Lithium Primary Battery Negative Electrode Tape Adhesion
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Solution Overview
Problem
Lithium primary batteries with a manganese dioxide positive electrode and a lithium negative electrode face issues where the nonaqueous electrolyte enters the adhesive voids, degrading the adhesive force and causing the tape to float, leading to lithium elution and reduced capacity at the end of discharge, which degrades the negative electrode's collector function.
Innovation Solution
A lithium primary battery design featuring a nonaqueous electrolyte with a specific lithium salt additive, such as LiPO2F2 or LiBC2O4F2, and a tape with a resin substrate and adhesive layer, adhered to the negative electrode, which suppresses the dissolution reaction and maintains the collector function by inhibiting electrolyte entry into the adhesive voids and improving adhesion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a tape is adhered to the lithium negative electrode to suppress dissolution reaction, then the collector function is maintained, but the nonaqueous electrolyte enters the adhesive voids causing the tape to float and lithium elution
Solution Approach 1:
The patent introduces a specific additive (lithium salt with phosphorus or boron) as an intermediary substance in the nonaqueous electrolyte. This additive mediates between the electrolyte and the adhesive by preferentially occupying the adhesive voids, preventing the electrolyte from directly contacting and degrading the adhesive. The additive acts as a protective intermediary that maintains the tape adhesion while allowing ionic conductivity.
Solution Approach 2:
The patent changes the chemical composition parameters of the nonaqueous electrolyte by incorporating specific lithium salts (LiPO2F2, LiBF4, LiPF6) at controlled concentrations (0.01-1.0 mol/L). This parameter change modifies the electrolyte's interaction with the adhesive, reducing its harmful effects while maintaining electrical conductivity. The specific molecular structure parameters of the additive are optimized to achieve the desired protective effect.
2Reliability
If the tape width is increased to improve adhesion coverage, then the collector function is enhanced, but the lithium dissolution reaction is excessively inhibited reducing capacity output
Solution Approach 1:
The patent applies local quality by using a narrow tape (0.5-3 mm width) positioned specifically along the longitudinal center line of the negative electrode. This localized approach provides adhesion support where most needed (center region) while leaving the edges exposed for lithium dissolution. The additive in the electrolyte provides localized protection at the adhesive interface, allowing the tape to be narrow without compromising overall collector function.
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
The solution effectively maintains the negative electrode's collector function and capacity throughout discharge, with the tape width optimized between 0.5 to 3 mm to prevent excessive inhibition of lithium dissolution and ensure high capacity output.
Implementation Method 1
a dissolution reaction of the lithium negative electrode under the tape is suppressed during the discharge
Implementation Method 2
the tape includes a resin substrate and an adhesive layer
Data Source
AI summary
A lithium primary battery including: a battery case; an electrode group; and a nonaqueous electrolyte; the nonaqueous electrolyte contains a nonaqueous solvent, a solute, and an additive; the electrode group includes a positive electrode, a negative electrode, and a separator interposed therebetween; the negative electrode includes foil composed of metal lithium or a lithium alloy, has a shape extending in a longitudinal direction and a short direction, and provided with a long tape adhered to at least one main surface of the negative electrode along the longitudinal direction thereof; the tape includes a resin substrate and an adhesive layer and has a width of 0.5 to 3 mm; and the additive is a lithium salt represented by the following formula (1): LixMCyOzFα (1≤x≤2, 0≤y≤6, 0≤z≤8, 0≤α≤6, and 1≤y+z+α are satisfied, and y and z are not simultaneously 0), and the element M includes at least one of phosphorus and boron.