SO2 Electrolyte Lithium Battery Cell Safety
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Solution Overview
Problem
Conventional rechargeable lithium ion battery cells face safety issues due to the flammability of organic solvent electrolytes, leading to increased manufacturing costs and cell volume/weight from safety components designed to prevent combustion.
Innovation Solution
A rechargeable lithium ion battery cell design featuring a positive electrode with LiFePO4, a porous metal current collector, and an electrolyte comprising SO2 and a conductive salt, where the electrolyte contains at least 2 moles of SO2 per mole of conductive salt, and the positive electrode has a thickness of at least 0.3 mm with porosity between 0% to 50%, reducing capacity loss through stable SEI layer formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional organic solvent electrolyte is used in rechargeable lithium ion battery cells, then good electrochemical performance is achieved, but safety problems occur due to flammability
Solution Approach 1:
The patent changes the chemical composition parameters of the electrolyte by using sulfone-based solvents (dimethyl sulfone, diethyl sulfone, or their mixtures) instead of conventional organic solvents. This parameter change eliminates flammability while maintaining electrochemical performance, directly resolving the safety contradiction.
Solution Approach 2:
The patent converts the potential harm of electrolyte flammability into a benefit by selecting sulfone-based electrolytes that are inherently non-flammable. This transforms the safety risk into a safety feature, eliminating the need for additional safety components and their associated volume and weight.
2Reliability
If safety components are added to prevent combustion, then safety is improved, but manufacturing costs and cell volume/weight increase
Solution Approach 1:
The patent extracts and removes the need for additional safety components by using inherently non-flammable sulfone-based electrolytes. This eliminates the need for flame retardants, safety valves, or other combustion-prevention devices, thereby reducing manufacturing costs and simplifying cell design.
Solution Approach 2:
The sulfone-based electrolyte serves multiple functions simultaneously: it provides ionic conductivity for electrochemical operation and inherently prevents combustion without requiring additional safety additives or components. This multi-functionality reduces overall device complexity.
3Productivity
If thick electrodes are used, then manufacturing costs are reduced and capacity is maintained, but internal resistance may increase
Solution Approach 1:
The patent changes the electrolyte composition parameters to sulfone-based solvents with high dielectric constants and excellent ionic conductivity. This parameter change allows thick electrodes to maintain low internal resistance by ensuring efficient ion transport throughout the electrode thickness, resolving the contradiction between electrode thickness and 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
The design enhances safety by eliminating flammability risks, maintains discharge capacity with minimal loss over 250 cycles, and reduces manufacturing costs through thick electrodes and stable internal resistance.
Implementation Method 1
an electrolyte comprising SO2 and a conductive salt, wherein the electrolyte comprises at least 2 moles of SO2 per mole of conductive salt
Implementation Method 2
the positive electrode and/or negative electrode are treated to reduce capacity loss due to formation of stable covering layers on the positive and negative electrodes (for example, SEI layers)
Data Source
AI summary
Rechargeable lithium battery cell having a housing, a positive electrode, a negative electrode and an electrolyte containing a conductive salt, wherein the electrolyte comprises SO2 and the positive electrode contains an active material in the composition LixM′yM″z(XO4)aFb, whereinM′ is at least one metal selected from the group consisting of the elements Ti, V, Cr, Mn, Fe, Co, Ni, Cu and Zn,M″ is at least one metal selected from the group consisting of the metals of the groups II A, III A, IV A, V A, VI A, IB, IB, IIB, IVB, VB, VIB and VIIIB,X is selected from the group consisting of the elements P, Si and S,x is greater than 0,y is greater than 0,z is greater than or equal to 0,a is greater than 0 andb is greater than or equal to 0.