Thiophosphate Electrolyte Additive for High-Temperature Li-Ion Cells
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current lithium-ion battery electrolytes face challenges in maintaining stability and safety at high temperatures, particularly for high-voltage batteries, due to electrolyte oxidation and SEI layer breakdown, leading to capacity loss and safety risks during storage and cycling.
Innovation Solution
Incorporating a thiophosphate ester additive with an unsaturated terminal group into the electrolyte, combined with an aprotic organic solvent system and a metal salt, to form a stable electrode-electrolyte interface that reduces gas generation and enhances ionic conductivity, thereby improving high-temperature performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional carbonate-based electrolytes are used in high-voltage Li-ion batteries, then ionic conductivity and charge transport are maintained, but electrolyte oxidation occurs leading to gas generation and capacity loss at high temperatures
Solution Approach 1:
The thiophosphate ester additive acts as an intermediary substance that preferentially reacts with electrode materials and electrolyte components to form a protective interface layer. This mediator prevents direct harmful interactions between the electrolyte and electrodes at high temperatures, thereby reducing gas generation while maintaining ionic conductivity.
Solution Approach 2:
The invention changes the chemical composition parameter of the electrolyte by introducing thiophosphate ester with specific molecular structure (containing P=S bond and unsaturated terminal group). This parameter change transforms the electrolyte's interfacial chemistry, enabling formation of a stable protective layer that suppresses oxidation reactions and gas evolution at elevated temperatures.
2Quantity of substance
If high-voltage cathode materials are used to increase energy density, then capacity and driving range are improved, but cathode material dissolution in electrolyte increases leading to structural breakdown and interfacial resistance
Solution Approach 1:
The thiophosphate ester additive serves as a protective intermediary that forms a stable interfacial layer between the high-voltage cathode material and electrolyte. This intermediary layer prevents direct contact and dissolution of cathode materials in the electrolyte, thereby maintaining cathode structural stability and reducing interfacial resistance while preserving high energy density.
Solution Approach 2:
The invention converts the potentially harmful dissolution reaction into a beneficial process by controlling the initial reaction to form a protective interface layer. The thiophosphate ester undergoes controlled decomposition to create a stable coating that prevents further harmful interactions, transforming the harmful dissolution tendency into a protective mechanism.
3Reliability
If traditional SEI forming additives are used to passivate the anode, then anode protection is achieved, but the SEI layer breaks down at high temperatures causing irreversible reactions and capacity loss
Solution Approach 1:
The thiophosphate ester additive creates a composite SEI layer structure that combines the benefits of traditional SEI forming additives with the thermal stability of thiophosphate compounds. This composite interface structure maintains anode passivation at operating temperatures while providing enhanced thermal stability to prevent SEI breakdown during high-temperature storage and cycling.
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 thiophosphate ester additive enhances the stability and safety of high-voltage lithium-ion batteries at elevated temperatures by forming a robust SEI and reducing irreversible reactions, leading to improved cycle life and capacity retention.
Implementation Method 1
form a stable SEI layer
Implementation Method 2
electrochemical oxidation of the material
Implementation Method 3
The shuttling of positive and negative ions between the battery electrodes is the main function of the electrolyte
Implementation Method 4
thiophosphate ester additive with an unsaturated terminal group
Data Source
AI summary
The present disclosure relates to a phosphorus additive that is useful for stable cycling and storage of lithium ion cells at high temperatures, an electrolyte containing the phosphorus additive, and an electrochemical energy storage device containing the electrolyte. An electrolyte includes an aprotic organic solvent system; a metal salt; and at least one thiophosphate additive having an unsaturated terminal group, according to the formula: