All-solid-state lithium-ion batteries use solid electrolytes to replace traditional organic liquid electrolytes, which are expected to fundamentally solve battery safety issues and are ideal chemical power sources for electric vehicles and large-scale energy storage. The types of all-solid-state batteries can be divided into three categories: thin-film all-solid-state batteries, 3D thin-film all-solid-state batteries, and bulk all-solid-state batteries. The various components of the battery are made into thin films by appropriate thin film preparation technology (such as vapor deposition, ion sputtering, sol-gel, laser pulse deposition, etc.), and stacked on the substrate in the order of the battery structure to form a thin film all-solid-state battery. Thin-film all-solid-state batteries have high volume energy density and mass energy density, and can be widely used in portable mobile devices, electric mobility tools, medical equipment, aerospace and military industries. With the help of template method, photolithography technology, aerogel method, plasma etching and other technologies, the thin film battery can be made into a three-dimensional structure, which can further improve the power density and energy density per unit area of the battery. The electrode layer of the bulk all-solid-state battery carries more electrode active materials, and thus can provide greater output power and energy density per unit area. Due to the thick electrode layer, in order to make full use of the electrode active material, the design of the electrode adopts the concept of a liquid battery electrode, that is, a composite electrode is composed of a mixture of lithium ion conductive materials and electrode active materials, as shown in Figure 1.
Structure of all solid-state lithium-ion battery
The structure of an all-solid-state lithium-ion battery mainly includes an electrolyte, a positive electrode, and a negative electrode, all of which are composed of solid materials, as shown in Figure 2. The key is to prepare solid electrolytes with high temperature, room temperature conductivity and electrochemical stability, high-energy electrode materials suitable for all-solid-state lithium-ion batteries, and to improve the compatibility of the electrode/solid electrolyte interface. Compared with traditional electrolyte lithium ion batteries, the advantages are as follows.
(1) The potential safety hazards of electrolyte corrosion and leakage are eliminated, and the thermal stability is higher.
(2) No need to encapsulate liquid, support serial stacking arrangement and bipolar structure, improve production efficiency.
(3) Due to the solid-state characteristics of solid electrolytes, multiple electrodes can be stacked.
(4) The electrochemical stability window is wide (up to 5V or more), which can match high-voltage electrode materials.
(5) Solid electrolytes are generally single-ion conductors, with almost no side reactions and longer service life.
The development of all-solid-state batteries mainly relies on the development of solid-state electrolyte materials. After their emergence in the middle of the 20th century, they experienced a slow development period, and now ushered in a golden period of rapid development. At present, solid electrolyte materials with potential can be divided into three types: polymer solid electrolyte, oxide solid electrolyte and sulfide solid electrolyte.