Alkaline Dry Battery Positive Electrode Taper to Prevent Cracking
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Solution Overview
Problem
Increasing the filling height of the positive electrode in alkaline dry batteries leads to increased cracking due to the transmission of impact during groove formation, which affects discharge performance.
Innovation Solution
The positive electrode pellets are designed with a tapered part that decreases in outer diameter from the bottom to the opening, with a specific inclination angle (0.26° to 0.87°) and a distance between the groove and the electrode end face (0.55 mm to 2.35 mm) to minimize cracking while increasing capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the filling height of the positive electrode is increased to increase capacity, then the capacity increases, but the distance between the groove and the end face of the positive electrode becomes small, causing impact transmission during groove formation to lead to cracking of the positive electrode
Solution Approach 1:
The positive electrode is designed with non-uniform structure: a tapered part with smaller outer diameter is provided at the end face closer to the groove, while other parts maintain larger diameter. This local variation in geometry reduces impact transmission at the critical location (end face near groove) during groove formation, suppressing cracking while maintaining overall capacity through sufficient filling height
Solution Approach 2:
The tapered part is pre-formed on the positive electrode before the groove formation process. This preliminary geometric modification creates a stress-distributing structure that prevents cracking during the subsequent groove formation operation, allowing the electrode to withstand the impact without damage
Data Source
AI summary
A method for manufacturing an alkaline dry battery includes first to third steps. In the first step, a hollow cylindrical first positive electrode pellet including a first end face and a second end face is prepared in an axial direction is prepared. In the second step, a hollow cylindrical positive electrode pellet group including the first positive electrode pellet is inserted into a case to obtain a positive electrode inscribed in the case. At this time, the first positive electrode pellet is disposed on the most opening side of the case such that the first end face faces an opening side of the case. In the third step, an annular groove is provided in a side part of the case. The first positive electrode pellet includes a tapered part whose outer diameter decreases from the second end face toward the first end face, and in a cross section along the axial direction of the first positive electrode pellet, an inclination angle θ of the tapered part with respect to an axis of the first positive electrode pellet ranges from 0.26° to 0.87°, inclusive. A distance h between the groove and the first end face ranges from 0.55 mm to 2.35 mm, inclusive.