Monoclinic Composite Oxide Negative Electrode for Battery Safety
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Solution Overview
Problem
Nonaqueous electrolyte batteries using carbon-based negative electrodes face issues with dendrite precipitation and lower energy density due to rapid charge-and-discharge cycles, while titanium oxide-based batteries have lower voltage and higher potential, making them unsuitable for high-voltage applications.
Innovation Solution
A composite oxide with a monoclinic crystal structure, represented by the formula LiwNa2−xM1yTi6-zM2zO13+δ, is used as the negative electrode material, allowing for high energy density and rapid charge-and-discharge capabilities by optimizing lithium ion movement and electrode potential.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If carbon-based negative electrode is used for rapid charge-and-discharge, then charge-and-discharge speed is improved, but dendrite precipitation occurs causing safety issues
Solution Approach 1:
The invention changes the material parameter of the negative electrode from carbon-based materials to metal composite oxides (specifically titanium oxide and its composites). This fundamental material substitution resolves the contradiction by providing a surface that enables rapid lithium ion insertion/extraction without the dendrite formation problems associated with carbon-based electrodes, thus achieving both high speed and safety.
Solution Approach 2:
The invention employs composite materials, specifically metal composite oxides combining titanium oxide with other metals or compounds. These composite structures optimize both the electrochemical performance for rapid charge-and-discharge and the structural stability to prevent dendrite precipitation, simultaneously addressing speed and reliability requirements.
2Reliability
If titanium oxide is used as negative electrode active material, then rapid charge-and-discharge and long life are achieved, but energy density is reduced
Solution Approach 1:
The invention modifies the electrochemical parameters of titanium oxide by forming composites with other metals and compounds. This changes the potential characteristics and capacity of the negative electrode, optimizing the energy density while preserving the long-term reliability and rapid charge-and-discharge capabilities of the titanium oxide base material.
Solution Approach 2:
By creating metal composite oxides that combine titanium oxide with other functional materials, the invention achieves synergistic effects where the composite structure provides both the stability for long-term reliability and enhanced capacity for improved energy density, resolving the contradiction between these two parameters.
3Reliability
If material with high potential based on metal lithium is used, then voltage is reduced, but this increases battery series number for high-voltage applications
Solution Approach 1:
The invention changes the potential parameter of the negative electrode material by using metal composite oxides with optimized composition ratios. This adjustment increases the operating voltage of the battery while maintaining the stability benefits of titanium oxide-based materials, thereby reducing the number of series connections needed for high-voltage applications and simplifying the overall battery pack structure.
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 composite oxide enables a nonaqueous electrolyte battery with improved energy density, stable rapid charge-and-discharge characteristics, and controlled charge-and-discharge state management, suitable for high-voltage applications.
Implementation Method 1
The potential of titanium oxide is due to the oxidation-reduction reaction between Ti3+ and Ti4+ when lithium is electrochemically inserted and extracted
Implementation Method 2
electrons and lithium ions must be able to migrate rapidly between the positive electrode and the negative electrode
Data Source
AI summary
According to one embodiment, there is provided an active material. The active material includes a composite oxide having a monoclinic crystal structure and represented by a general formula of LiwNa2−xM1yTi6-zM2zO13+δ. In the general formula, M1 is at least one metallic element selected from the group consisting of Mg, Sr, Ca, Ba, Cs and K. M2 is at least one metallic element selected from the group consisting of Zr, Sn, V, Nb, Ta, Mo, W, Fe, Co, Mn and Al. The subscript w is within a range of 0≤w≤6. The subscript x is within a range of 0≤x<2. The subscript y is within a range of 0≤y<2. The subscript z is within a range of 0<z≤6. The subscript δ is within a range of −0.1≤δ≤0.1.