Titanate Negative Electrode Mn Compound Layer for Capacity Retention
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Nonaqueous electrolyte batteries using titanate metal oxide as the negative electrode face significant capacity deterioration due to SOC deviation and side reactions caused by the flat operating voltage and functional groups on the surface of the negative electrode active material, leading to increased resistance and reduced lithium ion diffusion.
Innovation Solution
The use of a titanium-containing metal oxide with a specific Mn concentration and ratio on the surface of the negative electrode active material, combined with a high temperature treatment to form a stable Mn compound layer, which suppresses side reactions and maintains lithium diffusivity, is employed to enhance the battery's capacity retention and cycle characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If titanate metal oxide is used as the negative electrode active material, then the battery exhibits excellent cycle characteristics and high safety, but the cell capacity significantly deteriorates due to SOC deviation and side reactions
Solution Approach 1:
The patent applies local quality by creating a Mn compound layer specifically on the surface of the titanate metal oxide particles. This surface modification targets only the region where side reactions occur most frequently, leaving the bulk material properties intact. The Mn compound layer acts as a protective interface that suppresses harmful reactions between the electrolyte and functional groups on the titanate surface, thereby preventing capacity deterioration while preserving the excellent cycle characteristics of the bulk titanate material.
Solution Approach 2:
The Mn compound layer serves as an intermediary between the titanate metal oxide and the nonaqueous electrolyte. This intermediate layer mediates the interaction by providing a stable interface that prevents direct contact between the electrolyte and reactive functional groups on the titanate surface. The Mn compound acts as a buffer zone that suppresses side reactions and prevents SOC deviation, allowing the underlying titanate material to maintain its excellent cycle performance without suffering from capacity deterioration.
2Use of energy by moving object
If the operating voltage is flat due to two-phase coexisting system, then the battery achieves high energy density, but side reactions occur due to functional groups on the surface of the negative electrode active material
Solution Approach 1:
The patent converts the harmful effect of functional groups on the titanate surface into a beneficial outcome by using high-temperature treatment to transform these reactive groups into a stable Mn compound layer. The high-temperature treatment causes Mn from the electrolyte to deposit and react with the functional groups, forming a protective Mn compound coating. This process transforms the original harmful reactive sites into a beneficial stable interface that suppresses further side reactions while allowing the flat voltage platform to be maintained for high energy density.
3Reliability
If high temperature treatment is applied to form Mn compound layer, then capacity retention is improved, but manufacturing complexity increases
Solution Approach 1:
The patent applies preliminary action by incorporating the Mn compound layer formation step into the initial battery manufacturing process. The high-temperature treatment is performed during the battery assembly process, specifically after the electrodes are assembled but before the battery is put into service. This preliminary formation treatment ensures that the protective Mn compound layer is already in place before the battery undergoes normal cycling, thereby improving capacity retention from the outset without requiring additional maintenance or processing steps later in the battery lifecycle.
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 approach significantly improves the capacity retention of nonaqueous electrolyte batteries by reducing resistance and maintaining lithium ion diffusion, achieving a capacity retention of up to 99.8% after 100 charge and discharge cycles.
Implementation Method 1
lithium ion diffusion
Implementation Method 2
high temperature treatment to form a stable Mn compound layer
Data Source
AI summary
A nonaqueous electrolyte battery comprising:a positive electrode including a positive electrode active material layer containing a lithium iron manganese phosphate composite having an olivine structure; anda negative electrode including a negative electrode active material layer containing a titanium-containing metal oxide composite,wherein an atomic concentration of manganese is 1 atm % or more and 15 atm % or less in a region from a surface to a depth D of the negative electrode active material layer and the depth D is more than 0 nm and 10 nm or less.