On October 9, 2019, the Royal Swedish Academy of Sciences announced that the 2019 Nobel Prize in Chemistry was awarded to John B. Goodenough, M. Stanley Whittingham and Akira Yoshino for their contributions to the research and development of lithium-ion batteries. They created a rechargeable world. Lithium-ion batteries are used globally to power the portable electronics that we use to communicate, work, study, listen to music and search for knowledge.
However, scientists believe that lithium-ion batteries have reached their limit, and solid-state batteries have been regarded as batteries that are capable of inheriting the status of lithium-ion batteries in recent years. Due to the high power and weight of solid-state batteries, they are a better choice for electric vehicle batteries than lithium-ion batteries. So let me give you some detailed introductions about solid-state batteries.
What is a solid-state battery?
Solid-state battery is a battery technology that uses solid electrodes and a solid electrolyte, instead of the liquid or polymer gel electrolytes found in lithium-ion or lithium polymer batteries.
Although solid electrolytes was first discovered in the 19th century, several drawbacks have prevented its widespread application. Developments in the late 20th and early 21st century have caused renewed interest in solid-state battery technologies, especially in the context of electric vehicles, starting in the 2010s.
The main difference between solid-state batteries and lithium-ion batteries is electrolyte. Lithium-ion batteries use liquid electrolytes, which has problems with weight, safety and lifespan.
Due to the low energy of a single battery, multiple batteries must be connected in series, which further increases the weight. Facing risk of instability and flammability at high temperatures, the liquid electrolyte might potentially cause fires in car accidents. It is also prone to freezing at low temperatures, reducing cruising ability. In addition, the electrolyte might corrode the internal components of the battery, and the process of charging and discharging will also generate dendrites, reducing the capacity, performance and life of the battery.
However, solid-state batteries use solid electrolyte with high energy density. Although the battery structure and charging method is the same as traditional lithium batteries, there is little liquid inside the solid-state battery, the internal energy density is higher, and the volume is smaller. Solid-state batteries are lighter in weight. They require no monitoring, cooling and thermal insulation systems of lithium-ion batteries, so the chassis can free up more space for batteries, which greatly increases the cruising ability of electric vehicles.
According to the above description, the advantages of solid-state batteries can be briefly summarized:
--High safety. Many solid electrolyte materials are non-flammable, non-corrosive, non-volatile, and non-leakage. Compared with liquid electrolytes containing flammable solvents, polymer solid electrolytes have significantly improved battery safety.
--High energy density. By using metal lithium as the negative electrode, the energy density of solid-state lithium batteries will reach 300-400Wh/kg or even higher; By reducing the weight of the battery without liquid electrolytes and separators, compressing the internal space of the battery and increasing the energy density.
--Long cycle life. It avoids the problem of continuous formation and growth of solid electrolyte interphase and lithium dendrites piercing through the separator during the charge and discharge process of the liquid electrolyte, greatly improving the cyclability and service life of lithium metal batteries.
--Wide operating temperature range. In a nail penetration test, solid-state lithium batteries have high-temperature resistance and excellent stability. The use of inorganic solid electrolytes can avoid thermal runaway caused by the reaction of positive and negative electrode materials with the electrolyte at high temperatures, and the maximum operating temperature can reach 300°C.
--Flexibility. All-solid-state lithium batteries can be prepared into thin-film batteries and flexible batteries. Compared with flexible liquid electrolyte lithium batteries, the packaging is easier and safer, which can be applied to smart wearables and implantable medical devices in the future.