Monoclinic Complex Oxide Anode for High-Capacity Rapid Charge Batteries
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Solution Overview
Problem
Nonaqueous electrolyte secondary batteries using carbon-based materials face issues with rapid charge/discharge leading to dendrite precipitation and safety concerns, while titanium-based oxides offer stable rapid charge/discharge but have lower energy density and capacity due to limited lithium-absorbing sites.
Innovation Solution
A monoclinic complex oxide represented by LixTi1−yM1yNb2−zM2zO7+δ is used as the negative electrode active material, which provides a crystal structure with two-dimensional channels for lithium ion diffusion, increasing capacity and energy density by allowing more lithium insertion and maintaining structural stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If carbon-based material is used in the negative electrode, then capacity per mass is high, but dendrite precipitation occurs during rapid charge/discharge causing safety issues
Solution Approach 1:
The patent uses a composite oxide material (Li4Ti5O12 or Li2TiO3) that combines the advantages of both carbon-based materials and titanium-based oxides. This composite structure provides high capacity per mass like carbon materials while preventing dendrite precipitation through the stable crystal structure of the composite oxide, thus resolving the safety issue during rapid charge/discharge.
Solution Approach 2:
The patent changes the electrochemical potential parameter by using a composite oxide with a potential of approximately 1.55 V vs. Li/Li+, which is lower than conventional titanium-based oxides. This parameter change allows for higher capacity utilization while maintaining structural stability that prevents dendrite formation during rapid charge/discharge cycles.
2Productivity
If titanium-based oxide is used in the negative electrode, then rapid charge/discharge performance is stable, but energy density is lower
Solution Approach 1:
The patent changes the electrochemical potential parameter from the conventional 1.5 V to approximately 1.55 V vs. Li/Li+ by using a composite oxide structure. This parameter optimization enables higher capacity per mass (170 mAh/g or more) while maintaining the structural stability needed for rapid charge/discharge performance, thus improving energy density without sacrificing productivity.
3Quantity of substance
If lithium insertion is increased to improve capacity, then energy density improves, but structural stability decreases
Solution Approach 1:
The patent employs a composite oxide material with a specific crystal structure (spinel structure for Li4Ti5O12 or layered structure for Li2TiO3) that provides both high lithium insertion capacity and structural stability. The composite structure allows up to 170 mAh/g capacity while the stable crystal framework prevents degradation during repeated lithium insertion and extraction cycles.
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 monoclinic complex oxide enables high capacity and rate performance, improving energy density and charge/discharge efficiency while reducing lithium loss, resulting in a battery with excellent repetitive rapid charge/discharge capabilities and high energy storage.
Implementation Method 1
The potential of titanium based oxide is due to the redox reaction between Ti3+ and Ti4+ when lithium is electrochemically inserted and released
Implementation Method 2
a crystal structure with two-dimensional channels for lithium ion diffusion, increasing capacity and energy density by allowing more lithium insertion
Data Source
AI summary
According to one embodiment, a battery active material is provided. The battery active material includes monoclinic complex oxide represented by the formula LixTi1−yM1yNb2−zM2zO7+δ (0≤x≤5, 0≤y≤1, 0≤z≤2, −0.3≤δ≤0.3). In the above formula, M1 is at least one element selected from the group consisting of Zr, Si and Sn, and M2 is at least one element selected from the group consisting of V, Ta and Bi.