Study on coating and drying of lithium iron phosphate positive electrode sheets

The coating and drying of lithium battery pole pieces accounts for 8% to 10% of the entire manufacturing cost of lithium batteries, which is mainly due to the low thermal efficiency of the pole piece drying process. In addition, the residual solvent in the pole piece drying process has a great impact on the stability, capacity and cycle life of the subsequent processing of the pole piece. The pole piece drying process not only affects the manufacturing cost of the battery, but also indirectly determines the manufacturing process level and safety.This paper studies the drying characteristics of the coating layer of the positive electrode of LiFePO4 battery under static drying and hot air tunnel drying conditions, and analyzes its drying rules to provide a reference for optimizing the hot air drying process and the development of corresponding drying equipment.

Lithium battery positive and negative plates

1. What is the coating substrate?

In lithium-ion batteries, the positive and negative active materials are coated on the substrate to make the pole pieces, which are then wound or stacked to form the battery cell. The substrates used here are mainly copper foil and aluminum foil. The current lithium battery positive electrode is aluminum foil and the negative electrode is copper foil. This is because copper is easily oxidized at the positive electrode with a higher potential. At the same time, there is a dense oxide layer on the surface of the aluminum foil, which protects the internal aluminum at high potential.

Understanding how lithium battery electrodes are prepared and how the quality of the electrodes during the preparation process affects the battery's performance.

1. Lithium battery pole piece production process

The general process of lithium-ion battery pole piece manufacturing is : pulping, coating, drying, rolling, cutting, etc. The specific process flow is shown in the figure below.

Lithium battery pole piece design basics, common defects and their impact on battery performance

1.Basics of Pole Design

The lithium battery electrode is a coating composed of particles, which is evenly coated on the metal current collector. The lithium-ion battery electrode coating can be regarded as a composite material, which mainly consists of three parts:

Detailed explanation of the coating process of lithium-ion battery pole pieces

Effect of coating process on lithium battery performance

Pole sheet coating generally refers to a process of evenly coating the stirred slurry on the current collector and drying the organic solvent in the slurry. The coating effect has an important impact on the battery capacity, internal resistance, cycle life and safety, ensuring that the pole sheet is evenly coated. The selection of coating method and control parameters have an important impact on the performance of lithium-ion batteries, mainly manifested in:

Some possible reasons and corresponding explanations for the preparation and process of button cells/soft packs

Button battery

1.Basic Introduction

Lithium-ion button batteries are mainly composed of the following parts: positive electrode shell, negative electrode shell, (positive/negative) electrode sheet, diaphragm, gasket, spring, and electrolyte. The C in the commonly used regular commercial button battery CR2032 indicates that the positive electrode is MnO2, and there is also a BR series, and B indicates that the positive electrode is carbon fluoride. C or B represents the button battery system, and R represents that the battery shape is round.

Assembly of button batteries

1.About

Button cells, also known as coin cells or battery cells, are compactly designed batteries shaped like small buttons. They are widely used in various small electronic devices, such as car keys, TWS wireless earbuds, watches, calculators, hearing aids, and some medical devices and precision electronic instruments. Their characteristics include a small size and light weight, making them ideal for applications where space is limited.