Solid-state battery mass production technology breakthrough -Lithium - Ion Battery Equipment
In 1991, Sony launched commercial lithium batteries for the first time. Since then, with the unremitting efforts of scientific researchers and engineers, the performance of lithium batteries has been greatly improved [1], and the application field of lithium batteries has also changed from the original 3C. The field of consumer electronics has expanded to new energy vehicles and distributed energy storage. The application of lithium batteries in the field of power lithium batteries has also prompted its pursuit of energy density to continue to rise. Although the current energy density of lithium batteries is more than three times that of the original Sony products [2], it is still unable to meet the increasing demand. cruising range requirements. Nowadays, the energy density improvement of traditional liquid electrolyte lithium batteries is close to its limit value, and it is difficult to meet the needs of the next generation of high specific energy power lithium batteries. Therefore, mainstream power lithium battery manufacturers are also deploying next-generation power lithium battery technology.(Lithium - Ion Battery Equipment)
Among the many candidates for next-generation power lithium batteries, solid-state batteries are the most promising one. All-solid-state batteries are not only relatively mature in technology, but also supported by a group of outstanding international scholars such as Goodenough and Cui Yi. Many domestic and foreign lithium battery companies have also regarded all-solid-state battery technology as an important next-generation technology reserve. The two most significant advantages of all-solid-state batteries are as follows:
1. High energy density
The current lithium battery uses graphite material as the negative electrode. The theoretical specific capacity of graphite is only 372mAh/g, which is far from meeting the needs of high specific energy lithium batteries. The theoretical specific capacity of metal Li negative electrode can reach 3860mAh/g. It is an ideal anode material for high specific energy batteries, but Li metal anode will form Li dendrites in the process of repeated charge and discharge [3], resulting in low Coulomb efficiency and increased short circuit risk, while solid electrolytes have the characteristics of high shear modulus , which can better inhibit the growth of Li dendrites [4], so we can use metal Li as the negative electrode in solid-state batteries. Related research shows that even at lower areal densities, using metal Li to replace traditional graphite can still be used. Increase the energy density of the battery by more than 35%. If we use NCM811 material as the positive electrode, the energy density of the battery can reach more than 500Wh/kg, and even if LFP is used as the positive electrode, the energy density of the battery can be increased to more than 300Wh/kg [5]. This is unmatched by traditional liquid electrolyte lithium batteries.
2. High security
Safety is another thorny issue currently faced by liquid electrolyte lithium batteries, and the emergence of solid electrolytes has greatly improved the safety of lithium batteries. The research shows that the Li/LFP battery with liquid electrolyte starts to have a self-exothermic reaction at about 90 °C, and causes the battery thermal runaway at about 178 °C, while the self-exothermic temperature of the Li/LFP battery with solid electrolyte increases to 247 °C. above, and no thermal runaway occurred in the whole process [6]. Traditional liquid electrolyte lithium batteries are often thermal runaway caused by large-area short circuits caused by thermal shrinkage and melting of the separator caused by high temperature. Taking inorganic solid electrolytes as an example, the thermal stability is significantly higher than that of polymer separator materials [ 7], so the risk of short circuit of positive and negative electrodes caused by high temperature is almost zero, which greatly reduces the risk of thermal runaway of lithium batteries using solid electrolytes. At the same time, even if the battery has thermal runaway, the flammable composition of the solid electrolyte is far lower than that of the traditional carbonate electrolyte, which can significantly reduce the severity of thermal runaway of the lithium battery. improvement.
Solid electrolytes can be divided into three major categories in terms of composition: 1) oxide electrolytes, such as common LLZO-based electrolytes; 2) sulfide electrolytes, such as Li2S–P2S5 electrolytes; 3) organic polymer electrolytes, such as common PEO-based electrolytes polymer electrolytes, etc.
Among the many candidates for next-generation power lithium batteries, solid-state batteries are the most promising one. All-solid-state batteries are not only relatively mature in technology, but also supported by a group of outstanding international scholars such as Goodenough and Cui Yi. Many domestic and foreign lithium battery companies have also regarded all-solid-state battery technology as an important next-generation technology reserve. The two most significant advantages of all-solid-state batteries are as follows:
1. High energy density
The current lithium battery uses graphite material as the negative electrode. The theoretical specific capacity of graphite is only 372mAh/g, which is far from meeting the needs of high specific energy lithium batteries. The theoretical specific capacity of metal Li negative electrode can reach 3860mAh/g. It is an ideal anode material for high specific energy batteries, but Li metal anode will form Li dendrites in the process of repeated charge and discharge [3], resulting in low Coulomb efficiency and increased short circuit risk, while solid electrolytes have the characteristics of high shear modulus , which can better inhibit the growth of Li dendrites [4], so we can use metal Li as the negative electrode in solid-state batteries. Related research shows that even at lower areal densities, using metal Li to replace traditional graphite can still be used. Increase the energy density of the battery by more than 35%. If we use NCM811 material as the positive electrode, the energy density of the battery can reach more than 500Wh/kg, and even if LFP is used as the positive electrode, the energy density of the battery can be increased to more than 300Wh/kg [5]. This is unmatched by traditional liquid electrolyte lithium batteries.
2. High security
Safety is another thorny issue currently faced by liquid electrolyte lithium batteries, and the emergence of solid electrolytes has greatly improved the safety of lithium batteries. The research shows that the Li/LFP battery with liquid electrolyte starts to have a self-exothermic reaction at about 90 °C, and causes the battery thermal runaway at about 178 °C, while the self-exothermic temperature of the Li/LFP battery with solid electrolyte increases to 247 °C. above, and no thermal runaway occurred in the whole process [6]. Traditional liquid electrolyte lithium batteries are often thermal runaway caused by large-area short circuits caused by thermal shrinkage and melting of the separator caused by high temperature. Taking inorganic solid electrolytes as an example, the thermal stability is significantly higher than that of polymer separator materials [ 7], so the risk of short circuit of positive and negative electrodes caused by high temperature is almost zero, which greatly reduces the risk of thermal runaway of lithium batteries using solid electrolytes. At the same time, even if the battery has thermal runaway, the flammable composition of the solid electrolyte is far lower than that of the traditional carbonate electrolyte, which can significantly reduce the severity of thermal runaway of the lithium battery. improvement.
Solid electrolytes can be divided into three major categories in terms of composition: 1) oxide electrolytes, such as common LLZO-based electrolytes; 2) sulfide electrolytes, such as Li2S–P2S5 electrolytes; 3) organic polymer electrolytes, such as common PEO-based electrolytes polymer electrolytes, etc.
