Button-type full battery design, assembly and testing tutorial and case analysis

1. Introduction

A full cell is a complete battery system that includes a positive electrode, a negative electrode, a separator, an electrolyte, and a shell. Unlike a half-cell, a full cell can provide an accurate assessment of the electrochemical and mechanical properties of an actual battery when it is in operation. A half-cell usually uses a metal sheet or foil (such as a lithium sheet or foil) as a counter electrode, while a full cell consists of two active electrodes, one as the positive electrode and the other as the negative electrode. The design and assembly of a full cell need to consider a variety of factors, including the choice of electrode materials, the type of electrolyte, the properties of the separator, and the structure of the battery shell to ensure the performance, safety, and reliability of the battery . Full cell testing is usually used to evaluate the degree of match between the positive and negative electrode materials and the rest of the battery, as well as the performance of the battery under actual use conditions. This article mainly introduces the design, assembly, and testing of full cells based on laboratory button-type full cells, and analyzes the factors affecting the design of full cells with examples.

The three-step process of button cell lithium battery assembly, testing, and data analysis.

 1.The Charging and Discharging Modes of Button Cells

The charging and discharging tests of button lithium batteries typically use constant current charging (CC), constant current-constant voltage charging (CC-CV), constant voltage charging (CV), and constant current discharging (DC) to test and analyze the battery's charging and discharging behavior. By analyzing the data changes during this process, various electrochemical performance parameters of the battery or material, such as capacity, coulombic efficiency, charging and discharging plateau, and internal parameter variations, can be characterized.

The preparation of lithium-ion battery electrode slurries and the assembly of coin (or button) cells

 1. Basic Introduction to Coin-Cell Batteries

Lithium-ion coin-cell batteries are mainly composed of the following parts: positive shell, negative shell, (positive/negative) electrode sheets, separator, gasket, spring, and electrolyte.

Commonly used coin-cell batteries include CR2032, CR2025, CR2016, etc. "C" represents a coin cell type, and "R" indicates the battery shape is round. The first two digits represent the diameter (in mm), and the last two digits represent the thickness (in 0.1 mm), with approximate numbers used for both. For example, the approximate dimensions of a CR2032 are 20 mm in diameter and 3.2 mm in thickness. 

The commercialization of all-solid-state battery production

The commercialization of all-solid-state battery production is a complex system engineering process, with its core mainly consisting of three key components: material system development, cell structure design, and cell production control. To produce a high-performance commercial all-solid-state battery, it is essential to master these three core aspects. Once the process for manufacturing commercial all-solid-state batteries is mastered, assembling and producing coin-type half-cells, coin-type full-cells, and simple structure flexible batteries (with a single positive/negative electrode stacked structure) becomes relatively easy.

Comparative Study of Titanium 32×MXene Coated Carbon Electrodes and Thermally Treated Carbon Electrodes for Vanadium Redox Flow Batteries in RSC Advances

1.Research Background

A major challenge in vanadium redox flow batteries is the competition between the main and side reactions of hydrogen evolution associated with the V(II)/V(III) redox couple at the negative electrode.

Lithium Battery Negative Electrode Lithium Deposition Causes and Solutions

1.What is Lithium Deposition on the Negative Electrode?

The lithium intercalation potential of graphite is between 65–200 mV (vs. Li+/Li0). When the potential of the negative electrode approaches or drops below the deposition potential of metallic lithium, lithium ions will be deposited as metallic lithium on the surface of the negative electrode. Experiments have shown that during the charging process, some lithium ions are deposited as metallic lithium on the surface of the negative electrode, while the remaining lithium ions intercalate into the graphite or other negative electrode materials. During discharge, both ion de-intercalation and the stripping of deposited lithium metal occur simultaneously. In the process of lithium metal stripping, "dead lithium" is formed.

In short, the phenomenon of lithium deposition on the negative electrode refers to the simultaneous intercalation and deposition of lithium ions during the charge and discharge processes, causing lithium to deposit as metallic lithium on the surface of the negative electrode, and resulting in the formation of "dead lithium" that cannot be reused.

Design of Electrolyte for Achieving 4.8V-Class NCM811-Lithium Metal Batteries in Angew

1.Research Abstract

Combining high-voltage nickel-rich cathodes with lithium metal anodes is one of the most promising approaches to achieving high-energy-density lithium batteries. However, most current electrolytes cannot simultaneously meet the requirements for compatibility with lithium metal anodes and tolerance for ultra-high-voltage NCM811 cathodes. In this study, by adjusting the composition of fluorinated carbonate-based electrolytes, an ultra-anti-oxidative electrolyte was designed. The research found that through the synergistic decomposition of fluorinated solvents and PF6- anions, an SEI (solid electrolyte interphase) rich in LiF and Li2O was constructed on the lithium anode, which facilitated smooth deposition of lithium metal. More importantly, this electrolyte exhibited excellent antioxidant properties, enabling Li||NCM811 coin cells to maintain 80% of their capacity after 300 cycles at an ultra-high cut-off voltage of 4.8 V. Furthermore, under harsh conditions of high cathode loading (30 mg cm-2), low N/P ratio (1.18), and lean electrolyte (2.3 g Ah-1), a 4.8 V-class lithium metal pouch cell with an energy density of 462.2 Wh kg-1 could stably cycle for 110 times.