I. Current ternary and lithium iron phosphate battery technologies are highly mature.
1. Ternary and lithium iron phosphate batteries are the key areas of focus for enterprises.
In the field of automotive power batteries, lithium batteries have become the mainstream. Currently, the main battery types used by major international power battery companies are lithium iron phosphate and ternary lithium batteries.
In the Chinese market, lithium iron phosphate and ternary lithium batteries remain the mainstream power 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 batteries still have a period of development ahead.
After a period of development, the technological 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 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 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. In 2018, the energy density of single cells is expected to reach 230~250Wh/kg.
Both types of batteries still have room for improvement, especially with the role of next-generation materials in enhancing 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 batteries is 300-350 Wh/kg. Both 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 batteries possess significant potential for energy density enhancement and are theoretically more feasible.
1. Potential technological advantages of solid-state lithium batteries
Solid-state lithium batteries, compared to traditional lithium batteries, are characterized by the 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 battery. Solid-state electrolytes have changed the traditional structure of lithium batteries, making separators and liquid electrolytes unnecessary components, bringing significant technological advantages and potential.
The main technological advantages of solid-state lithium 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 formation of a solid electrolyte interface film that occurs with liquid electrolytes during charge-discharge cycles; the expected cycle life is currently 15,000-20,000 cycles. Third, they offer high energy density; in traditional lithium 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 the volumetric energy density. The estimated maximum potential energy density of all-solid-state lithium batteries reaches 900Wh/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 series connection, improving the assembly efficiency and energy density of power battery systems. Fifth, they offer a wide range of positive and negative electrode materials, simultaneously utilizing new technologies such as lithium metal anodes and high-potential cathode materials; all-solid-state lithium metal batteries represent the future direction of battery research and development. In addition, solid-state batteries have a wide operating temperature range, a wide electrochemical stability window, and the potential for thin-film and flexible manufacturing.
2. Global companies are investing heavily in solid-state batteries to gain a competitive edge.
Due to the current limitations of lithium iron phosphate and ternary lithium batteries, as well as the potential advantages of solid-state batteries, many companies in the power battery, automotive and energy industry chains in Europe, the United States, Japan, South Korea and China are actively developing and deploying solid-state batteries.
Overall, the focus in Europe and the United States 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 battery field relatively late, and their industrialization process has been slower, primarily 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 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 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 batteries and composite solid-state lithium batteries, respectively.
3. Technological and industrial barriers urgently need to be overcome.
Thanks to the efforts of enterprises and research institutions, solid-state battery technology has made breakthroughs, with energy densities 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 in France uses a polymer electrolyte and battery heating technology. The conductivity of sulfide electrolytes is currently comparable to that of traditional lithium batteries, but the interfacial compatibility issue still needs to be addressed, mainly 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, which are expected to enable the application of all-solid-state lithium metal batteries, at which time significant breakthroughs will be achieved in energy density, capacity, rate performance, safety performance, and cycle life.
At the industrialization level, the main obstacles to achieving large-scale production lie in production equipment, processes, and 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 also needs to maintain a higher level of dryness. Only when large-scale production increases output and capacity can the cost of solid-state lithium batteries be reduced.
Overall, the maturity of solid-state lithium battery production still needs improvement, and large-scale, automated production lines require further research and 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 electrolyte will gradually decrease, transitioning from liquid to semi-solid to solid-liquid hybrid to solid-state to 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 to 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 battery market.
III. Potential alternatives to these technologies still exist.
In addition to improvements to current lithium batteries and the development of solid-state batteries, domestic and foreign companies, institutions, and universities have made various attempts in power battery technology innovation. Some indicators have been significantly improved compared to the current level, providing a strong reference for improving the performance of power 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 power battery products currently available 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 batteries, reduce battery costs, and create longer driving ranges. These batteries cannot be ignored in the development of the power battery industry.
IV. Summary
From a technological development perspective, ternary lithium and lithium iron phosphate batteries currently dominate the automotive power battery market, becoming the main technological routes for mainstream companies, which are further developing these two technologies. While breakthroughs have been achieved in ternary lithium and lithium iron phosphate battery technology, there is still room for further 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, in addition to improvements to current lithium 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 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 enterprises, research institutions, and universities to conduct research and development on key materials, battery cells, and system technologies for power 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 battery technologies and products in demonstration and promotion projects.
