Hello everyone, today we're going to talk about solid-state batteries. A solid-state battery is a lithium-ion battery that uses a solid electrode and a solid electrolyte, which has the advantages of higher energy density, longer life, and better safety compared to traditional liquid electrolyte lithium batteries. Solid-state batteries are considered to be an important technical direction for the next generation of power batteries, and are expected to play an important role in new energy vehicles, energy storage, consumer electronics and other fields. However, solid-state batteries are also facing many challenges in technology and industrialization, which require us to continue to innovate and make breakthroughs. That's what I've brought to you about the basics of solid-state batteries.

Principle and classification of solid-state batteries

The principle of solid-state batteries is similar to that of liquid electrolyte lithium batteries, which uses the reciprocating movement of lithium ions between the positive and negative electrodes to achieve the charging and discharging process. The difference is that solid-state batteries use solid-state electrolytes instead of liquid electrolytes, which avoids potential safety hazards such as volatilization, leakage, and combustion of liquid electrolytes, and also improves the energy density of batteries, because the thickness of solid-state electrolytes can be thinner than the separator of liquid electrolytes, thereby reducing the internal resistance and weight of the battery. In addition, solid-state batteries can also use higher capacity anode materials, such as silicon, tin, lithium metal, etc., as well as higher voltage cathode materials, such as sulfur, oxides, etc., to further improve the energy density of the battery.

Depending on the solid-state electrolyte, solid-state batteries can be classified into the following types:

• Polymer solid-state batteries: Polymer materials are used as solid-state electrolytes, such as polyethylene oxide (PEO), polymer gels, etc. The advantage of polymer solid-state batteries is that the preparation process is simple, compatible with the equipment and process of liquid electrolyte lithium batteries, and the manufacturing of flexible batteries can be realized. The disadvantage is that polymer electrolytes have low lithium-ion conductivity, need to operate at higher temperatures, and are difficult to be compatible with high-voltage cathode materials.

• Inorganic solid-state batteries: use inorganic materials as solid-state electrolytes, such as oxides, sulfides, nitrides, phosphates, etc. The advantages of inorganic solid-state batteries are that the inorganic electrolyte has a high lithium-ion conductivity, can operate at room or low temperatures, and is compatible with high-voltage cathode materials. The disadvantage is that the preparation process of inorganic electrolyte is complex, which is incompatible with the equipment and process of liquid electrolyte lithium battery, which is difficult to achieve large-scale mass production, and there is the problem of poor solid-solid interface contact.
• Composite solid-state batteries: use composite materials as solid-state electrolytes, such as inorganic-organic composites, inorganic-inorganic recombinations, organic-organic composites, etc. The advantage of composite solid-state batteries is that the composite electrolyte can comprehensively use the advantages of different materials to improve the conductivity of lithium-ions, reduce internal resistance, and improve interfacial contact. The disadvantage is that the preparation process of composite electrolytes is difficult to control, and the compatibility and stability of composite materials need to be further studied.

Development status and challenges of solid-state batteries

As an emerging battery technology, solid-state batteries have received global attention and investment in recent years. At present, many well-known automobile manufacturers, battery manufacturers, scientific research institutions and start-up companies in the world are actively developing and promoting solid-state batteries, such as Toyota, Volkswagen, CATL, QuantumScape, Solid Power, etc. It is predicted that the market size of solid-state batteries will reach $1 billion in 2025 and exceed $10 billion by 2030.

However, the technology and industrialization of solid-state batteries still face many challenges, mainly including the following aspects:

• Solid-state electrolyte selection and optimization: Solid-state electrolyte is the core of solid-state batteries, which needs to have high lithium-ion conductivity, low electronic conductivity, high chemical stability, high mechanical strength, good thermal stability, and low cost. At present, there is no solid-state electrolyte that can meet these requirements at the same time, and it is necessary to select and optimize suitable solid-state electrolyte materials according to different application scenarios and technical routes.

• Improvement and control of solid-solid interface: In solid-state batteries, the interface contact between the solid-state electrolyte and the solid-state electrode is the key factor affecting the battery performance, and it is necessary to ensure good interface contact, low impedance, and high stability. At present, there are problems such as poor contact, excessive polarization, and excessive interface reaction at the solid-solid interface, and it is necessary to improve and control the performance of the solid-solid interface by optimizing the electrode structure, introducing the interface layer, and applying pressure.
• Matching and coordination of cathode and anode materials: In solid-state batteries, the selection and matching of cathode and anode materials are important factors affecting the energy density of the battery, and the capacity, voltage, expansion, stability and other characteristics of the cathode and anode materials, as well as the compatibility and interface reaction with the solid-state electrolyte need to be considered. At present, there are limited cathode and anode materials commonly used in solid-state batteries, such as high-nickel ternary cathode, silicon-carbon anode, lithium metal anode, etc., and it is necessary to further develop and optimize higher-performance cathode and anode materials, as well as achieve the coordination and balance of cathode and anode materials.

• Innovation and standardization of production process: The production process of solid-state batteries is very different from the production process of liquid electrolyte lithium batteries, and it is necessary to innovate and standardize the preparation methods, equipment, parameters, and standards of solid-state batteries. At present, the production process of solid-state batteries is not mature, and there are problems such as complex process, high cost, low efficiency, and unstable quality, and it is necessary to improve the production level and scale of solid-state batteries by introducing digital, intelligent, and automated technologies.

The above is the development status and challenges of solid-state batteries that I have introduced to you, welcome to follow my self-media blog, and I will share more interesting content for you from time to time. I am a ten-year car repair master, Lao Zhang, we will see you next time#固态电池! #