles; the expected cycle life is currently 15,000-20,000 cycles. Third, they exhibit high energy density; in traditional lithium-ion batteries, the separator and electrolyte account for 40% of the volume, while solid-state electrolytes can significantly reduce the distance between the positive and negative electrodes, increasing volumetric energy density. The estimated maximum potential energy density of all-solid-state lithium-ion batteries reaches 900 Wh/kg. Fourth, they offer high system energy density; the non-fluid nature of solid-state electrolytes allows for the formation of high-voltage cells through internal series connection, improving the assembly efficiency and energy density of power lithium battery systems. Fifth, they offer a wide range of positive and negative electrode materials, simultaneously utilizing new technologies such as metallic lithium anodes and high-potential cathode materials; all-solid-state metallic lithium-ion batteries represent the future direction of battery research and development. In addition, solid-state batteries have a wide operating temperature range and electrochemical stability window, and also have the potential for thin-film and flexible manufacturing.
2. Global companies are investing heavily in solid-state batteries to seize the initiative.
Due to the current limitations of lithium iron phosphate and ternary lithium-ion batteries, as well as the potential advantages of solid-state batteries, many companies in the power lithium battery, automotive and energy industry chains in Europe, the United States, Japan, South Korea and my country are actively developing and deploying solid-state batteries.
Overall, in Europe and the United States, the focus is primarily on startups developing solid-state battery technology, while in Japan, battery technology innovation is mainly driven by traditional automakers and machinery companies. Chinese companies entered the solid-state lithium-ion battery field relatively late, and their industrialization process has been slower, largely supported by research institutions and universities.
In terms of research and development, the main domestic players are research institutions under the Chinese Academy of Sciences (CAS), which have accumulated considerable experience and are basically at the same level as foreign counterparts. However, there is still significant room for improvement in energy density compared to theoretical values, and ionic conductivity and cycle life also urgently need further enhancement. Solid-state lithium-ion batteries are divided into three technical routes based on solid electrolytes: polymer, oxide, and sulfide solid electrolytes. Different research institutions adopt different technical routes. Among them, the Qingdao Institute of Energy and the Institute of Chemistry of CAS focus on polymer solid-state lithium-ion batteries. The former's experimental samples have an energy density of 300Wh/kg and have completed the first deep-sea test, while the latter has broken through the bottleneck of low conductivity of polymer solid electrolytes at room temperature. The Institute of Physics of CAS is characterized by its mastery of in-situ formation technology, and its 10Ah soft-pack battery has an energy density of 310-390Wh/kg and a volumetric energy density of 800-890Wh/L. The Ningbo Institute of Materials Technology and Engineering and the Shanghai Institute of Ceramics of CAS focus on the research of inorganic solid-state lithium-ion batteries and composite solid-state lithium-ion batteries, respectively.
3. Technological and industrial barriers urgently need to be overcome.
Through the joint efforts of the company and research institutions, solid-state battery technology has made breakthroughs, with energy density exceeding 300Wh/kg. However, these are mostly laboratory products and are still some distance from industrialization.
At the technical level, the ionic conductivity of solid-state electrolytes and the compatibility and stability of the solid/solid interface remain two major limiting issues. Polymer electrolytes have low conductivity at room temperature and generally require heating to above 60°C to function properly; for example, Bolloré & eAcute in France uses a polymer electrolyte and battery heating technology. The conductivity of sulfide electrolytes is currently comparable to that of traditional lithium-ion batteries, but the interfacial compatibility issue still needs to be addressed, primarily through material synthesis and nanolayer technology to increase the amount of active material and reduce interfacial layer resistance. Meanwhile, lithium metal anodes and novel composite cathode materials are still under development, potentially enabling the application of all-solid-state lithium metal batteries, at which point significant breakthroughs will be achieved in energy density, capacity, rate performance, safety performance, and cycle life.
At the industrialization level, the main obstacle to achieving large-scale production lies in production equipment, processes, and the production line environment. For example, the stacking, coating, and packaging processes in solid-state battery manufacturing require customized high-precision equipment, and the production line environment must maintain a higher level of dryness. Only when large-scale production achieves increased output and yield can the cost of solid-state lithium-ion batteries be reduced.
