Spinel Positive Electrode Coated with Inorganic Solid Electrolyte
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Solution Overview
Problem
Non-aqueous electrolyte secondary batteries with inorganic solid electrolyte coatings on positive electrode active materials face durability issues due to film deterioration from the expansion and contraction of the active material during charge and discharge, leading to reduced cycle characteristics.
Innovation Solution
A lithium-containing composite oxide with a spinel structure, containing Ti and/or Mg, is used as the positive electrode active material, coated with an inorganic solid electrolyte film, which reduces the volume change of the active material during charging and discharging, thereby preventing film deterioration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the surface of positive electrode active material is coated with inorganic solid electrolyte, then decomposition reaction of electrolyte solution is suppressed, but film deteriorates due to expansion and contraction of active material during charge and discharge
Solution Approach 1:
The invention changes the compositional parameters of the spinel structure by incorporating additional elements (Fe, Co, Ni, Mn, Al, Ti, Mg, Zn, or In) in specific amounts. This parameter modification reduces the volume change of the positive electrode active material during charge and discharge, thereby preventing film deterioration while maintaining decomposition suppression functionality
Solution Approach 2:
The invention creates a composite structure by coating the spinel-type lithium-containing composite oxide with an inorganic solid electrolyte film. This composite material approach combines the decomposition suppression capability of the solid electrolyte coating with the improved volume stability of the modified spinel structure
2Use of energy by moving object
If high-voltage operation is implemented, then energy density is improved, but electrolyte decomposition increases
Solution Approach 1:
The inorganic solid electrolyte coating acts as an intermediary layer between the positive electrode active material and the liquid electrolyte solution. This intermediate film prevents direct contact and decomposition reactions, enabling high-voltage operation (4.3V or higher) without excessive electrolyte decomposition
3Stability of the object's composition
If additional elements are added to spinel structure, then volume change is reduced, but manufacturing complexity increases
Solution Approach 1:
The invention modifies the compositional parameters of the spinel structure by adding specific elements in controlled amounts (0.01-1.0 mol each). These parameter changes achieve volume stability while maintaining a relatively simple manufacturing process through conventional solid-state reaction methods
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 enhances the durability of the battery by minimizing film degradation and improving cycle characteristics, as evidenced by increased capacity retention rates.
Implementation Method 1
coating the surface of a positive electrode active material with a lithium ion-conductive glass to reduce a contact area between the positive electrode active material and the electrolyte solution
Implementation Method 2
a lithium-containing composite oxide having a spinel structure, and contains at least one of Ti and Mg as an additional element
Data Source
AI summary
Provided is a non-aqueous electrolyte secondary battery excellent in durability, the non-aqueous electrolyte secondary battery including a positive electrode active material, the surface of which is coated with a film formed of an inorganic solid electrolyte, wherein a change in volume of the positive electrode active material during charge and discharge is reduced to prevent deterioration of the film with which the surface of the positive electrode active material is coated. In a non-aqueous electrolyte secondary battery including a positive electrode active material, the surface of which is coated with a film formed of an inorganic solid electrolyte, the positive electrode active material is a lithium-containing composite oxide having a spinel structure, and contains at least one of Ti and Mg as an additional element.