LMFP Battery Electrolyte Additive for Manganese Dissolution Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The John-Teller effect in lithium manganese iron phosphate batteries leads to manganese ion dissolution, causing damage to the solid electrolyte interface (SEI) film, reducing cycle stability and capacity, and accelerating side reactions at high temperatures or voltages.
Innovation Solution
Incorporating a thiophene-based additive with specific chemical structures and lone pair electrons into the electrolyte to form a stable complex with manganese ions, thereby reducing their migration and deposition, and promoting a robust SEI film formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If lithium manganese iron phosphate is used as positive electrode material, then energy density and cost are improved, but manganese ion dissolution increases at high temperatures or voltages
Solution Approach 1:
A thiophene-based additive is introduced as an intermediary substance in the electrolyte. This additive contains nitrogen, sulfur and/or oxygen elements with lone pair electrons that can complex with manganese ions, acting as a mediator to prevent direct harmful interactions between manganese ions and the electrode structures, thereby reducing manganese ion dissolution and improving cycle stability
Solution Approach 2:
The chemical composition of the electrolyte is modified by adding the thiophene-based additive with specific functional groups (amino, thienyl, pyridyl, acetyl, amido, or ester groups). This parameter change in electrolyte composition enables the additive to complex with manganese ions through lone pair electrons, effectively reducing manganese ion dissolution while maintaining the high energy density of lithium manganese iron phosphate
2Quantity of substance
If manganese ions dissolve in electrolyte, then positive electrode capacity increases initially, but side reactions accelerate and consume active lithium
Solution Approach 1:
The harmful effect of manganese ion dissolution is converted into a beneficial effect by using the dissolved manganese ions to form stable complexes with the thiophene-based additive. Instead of allowing free manganese ions to cause side reactions and consume active lithium, the additive captures them through complexation, transforming the harmful dissolved ions into benign complexed species that no longer participate in harmful side reactions
3Quantity of substance
If manganese ions migrate to negative electrode, then negative electrode capacity increases, but SEI film is destroyed and cycle life decreases
Solution Approach 1:
The thiophene-based additive serves as an intermediary that intercepts manganese ions in the electrolyte before they can migrate to and deposit on the negative electrode. The additive's lone pair electrons form complexes with manganese ions, preventing their migration and thus protecting the SEI film from destruction while avoiding the need to alter the negative electrode composition
4Power
If high voltage is applied to increase power output, then battery power increases, but John-Teller effect intensifies and manganese dissolution increases
Solution Approach 1:
The electrolyte composition is changed by introducing the thiophene-based additive, which modifies the chemical environment in the battery. This parameter change enables the electrolyte to complex with manganese ions through lone pair electrons, effectively suppressing manganese dissolution even under high voltage conditions, thereby allowing high power output without the detrimental John-Teller effect
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
Enhances cycle stability and capacity retention by mitigating manganese ion-related damage to electrodes, improving interface impedance, and extending battery life under high-temperature conditions.
Implementation Method 1
The thiophene-based additive includes a thiophene ring structure and a specific group having nitrogen, sulfur and/or oxygen elements containing lone pair electrons, and the specific group is directly connected to the thiophene ring. Therefore, the elements containing lone pair electrons in the thiophene-based additive may complex with manganese ions dissolved from the positive electrode material
Implementation Method 2
the thiophene-based additive within the above content range can promote the formation of SEI film on the surface of the negative electrode and improve the structural stability of the SEI film
Data Source
AI summary
A lithium-ion battery and an electrical device using the same are provided. The lithium-ion battery includes a positive electrode, a negative electrode and an electrolyte. The active material of the positive electrode includes lithium manganese iron phosphate. The electrolyte includes a thiophene-based additive, and the chemical structure of the thiophene-based additive satisfies the Formula I: where at least one of R1 to R4 includes at least one of an amino group, a thienyl group, a pyridyl group, an acetyl group, an amido group, and an ester group, and the thiophene-based additive is included in an amount ranging from 0.08 wt% to 2.80 wt% based on a total mass of the electrolyte.