Overall, the maturity of solid-state lithium-ion battery production still needs significant improvement, and large-scale, automated production lines require further development. Currently, the industry is still in a period of accumulation. The general development path for solid-state batteries is as follows: due to the stability issues at the solid/solid interface, the content of liquid electrolytes will gradually decrease, transitioning from liquid-to-semi-solid, solid-liquid hybrid, and all-solid-state batteries. In the development of all-solid-state lithium metal batteries, due to the rechargeability issues of lithium metal anodes, the anode material will transition from graphite alloyed anodes (such as Si/C) to lithium metal anodes. With advancements in R&D technology and industrial production, the performance and production of solid-state batteries will gradually improve, bringing opportunities to the power lithium battery market.
III. Potential alternatives to these technologies still exist.
In addition to improvements to current lithium-ion batteries and the development of solid-state batteries, domestic and foreign companies, institutions, and universities have made various attempts in the innovation of power lithium battery technology. Some indicators have been significantly improved compared to the current level, providing a strong reference for improving the performance of power lithium batteries.
By analyzing the technical indicators of collected typical innovative cases, it can be found that some key indicators of products have been improved. In terms of energy density, aluminum-air batteries reach 780Wh/kg, lithium-sulfur batteries reach 350Wh/kg, and solid-state batteries reach 360Wh/kg. Regarding charging rate, the highest charging rate of typical innovative products has exceeded 100C. In terms of cycle life, typical innovative products have achieved over 15,000 cycles.
New types of 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 promising high specific capacity battery technology, which utilizes the reversible reaction of lithium metal and oxygen, and the theoretical energy density can reach up to 11000Wh/kg. Second, in terms of industry, they can reduce dependence on scarce resources. For example, sodium-ion batteries have the advantage of abundant reserves and lower cost compared to lithium-ion batteries.
However, most innovative lithium-ion battery products currently available for power use are still in the laboratory stage. These new batteries face numerous challenges in their industrialization process. For example, lithium-sulfur batteries suffer from low safety, low volumetric energy density, low discharge rate, low energy conversion efficiency, and low cycle life, making them difficult to apply in the automotive field in the short term. In general, while these studies are currently in the experimental stage and far from industrialization, their ability to replace existing battery systems in the short term remains controversial within the industry. However, there is no doubt that these batteries have the potential to break through some of the current technological bottlenecks in power lithium-ion batteries, reduce battery costs, and create longer driving ranges. These batteries cannot be ignored in the development of the power lithium-ion battery industry.
IV. Summary
From a technological development perspective, ternary lithium and lithium iron phosphate batteries currently dominate the automotive power lithium battery market, and these two technologies have become the main technological routes for mainstream companies. The company is further developing these two technologies. While breakthroughs have been achieved in ternary lithium and lithium iron phosphate battery technologies, there is still room for further technological improvement, and competition in the industry will continue for some time.
From the perspective of new battery technology development, solid-state batteries have technological advantages and can solve many problems currently facing the industry, leading to a rush of domestic and foreign companies to invest in and achieve technological breakthroughs. However, from the perspective of industry development, solid-state batteries are currently in a period of industry accumulation, and many issues related to technology and industrial support still need to be resolved.
On the other hand, besides improvements to current lithium-ion batteries and the development of solid-state batteries, many research institutions are also developing next-generation batteries such as lithium-sulfur and lithium-air batteries, and have made breakthroughs in some technologies, providing valuable references for the development of the battery industry. However, in general, these studies are basically in the experimental stage and far from industrialization, and there is also much controversy in the industry. But it is undeniable that these batteries have the potential to break through some bottlenecks of current power lithium batteries and cannot be ignored in the development of the industry.
While improving the performance of existing technology products, battery companies should also actively invest in the research and development of next-generation batteries to gain a dominant position in the next round of competition. Government departments should encourage companies, research institutions, and universities to conduct research and development on key materials, battery cells, and system technologies for power lithium batteries through various channels such as science and technology programs (special projects, funds), relevant innovation projects, and high-tech industry development projects. They should also actively promote the engineering and industrialization of key technologies and equipment for the preparation, production processes, and testing of new products and materials such as solid-state batteries, lithium-sulfur batteries, and metal-air batteries, advance the construction of engineering and technical capabilities across the entire industry chain, and promote the application of new power lithium battery technologies and products in demonstration and promotion projects.
