Solid-state lithium-ion battery -Lithium - Ion Battery Equipment

Solid-state lithium-ion battery -Lithium - Ion Battery Equipment

All-solid-state lithium-ion batteries use solid-state electrolytes to replace traditional organic liquid electrolytes, which are expected to fundamentally solve the problem of battery safety. They are ideal chemical power sources for electric vehicles and large-scale energy storage. In order to achieve large capacity and long life, and thus promote the practical application of all-solid-state lithium-ion batteries, the development and performance optimization of key battery materials are urgent, including the preparation of solid-state electrolytes with high room temperature conductivity and electrochemical stability, as well as solid-state electrolytes suitable for all-solid-state lithium-ion batteries. High-energy electrode materials for solid-state lithium-ion batteries, improving electrode/solid electrolyte interface compatibility.

Introduction to Solid State Batteries

Traditional lithium-ion batteries use organic liquid electrolytes. Under abnormal conditions such as overcharging and internal short-circuits, the batteries are prone to heat, causing the electrolyte to swell, spontaneously combust, or even explode, posing serious safety hazards. The all-solid-state lithium battery based on solid electrolyte developed in the 1950s, because of the use of solid electrolyte, does not contain flammable and volatile components, and completely eliminates the safety hazards such as battery smoke and fire caused by battery leakage. For the safest battery system. For energy density, the governments of China, the United States, and Japan hope to develop prototype devices of 400-500Wh/kg in 2020, and achieve mass production in 2025-2030. To achieve this goal, the most likely metal is currently recognized In the use of lithium anode, metal lithium has many technical challenges in traditional liquid lithium-ion batteries, such as dendrites, pulverization, SEI (solid electrolyte interface film) instability, and many surface side reactions, and the compatibility of solid electrolyte and metal lithium makes It is possible to use lithium as the negative electrode, thereby achieving a significant increase in energy density.(Lithium - Ion Battery Equipment)

Comparison of properties of different types of electrolytes and their lithium-ion battery systems

Research Progress of Solid Electrolytes

For solid-state batteries, the solid-state electrolyte is the core component that distinguishes it from other battery systems. The ideal solid-state electrolyte should have high lithium ion conductivity in the operating temperature range (especially normal temperature); the grain boundary impedance can be ignored or absent; and The thermal expansion coefficient of the electrode material is matched; during the charging and discharging process of the battery, it maintains good chemical stability for the positive and negative electrode materials, especially the metal lithium or lithium alloy negative electrode; the electrochemical wide opening is wide, the decomposition voltage is high; it is not easy to absorb moisture, and the price Low cost, simple preparation process and environmental friendliness.

Currently, the material system for polymer electrolytes in mass-produced polymer solid-state batteries is polyethylene oxide (PEO). PEO-based polymer electrolytes are characterized by high ionic conductivity at high temperature, easy film formation, and easy processing. After compounding with the positive electrode, a continuous ionic conduction channel can be formed, and the positive electrode surface resistance is small. The oxidation potential of PEO is 3.8V, which is difficult to match with high energy density cathodes such as lithium cobalt oxide, layered oxide, and spinel oxide, and needs to be modified; secondly, the working temperature of PEO-based electrolyte is 60-85 °C , The battery system requires thermal management, which requires special battery system design for power and energy storage applications; again, this type of battery directly uses metal lithium, and there are still lithium dendrites at the interface during the charge and discharge process. The potential of internal short circuit is caused by passing through the polymer film, and the rate characteristic also needs to be improved. The development of polymer electrolytes with high voltage resistance, high room temperature ionic conductivity, blocking lithium dendrite mechanism, and good mechanical properties is a key research direction.

Inorganic solid-state electrolytes mainly include oxides and sulfides. The solid-state batteries that have been produced in small batches are mainly thin-film batteries with amorphous LiPON as the electrolyte. The advantages of inorganic solid electrolytes are that some materials have high bulk ionic conductivity, can withstand high voltages, have good electrochemical, chemical, and thermal stability, and have certain effects in inhibiting lithium dendrites.




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