Solid-State Li-Ion Battery Anode Composition for Capacity Detection
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Solution Overview
Problem
Accurate detection of remaining capacity in lithium ion secondary batteries using voltage measurement is challenging, particularly in batteries with solid electrolytes, due to obstacles posed by solid electrolyte particles and traditional negative electrode active materials, leading to sudden voltage drops at low capacity.
Innovation Solution
Incorporating a specific combination of spinel-type Li4-a-cTi5-bM1a+bO12−δ and M2xNb1-xO2.5-θ or M3yM41-yO3-η negative electrode active materials, with a volume ratio of the second active material between 5% to 25%, to suppress sudden voltage drops and enable accurate capacity detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If LiCoO2 and Li4Ti5O12 are used as positive and negative electrode active materials, then excellent output characteristics and durability are achieved, but sudden voltage drop occurs at end of discharge making remaining capacity detection difficult
Solution Approach 1:
The invention changes the chemical composition parameters of the negative electrode active material by introducing elements M1, M2, M3, and M4 into the Li4Ti5O12 structure, creating a composite material Li4-a-cTi5-bM1a+bO12-δ that maintains the original material's excellent output characteristics while modifying its voltage discharge profile to enable accurate remaining capacity detection
Solution Approach 2:
The invention creates a composite negative electrode active material by combining Li4Ti5O12 with other metal oxides (M2xNb1-xO2.5-θ and/or M3yM41-yO3-η) in specific ratios, where the composite structure synergistically provides both the excellent output characteristics of Li4Ti5O12 and the gradual voltage discharge behavior needed for accurate capacity detection
2Reliability
If solid electrolyte is used in the negative electrode, then battery safety is improved, but solid electrolyte particles become obstacles making conductive path improvement difficult
Solution Approach 1:
The invention applies local quality by creating specific regions within the negative electrode where Li4Ti5O12 particles are positioned to establish conductive paths, while solid electrolyte particles are distributed in the interstices, ensuring that conductive pathways are maintained locally despite the presence of solid electrolyte obstacles throughout the electrode structure
3Ease of manufacture
If traditional negative electrode active materials are used with solid electrolyte, then battery construction is simplified, but sudden voltage drop at low capacity prevents accurate detection
Solution Approach 1:
The invention modifies the voltage discharge characteristics by changing the chemical composition of the negative electrode active material, introducing elements M1, M2, M3, and M4 in controlled amounts to achieve a gradual voltage decrease at low capacity without complicating the battery construction process
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 solution allows for precise detection of remaining capacity using voltage measurement, even at low levels, by ensuring gradual voltage changes, thereby improving load characteristics and detection accuracy.
Implementation Method 1
a first negative electrode active material of spinel type Li4-a-cTi5-bM1a+bO12−δ... and a second negative electrode active material of at least one kind selected from the group consisting of M2xNb1-xO2.5-θ, and M3yM41-yO3-η
Data Source
AI summary
The lithium-ion secondary battery can easily detect remaining capacity by a detection means using a voltage detection method. The lithium ion secondary battery of the present invention is related to Goals 3, 7, 11, and 12 of the SDGs. The lithium ion secondary battery of the present invention includes a solid electrolyte, and a first negative electrode active material which is a spinel type Li4-a-cTi5-bMa+b1O12−δ(M1 is at least one element selected from the group consisting of Li, Na, K, Mg, Ca, Al Zn and transition metal elements, −1≤a≤0.5, 0≤b≤0.5, 0≤c≤0.5, −0.2≤δ≤1) and a specific second negative electrode active material. When the total amount of the first negative electrode active material and the second negative electrode active material contained in the negative electrode is 100% by volume, the proportion of the second negative electrode active material is 5% by volume or more. This is a characteristic feature.