Application Development Of All Solid-state Thin Film Lithium Batteries

The development of chemical power sources has been moving in the direction of high specific energy, long life and high safety. All-solid-state thin-film lithium batteries have become the most popular type of lithium batteries. Inorganic all-solid-state thin-film lithium batteries use thin-film positive and negative electrodes and thin-film solid electrolytes. The thin film morphology of the solid electrolyte makes it possible to replace the liquid electrolyte with a solid electrolyte with lower ionic conductivity. The thin film morphology of the positive and negative electrodes makes it possible to apply many positive and negative materials with large changes in charge and discharge volume, such as metal lithium and thin film silicon Wait. At the same time, due to the thin film morphology of thin-film lithium batteries, it is easy to process into micron-sized batteries, and even further research into nano-sized batteries. Therefore, thin-film lithium batteries have not only become the research hotspot of next-generation chemical power sources, but also the inevitable research on micro-batteries. Direction of development.

The current research directions for inorganic all-solid-state thin-film lithium batteries are mainly divided into: (1) Research and develop new battery structures, improve the battery capacity per unit area and discharge power, and solve the problem of low unit area capacity and power of thin-film lithium batteries: (2) Research on new types of solid electrolytes with high ionic conductivity to solve the problem of low lithium ion conductivity in inorganic solid electrolytes: (3) Research on new types of positive and negative electrodes, so that the positive and negative electrodes after film formation have better

1. Research on the structure of thin film lithium batteries

The thin-film lithium battery adopts a classic laminated structure, which is simple in structure and easy to process. However, in order to further improve the performance of the battery, the research on the structure of the thin film lithium battery is gradually increasing, especially the 3D structure thin film lithium battery has become a research hotspot due to its good performance expectations. In the 3D structure of the thin film lithium battery, it is similar to the porous structure of the 3D battery. This kind of battery is processed with many regularly arranged micropores on the silicon substrate, and the Li diffusion barrier layer TiN is deposited in the micropores, and then the silicon is used as the negative electrode. LiPON is Electrolyte, LiCoO2 is the positive electrode to make the battery.

2. Research on inorganic solid electrolyte

Batteries using inorganic solid electrolytes have many advantages over electrolyte batteries, such as electrochemical stability, thermal stability, shock resistance, impact resistance, no leakage and pollution problems, and easy miniaturization and thin film formation. A good inorganic solid electrolyte should have the following characteristics: (1) High lithium ion conductivity and almost negligible electronic conductivity within the lithium active state and ambient temperature range; (2) It must be stable under electrochemical reactions, especially The interface in contact with the negative electrode of lithium or lithium alloy; (3) In order to use it, the solid electrolyte must be environmentally friendly, non-toxic, low-cost and easy to prepare, and it is best that the thermal expansion coefficient can be consistent with the electrodes on both sides, at least not too different .

(1) Crystalline inorganic electrolyte

At present, crystalline inorganic electrolytes have shown high ionic conductivity in many reports, and they can be divided into solid electrolytes of NASICON type, LISICON type, Thio-LISICON type, perovskite type and other structures. The structure of the NASICON solid electrolyte is generally M[A2B3O12]. Although the NASICON electrolyte has high ionic conductivity, the T product is easily reduced by the metal lithium, resulting in unstable contact with the metal lithium.

LISICON also has high ionic conductivity. Its typical structure is Lisa.Zn1.GeO1sThio-LISl-CON type electrolyte to improve the ionic conductivity of the electrolyte. In LISICON type electrolyte, sulfur is used instead of oxygen, such as Li2GeS3, Li4GeS4, Li2ZnGeS4 And other new materials, its ion conductivity can reach 6.5×10-5S/cm.

The current research directions for inorganic all-solid-state thin-film lithium batteries are mainly divided into: (1) Research and develop new battery structures, improve the battery capacity per unit area and discharge power, and solve the problem of low unit area capacity and power of thin-film lithium batteries: (2) Research on new types of solid electrolytes with high ionic conductivity to solve the problem of low lithium ion conductivity in inorganic solid electrolytes: (3) Research on new types of positive and negative electrodes, so that the positive and negative electrodes after film formation have better

1. Research on the structure of thin film lithium batteries

The thin-film lithium battery adopts a classic laminated structure, which is simple in structure and easy to process. However, in order to further improve the performance of the battery, the research on the structure of the thin film lithium battery is gradually increasing, especially the 3D structure thin film lithium battery has become a research hotspot due to its good performance expectations. In the 3D structure of the thin film lithium battery, it is similar to the porous structure of the 3D battery. This kind of battery is processed with many regularly arranged micropores on the silicon substrate, and the Li diffusion barrier layer TiN is deposited in the micropores, and then the silicon is used as the negative electrode. LiPON is Electrolyte, LiCoO2 is the positive electrode to make the battery.

2. Research on inorganic solid electrolyte

Batteries using inorganic solid electrolytes have many advantages over electrolyte batteries, such as electrochemical stability, thermal stability, shock resistance, impact resistance, no leakage and pollution problems, and easy miniaturization and thin film formation. A good inorganic solid electrolyte should have the following characteristics: (1) High lithium ion conductivity and almost negligible electronic conductivity within the lithium active state and ambient temperature range; (2) It must be stable under electrochemical reactions, especially The interface in contact with the negative electrode of lithium or lithium alloy; (3) In order to use it, the solid electrolyte must be environmentally friendly, non-toxic, low-cost and easy to prepare, and it is best that the thermal expansion coefficient can be consistent with the electrodes on both sides, at least not too different .

(1) Crystalline inorganic electrolyte

At present, crystalline inorganic electrolytes have shown high ionic conductivity in many reports, and they can be divided into solid electrolytes of NASICON type, LISICON type, Thio-LISICON type, perovskite type and other structures. The structure of the NASICON solid electrolyte is generally M[A2B3O12]. Although the NASICON electrolyte has high ionic conductivity, the T product is easily reduced by the metal lithium, resulting in unstable contact with the metal lithium.

LISICON also has high ionic conductivity. Its typical structure is Lisa.Zn1.GeO1sThio-LISl-CON type electrolyte to improve the ionic conductivity of the electrolyte. In LISICON type electrolyte, sulfur is used instead of oxygen, such as Li2GeS3, Li4GeS4, Li2ZnGeS4 And other new materials, its ion conductivity can reach 6.5×10-5S/cm.