SO2 Electrolyte Rechargeable Cell for High-Voltage Stability
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Solution Overview
Problem
Existing rechargeable lithium-ion cells face issues with electrolyte decomposition due to oxidative and reductive processes, flammability, and instability, leading to safety risks and reduced energy density, especially when overcharged, and require precise charging protocols and costly manufacturing measures to mitigate these issues.
Innovation Solution
A rechargeable battery cell with an SO2-based electrolyte containing a first conducting salt with specific alkali or alkaline earth metals and a layered oxide positive electrode, which forms a solvate complex with SO2 to enhance ion mobility, stability, and resistance to oxidative decomposition, and includes a stable negative electrode coating to prevent reductive decomposition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If organic solvent-based electrolytes are used in lithium-ion cells, then ionic conductivity and charge transport are achieved, but oxidative decomposition occurs at high cell voltages leading to electrolyte failure and safety risks
Solution Approach 1:
The patent changes the chemical composition parameters of the electrolyte by replacing organic solvents with inorganic carbonates (EC, PC, GC) and specifically incorporating sulfur dioxide (SO2) as a key component. This parameter change transforms the electrolyte's oxidation resistance while maintaining ionic conductivity, allowing operation at higher cell voltages without decomposition
Solution Approach 2:
The patent creates a composite electrolyte system combining multiple inorganic carbonate solvents (EC, PC, GC) with conducting salts (LiClO4, CF3SO3Li, LiBF4, LiPF6) and sulfur dioxide. This composite approach leverages the complementary properties of each component: EC provides high dielectric constant, PC/GC provide low viscosity, and SO2 provides exceptional oxidation resistance, achieving both stability and conductivity
2Use of energy by moving object
If cell voltage is increased to improve energy density, then electrical energy per unit volume increases, but electrolyte decomposition voltage is exceeded causing irreversible destruction
Solution Approach 1:
The patent changes the electrochemical stability window parameter of the electrolyte by introducing sulfur dioxide and inorganic carbonates, extending the maximum operating voltage from typical organic electrolyte limits (~4.2V) to above 4.8V. This enables higher energy density through increased cell voltage without compromising electrolyte stability
Solution Approach 2:
The electrolyte composition is specifically designed with SO2 and inorganic carbonates that preemptively resist oxidative attacks at high potentials. The forming process creates a stable SEI layer on electrodes that prevents further electrolyte decomposition, allowing the cell to operate safely at elevated voltages that would decompose conventional organic electrolytes
3Reliability
If precise charging protocols and costly manufacturing measures are implemented to prevent electrolyte decomposition, then cell reliability improves, but manufacturing complexity and cost increase
Solution Approach 1:
The electrolyte system performs self-protection through spontaneous formation of a stable solid electrolyte interface (SEI) layer during initial charging cycles. This self-formed protective layer prevents further electrolyte decomposition at high voltages, eliminating the need for complex external protection circuits or precise charging protocol control. The electrolyte essentially protects itself against oxidation through its inherent chemical stability
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 SO2-based electrolyte provides a wide electrochemical window, high energy density, improved stability against water, and increased service life, reducing self-discharge and enhancing operational reliability with fewer charge-discharge cycles.
Implementation Method 1
The electrolyte is based on SO2 and comprises at least one first conducting salt... which forms a solvate complex with SO2 to enhance ion mobility, stability, and resistance to oxidative decomposition
Implementation Method 2
At least one ion of the conducting salt (anion or cation) is sufficiently mobile in the electrolyte such that a charge transport between the electrodes, required for the functioning of the rechargeable battery cell, can take place through ionic conduction
Implementation Method 3
The electrolyte is oxidatively electrochemically decomposed from a certain upper cell voltage of the rechargeable battery cell
Implementation Method 4
Reductive processes can also decompose the electrolyte when falling below a certain cell voltage
Data Source
AI summary
This disclosure relates to a rechargeable battery cell having an active metal, at least one positive electrode, at least one negative electrode, a housing and an electrolyte, the positive electrode comprising at least one compound in the form of a layered oxide as an active material and the electrolyte being based on SO2 and comprising at least one first conducting salt which has the formula (I),M being a metal selected from the group formed by alkali metals, alkaline earth metals, metals of group 12 of the periodic table of the elements, and aluminum; x being an integer from 1 to 3; the substituents R1, R2, R3 and R4 being selected independently of one another from the group formed by C1-C10 alkyl, C2-C10 alkenyl, C2-C10 alkynyl, C3-C10 cycloalkyl, C6-C14 aryl and C5-C14 heteroaryl; and Z being aluminum or boron.