Li/FeS2 Battery Electrolyte Volume for Sustained Ion Transport
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Solution Overview
Problem
Primary lithium batteries, such as Li/FeS2 cells, experience performance degradation due to insufficient electrolyte volume, which fails to fill cathode pores and transport Li ions effectively as the battery discharges, leading to increased void volume and reduced ion transport capabilities.
Innovation Solution
Increasing the electrolyte volume beyond the theoretical minimum required to fill cathode and separator pores, ensuring full contact with the active cathode surface and maintaining ion transport throughout the discharge process, with a specific electrolyte to cathode active material ratio of at least 0.33 ml/g to 0.5 ml/g, and using a separator with optimized porosity and thickness to enhance performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the electrolyte volume is kept at the theoretical minimum to fill pores, then the battery structure is compact and material usage is efficient, but the battery performance degrades due to insufficient ion transport capability during discharge
Solution Approach 1:
The patent pre-calculates the void volume that will be generated during discharge based on the electrochemical reaction stoichiometry and density changes. The electrolyte volume is then adjusted in advance to compensate for this predicted void volume, ensuring sufficient ion transport capability throughout the entire discharge process rather than just filling initial pores.
Solution Approach 2:
The patent changes the electrolyte volume parameter from the traditional theoretical minimum (based only on pore filling) to a calculated value that accounts for discharge-induced void volume. This parameter adjustment optimizes ion transport while maintaining material efficiency.
2Reliability
If the electrolyte volume is increased to compensate for void volume during discharge, then ion transport and battery performance are maintained, but the battery becomes less compact and uses more material
Solution Approach 1:
The patent performs preliminary calculations of the void volume that will be generated during discharge based on known electrochemical reaction stoichiometry and material densities. This allows precise determination of the additional electrolyte volume needed, avoiding excessive electrolyte addition and maintaining compact battery design.
Solution Approach 2:
The patent uses theoretical calculations and modeling to predict void volume generation, replacing the need for extensive experimental trial-and-error to determine optimal electrolyte volumes. This computational approach streamlines the design process.
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 approach maintains or improves battery performance by ensuring sufficient electrolyte volume to compensate for the increased void volume during discharge, maintaining ion transport and overall cell efficiency.
Implementation Method 1
An electrolyte in contact with the anode and the cathode contains ions that flow through the separator between the electrodes to maintain charge balance throughout the battery during discharge
Implementation Method 2
The anode contains an active material that can be oxidized; the cathode contains or consumes an active material that can be reduced
Implementation Method 3
the cathode contains or consumes an active material that can be reduced
Implementation Method 4
permitting the respective oxidation and reduction reactions to occur to provide electrical power
Data Source
AI summary
A battery includes a housing, and within the housing, an anode having an alkali metal as the active material, a cathode having a mass (m) of a cathode active material, for example, iron disulfide as the active material, a separator between the anode and the cathode, and an increased electrolyte volume (v).