Orthorhombic Titanium Oxide Negative Electrode for High-Energy Batteries
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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 energy density limitations.
Innovation Solution
A composite oxide with an orthorhombic crystal structure, represented by the formula Li2+wNa2−xM1yTi6−zM2zO14+δ, is used as the negative electrode active material, where M1 includes Cs and K, and M2 includes Zr, Sn, V, Nb, Ta, Mo, W, Fe, Co, Mn, and Al, allowing for a range of substitutions and vacancies that enhance lithium insertion and extraction capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If titanium oxide is used as negative electrode active material, then rapid charge-and-discharge performance is improved, but energy density decreases due to higher potential and lower capacity per weight
Solution Approach 1:
The patent changes the crystal structure parameter of titanium oxide from conventional anatase or rutile to a specific orthorhombic structure with space group Pnma, which fundamentally alters the lithium insertion/extraction properties and reduces the potential to below 1.5 V vs. Li/Li+, thereby improving energy density while maintaining rapid charge-and-discharge performance
Solution Approach 2:
The patent creates local structural features within the orthorhombic titanium oxide by controlling particle morphology and size distribution, optimizing the crystal orientation to expose specific crystal planes that facilitate lithium ion transport while maintaining the low potential characteristic
2Quantity of substance
If carbonaceous material is used as negative electrode active material, then energy density is improved, but dendrite precipitation occurs during rapid charge-and-discharge cycles
Solution Approach 1:
The patent replaces the conventional carbonaceous material (graphite) with orthorhombic titanium oxide, which although having lower theoretical capacity, provides superior safety and cycle life by preventing dendrite formation, effectively trading some energy density for reliability and operational safety
Solution Approach 2:
The patent develops composite structures where orthorhombic titanium oxide particles are combined with conductive additives and bonded with specific polymers, creating a composite electrode material that maintains electrical conductivity while preventing dendrite precipitation during rapid charging
3Power
If material with high potential based on metal lithium is used as negative electrode material, then voltage increases, but energy density decreases due to lower capacity per weight
Solution Approach 1:
The patent inverts the conventional approach by selecting a negative electrode material (orthorhombic titanium oxide) with lower potential than conventional materials, which paradoxically increases overall battery energy density by enabling the use of high-voltage positive electrode materials and improving the voltage matching between electrodes
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 solution achieves a higher charge-and-discharge capacity, improved voltage management, and increased energy density, enabling stable and efficient rapid charge-and-discharge cycles while maintaining battery life performance.
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
In order to enable rapid charge-and-discharge, electrons and lithium ions must be able to migrate rapidly between the positive electrode and the negative electrode
Data Source
AI summary
In general, according to one embodiment, there is provided an active material. The active material contains a composite oxide having an orthorhombic crystal structure. The composite oxide is represented by a general formula of Li2+wNa2−xM1yTi6−zM2zO14+δ. In the general formula, the M1 is at least one selected from the group consisting of Cs and K; the M2 is at least one selected from the group consisting of Zr, Sn, V, Nb, