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 rapid charge-and-discharge cycles due to metal lithium dendrite precipitation, leading to heat generation and internal short circuits, while titanium-containing oxide electrodes offer stability but have lower energy density and higher operating potential, making them unsuitable for high-voltage applications.
Innovation Solution
A composite oxide with a monoclinic crystal structure, represented by the formula LiwNa4-xM1yTi6-zM2zO14+δ, is used as the negative electrode active material, which enhances lithium ion insertion and extraction capabilities, maintaining structural stability and adjusting operating potential for improved energy density and voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If carbon-based negative electrode is used, then energy density is improved, but dendrite precipitation occurs during rapid charge-and-discharge leading to heat generation and internal short circuits
Solution Approach 1:
The patent changes the material parameter from carbon-based to titanium-containing oxide, which fundamentally alters the electrochemical properties. This material substitution enables rapid charge-and-discharge capability while preventing dendrite formation, though it initially increases operating potential. The parameter change is later refined through composite material design to address the energy density issue.
Solution Approach 2:
The patent employs composite materials by combining titanium-containing oxide with other materials to create a negative electrode that maintains both the safety benefits of titanium oxide (dendrite prevention) and improved energy density. This composite approach allows the system to achieve rapid charge-and-discharge performance without sacrificing energy storage capacity.
2Reliability
If titanium-containing oxide is used as negative electrode active material, then rapid charge-and-discharge performance and long-term reliability are improved, but energy density decreases due to higher operating potential and lower capacity per weight
Solution Approach 1:
The patent resolves this contradiction by creating composite negative electrode materials that combine titanium-containing oxide with additional components. This composite structure preserves the excellent charge-and-discharge performance and reliability of titanium oxide while compensating for its lower energy density through the synergistic effects of the composite composition.
Solution Approach 2:
The patent applies local quality by creating heterogeneous structures within the negative electrode where different materials are strategically positioned. This allows specific regions to provide rapid ion transport (titanium-containing oxide) while other regions contribute to higher capacity (complementary materials), achieving both reliability and energy density goals.
3Power
If material with high lithium insertion potential is used, then operating voltage decreases, but series number must be increased for high-voltage applications
Solution Approach 1:
The patent changes the operating potential parameter of the negative electrode by using titanium-containing oxide, which has a higher potential than carbon materials. This shifts the overall battery voltage profile, requiring system redesign for high-voltage applications but enabling lower series numbers and simplified battery pack architecture.
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 high charge-and-discharge capacity, high battery voltage, and excellent life characteristics, addressing the limitations of titanium-containing oxide electrodes and improving the performance of nonaqueous electrolyte batteries for high-energy applications.
Implementation Method 1
when a material into which lithium ions are insertion and from which lithium ions are extracted at a high potential based on metal lithium is used as a negative electrode material
Implementation Method 2
The potential of titanium oxide is due to the redox reaction between Ti3+ and Ti4+ when lithium is electrochemically inserted and extracted
Data Source
AI summary
According to one embodiment, there is provided an active material. The active material includes a composite oxide. The composite oxide has a monoclinic crystal structure. The composite oxide is represented by a general formula of LiwNa4-xM1yTi6-zM2zO14+δ. In the general formula, the M1 is at least one element selected from the group consisting of Rb, Cs, K and H; the 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; w is within a range of 0≤w<12; x is within a range of 0<x<4; y is within a range of 0≤y<2; z is within a range of 0<z<6; and δ is within a range of −0.3≤δ≤0.3.