Lithium Manganese Complex Oxide Coating for High-Temperature Stability
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Solution Overview
Problem
Lithium manganese complex oxide batteries face issues with manganese dissolution in high-temperature environments, leading to storage and cycle deterioration, as existing surface modification methods either fail to inhibit manganese dissolution or increase electrode resistance.
Innovation Solution
A lithium ion battery design featuring a lithium manganese complex oxide positive electrode with a bismuth oxide and a metal compound, such as TiO2, Al2O3, ZrO2, AlF3, or BiF3, attached to its surface, where the metal compound has a lower dissolution rate than manganese, reducing direct reaction with the electrolyte and minimizing resistance increase.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the surface of lithium manganese complex oxide is modified with bismuth oxide, then manganese dissolution is temporarily suppressed, but the bismuth oxide dissolves in the electrolytic solution and loses its protective effect
Solution Approach 1:
The patent introduces an intermediary substance (coating layer comprising aluminum oxide, aluminum hydroxide, or aluminum carbonate) between the bismuth oxide and the electrolytic solution. This intermediary layer protects the bismuth oxide from direct dissolution while still allowing it to exert its manganese dissolution inhibition effect. The coating layer acts as a mediator that preserves the protective function of bismuth oxide without exposing it directly to the corrosive electrolyte environment.
Solution Approach 2:
The patent applies a thin film coating (aluminum oxide, aluminum hydroxide, or aluminum carbonate) on the surface of the positive electrode active material containing bismuth oxide. This thin film serves as a protective shell that prevents direct contact between the electrolytic solution and the bismuth oxide, thereby maintaining the structural integrity and functional durability of the surface modification over time.
2Reliability
If the entire surface of lithium manganese complex oxide is coated with Al2O3 layer, then manganese dissolution is inhibited, but lithium ion diffusion resistance increases
Solution Approach 1:
The patent applies the coating layer locally rather than uniformly covering the entire surface. By controlling the coating conditions and composition, the protective layer is formed in specific regions where manganese dissolution is most problematic, while leaving other areas accessible for lithium ion diffusion. This local application strategy maintains the beneficial protection against manganese dissolution while minimizing the harmful effect on ion transport.
Solution Approach 2:
The coating layer is designed with a porous or non-dense structure that allows lithium ions to pass through while still providing a barrier against manganese dissolution into the electrolyte. The porous structure enables selective permeability - blocking harmful manganese ions while permitting necessary lithium ion transport, thus resolving the contradiction between protection and conductivity.
3Quantity of substance
If high voltage 5 V class positive electrodes are used, then energy density increases, but reaction with electrolytic solution occurs more easily causing manganese dissolution
Solution Approach 1:
The patent creates a composite material system combining lithium manganese complex oxide (providing high voltage and energy density) with bismuth oxide and aluminum-based coating materials (providing dissolution resistance). This composite structure allows the electrode to maintain its high energy density characteristics while the additional components provide protective functions that prevent manganese dissolution, even at high operating voltages where such dissolution is more prone to occur.
Solution Approach 2:
The patent applies protective materials (bismuth oxide and aluminum-based coating) in advance to the lithium manganese complex oxide surface before the battery operates. This preliminary protection creates a barrier that prevents or reduces manganese dissolution before it can occur during high-voltage operation, thereby enabling the use of high energy density 5V class electrodes without suffering from the associated manganese dissolution problems.
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 approach effectively inhibits manganese dissolution and resistance increase, enhancing the battery's high-temperature life characteristics, particularly in 5 V class positive electrodes.
Implementation Method 1
a metal compound which is attached to part of a surface of the lithium manganese complex oxide... reducing direct reaction with the electrolyte
Implementation Method 2
The approach effectively inhibits manganese dissolution and resistance increase, enhancing the battery's high-temperature life characteristics
Data Source
AI summary
It is an object of this exemplary embodiment to provide a lithium ion battery using a lithium manganese complex oxide, in which the dissolution of manganese and resistance increase are inhibited, and which is excellent in life characteristics at high temperature. One aspect of this exemplary embodiment is a lithium ion battery comprising at least a positive electrode comprising a positive electrode active material, and an electrolytic solution, wherein the positive electrode active material is a lithium manganese complex oxide, the positive electrode comprises a bismuth oxide, and a metal compound attached to part of a surface of the lithium manganese complex oxide, and a dissolution rate of a metal of the metal compound in the electrolytic solution is lower than a dissolution rate of manganese of the lithium manganese complex oxide.