Nonaqueous Battery Void Volume Control for High-Rate Cycling
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Solution Overview
Problem
Nonaqueous electrolyte secondary batteries face issues with non-uniform charge carrier density and concentration during high-rate charging and discharging, leading to increased internal resistance due to varying void volumes in active material layers.
Innovation Solution
The void volume of the positive and negative electrode active material layers is adjusted within specific ranges (1.00≦α≦2.20 cm3/Ah and 2.17≦β≦3.27 cm3/Ah, with α<β) to ensure uniform charge carrier distribution and reduce internal resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the void volume in active material layers is increased to improve charge carrier movement, then output performance is improved, but the pumping action during high-rate charging and discharging causes excessive electrolytic solution extrusion, leading to non-uniform charge carrier density and increased internal resistance
Solution Approach 1:
The patent applies parameter changes by precisely controlling the void volume of active material layers within specific ranges (0.03≤void volume of positive electrode<0.06 cm³/Ah and 0.06≤void volume of negative electrode<0.09 cm³/Ah). This quantitative control of void volume parameters balances charge carrier movement efficiency with prevention of excessive electrolytic solution extrusion during high-rate charging and discharging, thereby improving both output performance and high-rate cycle characteristics
2Productivity
If high current flows at high charging rates to improve productivity, then charging speed is improved, but non-uniform charge carrier distribution occurs, causing increased internal resistance
Solution Approach 1:
The patent controls the void volume parameters of active material layers to specific ranges that enable uniform charge carrier distribution even during high-rate charging and discharging. This parameter control ensures that the battery can operate at high charging rates while maintaining stable internal resistance and avoiding non-uniform charge carrier concentration
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This adjustment results in reduced charge transfer resistance, maintaining a low initial resistance and minimizing the increase in internal resistance even after repeated high-rate charging and discharging, thereby enhancing high-rate cycle characteristics.
Implementation Method 1
The battery is charged and discharged by the charge carriers moving between the active materials of the positive and negative electrodes through a nonaqueous electrolytic solution impregnated into the voids
Implementation Method 2
an excess amount of nonaqueous electrolytic solution may be extruded from an active material layer due to, for example, an effect of a pumping action working along with the expansion and contraction of an active material
Data Source
AI summary
A nonaqueous electrolyte secondary battery includes: a positive electrode that includes a positive electrode active material layer; a negative electrode that includes a negative electrode active material layer; and a nonaqueous electrolytic solution. When a void volume of the positive electrode active material layer per battery capacity is represented by α (cm3/Ah), and when a void volume of the negative electrode active material layer per battery capacity is represented by β (cm3/Ah), the following conditions are satisfied:1.00≦α≦2.20; (1)2.17≦β≦3.27; and (2)α<α. (3)