Cylindrical Battery Electrode Layout for High-Capacity Output
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Solution Overview
Problem
Existing cylindrical secondary batteries face challenges in improving battery capacity per unit volume and output characteristics when increasing size, as they tend to lack electrolyte liquid at the winding center, leading to deteriorated output characteristics.
Innovation Solution
The use of a lithium-containing composite oxide with a layered rock-salt structure and a sulfonate compound on its surface, combined with a positive electrode mixture layer basis weight of 250 g/m² and multiple positive electrode leads, enhances Li ion mobility and reduces connecting resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the battery size is increased to improve battery capacity per unit volume, then the battery capacity increases, but the output characteristics deteriorate due to insufficient electrolyte liquid at the winding center
Solution Approach 1:
The patent applies local quality by providing multiple positive electrode leads at specific positions (radially spaced apart) to create localized current collection points. This ensures adequate electrolyte distribution and current collection throughout the winding center region, resolving the output characteristic deterioration that occurs when battery size increases and the winding center becomes electrolyte-deficient
2Quantity of substance
If the positive electrode mixture layer basis weight is increased to 250 g/m² or more to improve capacity, then the battery capacity per unit volume increases, but the internal resistance increases leading to worsened output characteristics
Solution Approach 1:
The patent segments the current collection function by providing multiple positive electrode leads (at least three) spaced radially apart around the winding center. This segmentation reduces the current density and resistance at each individual lead connection point, allowing the use of heavier positive electrode mixture layers (250 g/m² or more) without compromising output characteristics, thereby achieving high capacity per unit volume while maintaining low internal resistance
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 configuration achieves both increased battery capacity per unit volume and improved output characteristics by optimizing electrolyte distribution and reducing internal resistance.
Implementation Method 1
the positive electrode active material includes a lithium-containing composite oxide having a layered rock-salt structure and a sulfonate compound present on a surface of the lithium-containing composite oxide
Implementation Method 2
a positive electrode active material includes a lithium-containing composite oxide having a layered rock-salt structure
Data Source
AI summary
This cylindrical secondary battery comprises: an electrode body having a positive electrode and a negative electrode; a bottomed cylindrical exterior body, having an outer diameter of 25 mm or more; and a sealing body. The positive electrode includes a positive-electrode current collector, and a positive-electrode mixture layer, the positive-electrode mixture layer containing a positive-electrode active material and a sulfonic acid compound represented by general formula (I). The positive-electrode active material includes a lithium-containing composite oxide having a layered rock-salt structure. The weight per unit area of the positive-electrode mixture layer is 250 g/m2 or more. In the electrode body, three or more positive-electrode leads are led out.(In the formula, A is a group 1 element or a group 2 element, R is a hydrocarbon group, and n is 1 or 2.)