Li-Rich Cathode Electrolyte Additives for Interface-Stable Batteries
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Solution Overview
Problem
Existing lithium-ion batteries experience reduced reliability due to side reactions at the interface between the positive electrode active material and the electrolytic solution, leading to instability and insufficient capacity when a large amount of Li is extracted.
Innovation Solution
A battery design featuring a positive electrode active material with a crystal structure belonging to the FM3-M space group, represented by Compositional Formula LixMeyOαFβ, where Me includes elements like Mn, Co, Ni, and F, and an electrolytic solution with additives such as dinitrile and diisocyanate compounds, which prevent side reactions by adhering to the surface of the active material.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a large amount of Li is extracted from the positive electrode active material, then the battery capacity increases, but side reactions occur at the interface between the positive electrode active material and the electrolytic solution, reducing reliability
Solution Approach 1:
The patent introduces an intermediary substance (coating layer or surface modification agent) between the positive electrode active material and the electrolytic solution. This intermediary prevents direct contact and side reactions at the interface, allowing large amounts of Li to be extracted without compromising reliability. The coating layer acts as a protective mediator that maintains interface stability while enabling high capacity operation.
Solution Approach 2:
The patent modifies the surface properties or chemical composition parameters of the positive electrode active material through coating or surface treatment. By changing these parameters, the material achieves both high Li extraction capability and improved interface stability, resolving the contradiction between capacity and reliability.
2Quantity of substance
If the positive electrode active material undergoes significant Li extraction, then the battery achieves high capacity, but the crystal structure becomes unstable
Solution Approach 1:
The patent creates a composite structure where the positive electrode active material is combined with stabilizing components (coating layers or surface-modified phases). This composite approach allows the core material to provide high capacity through Li extraction while the outer stabilizing components maintain crystal structure integrity during cycling.
Solution Approach 2:
The patent applies surface coating or pre-treatment to the positive electrode active material before battery operation. This beforehand protection creates a buffer that prevents structural degradation during Li extraction, allowing the material to sustain high capacity cycling without crystal structure collapse.
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 configuration enhances the reliability and capacity of the battery by preventing side reactions, maintaining structural stability even when a large amount of Li is extracted, resulting in a high-capacity lithium-ion battery with improved discharge efficiency.
Implementation Method 1
an electrolytic solution with additives such as dinitrile and diisocyanate compounds, which prevent side reactions by adhering to the surface of the active material
Data Source
AI summary
A battery includes a positive electrode including a positive electrode active material, a negative electrode, and an electrolytic solution including an additive. The positive electrode active material includes a compound having a crystal structure belonging to a space group FM3-M and represented by Compositional Formula (1): LixMeyOαFβ, where, Me is one or more elements selected from the group consisting of Mn, Co, Ni, Fe, Al, B, Ce, Si, Zr, Nb, Pr, Ti, W, Ge, Mo, Sn, Bi, Cu, Mg, Ca, Ba, Sr, Y, Zn, Ga, Er, La, Sm, Yb, V, and Cr; and subscripts x, y, α, and β satisfy the following requirements: 1.7≤x≤2.2, 0.8≤y≤1.3, 1≤α≤2.5, and 0.5≤β≤2. The additive is at least one selected from dinitrile compounds and diisocyanate compounds.