The endless incidents of electric vehicles burning cars and everyone's concerns about the battery of the energy storage system point directly to the two most important application scenarios to be solved, that is, electric vehicles and energy storage systems. And this is also the application scenario where solid-state batteries have the most chance to win.
What is Solid State Battery?
Solid-state battery is a kind of battery using solid electrodes and solid electrolyte, and it is also a member of the lithium battery family. Compared with traditional lithium batteries, the electrolyte is liquid, while the electrolyte used in solid-state batteries is solid, and solves two major shortcomings of liquid batteries: safety issues and energy density.
Characteristics of Solid-State Batteries
- High safety: The solid-state battery uses a solid-state electrolyte, which has no problems such as leakage pollution, flammable explosion, etc., and the electrolyte is a solid state. The battery will not cause short-circuit explosion due to the damage of the separator. The strong blocking effect of positive and negative electrodes is less likely to generate lithium dendrites and cause short circuits, and the safety is higher.
- High energy density: Due to the safety of solid-state batteries, materials with higher energy density can be selected for the positive and negative electrodes, such as lithium metal for the negative electrode or NCMA mixture for the positive electrode, etc., so that the energy density has the opportunity to exceed that of lithium ternary batteries. Compared with the liquid lithium-ion battery of the same volume, the solid electrolyte energy density can have higher battery storage energy, and the charging and discharging speed is also fast.
- Small size: Solid-state batteries are lighter, easier to package, greatly increase the volumetric energy density, and do not require monitoring, cooling and thermal insulation systems for lithium-ion batteries. The vehicle chassis can free up more space for batteries, which also helps Increase the battery life of electric vehicles.
In summary, the main advantages of solid-state batteries are: high safety and energy density, fast charging speed, long life, good thermal stability, and will not freeze at low temperatures (heat and cold resistance), etc. In addition, the use of raw materials can be greatly reduced, among which copper and the use of aluminum will drop by a large percentage, and graphite and cobalt can be eliminated from the raw materials. However, solid-state batteries still have problems to be overcome. They are costly and difficult to mass-produce. The internal structure of solid-state batteries is compact and easily affected by thermal expansion and contraction. If the design is improper, the internal structure may be affected.
Types of Solid-State Batteries
According to the different solid electrolyte materials, it is divided into three major technologies: polymer, sulfide and oxide. Among them, polymers belong to organic polymer electrolytes, and sulfides and oxides belong to inorganic ceramic electrolytes.
- Polymer: The polymer electrolyte is mainly composed of a polymer matrix and a lithium salt. The advantages are that it is easy to process, and the manufacturing process is similar to that of traditional lithium batteries. It is the easiest solid-state battery to use existing equipment to achieve mass production through transformation. The first to realize industrialization. However, its ionic conductivity is the lowest, and it must be heated to more than 60 degrees to increase the ionic conductivity. Polymers are organic substances with poor electrochemical performance, resulting in the inability to improve energy density.
- Sulfide: Sulfide electrolyte has the highest ionic conductivity, but has poor air stability. It is easy to produce toxic hydrogen sulfide when exposed to air. The special needs of production equipment and production environment will cause high costs.
- Oxide: Oxide electrolyte has the highest safety among the three major technologies, but it is also the most difficult to develop. However, the mechanical properties of the oxide are hard, and if it is used to make an electrolyte sheet, it is easier to break; the contact with the positive electrode active material is not good enough, resulting in the change from surface contact to point contact, and the interface loss is too large.
The Two Potential Application Scenarios for Solid-State Batteries
The endless incidents of electric vehicles burning cars and everyone's concerns about the battery of the energy storage system point directly to the two most important application scenarios to be solved, that is, electric vehicles and energy storage systems.
Application Scenario 1: Electric Vehicles
For electric vehicles, the most important and expensive part is the battery, which accounts for 40% to 60% of the total cost. It can be said that whoever masters the battery technology will master the next generation of electric vehicle technology. Therefore, everyone wants to find an alternative to liquid lithium batteries. Under this opportunity, the new star of solid-state batteries was born, so electric vehicles have become a potential application scenario of solid-state batteries. Such a good opportunity, why does it fall on solid-state batteries? There are three main reasons:
- Non-flammable, non-corrosive, non-volatile, non-leakage, high-temperature-resistant solid electrolyte replaces electrolyte, electrolyte salt and diaphragm, and completely solves the problem of burning cars caused by spontaneous combustion of batteries.
- The energy density has a great chance to exceed 500Wh/kg, which can increase the battery life of electric vehicles to 800 kilometers to 1,000 kilometers, which is higher than that of lithium ternary batteries.
- The solid-state battery can greatly reduce the weight of the electric vehicle drive system. Since the solid-state battery cell does not contain liquid, the risk of spontaneous combustion can be greatly reduced. Therefore, it can be connected in series and then packaged to reduce the redundancy caused by the external series connection of the existing liquid lithium battery. Mechanism design; at the same time, due to its completely non-flammable characteristics, the BMS temperature control components will be greatly reduced, thereby improving the endurance.
Application Scenario 2: Energy Storage System
Compared with electric vehicles, there are many different battery options for energy storage systems, but the advantages of lithium battery energy storage systems for rapid response are still necessary for participating in the power system, and occupy a certain importance in the development of the energy storage market.
Although it is still too early for solid-state batteries to be applied to energy storage systems at this stage, the energy storage market has already begun to pay attention to the development of solid-state battery technology. Why do solid-state batteries have a chance? There are three main reasons:
- Non-flammable, non-corrosive, non-volatile, non-leakage, high-temperature-resistant solid electrolyte replaces electrolyte, electrolyte salt and diaphragm to solve the problem of fire caused by batteries in energy storage systems.
- Most energy storage systems do not require fast charging like electric vehicles, and solid-state batteries are handier here.
- If it can be mass-produced, because the solid-state battery cells do not contain liquid, the risk of spontaneous combustion can be greatly reduced, so they can be connected in series and then packaged to reduce the redundant mechanism design caused by the external series connection of the existing liquid lithium batteries; With its completely non-flammable characteristics, BMS temperature control components can be greatly reduced, thereby reducing the cost of shell design. Under these two factors, it can simplify the production process and improve the cost competitiveness.
Solid-state batteries have not yet been mass-produced, and lithium batteries will still dominate the energy storage system for a period of time. After all, lithium iron phosphate batteries are low-cost, relatively safe, and have a battery cycle life of more than 3,000 times, which can be used for eight to ten years. It can meet the needs of the existing energy storage market. The business opportunities of these two application scenarios are so large enough for investors to join the market as soon as possible!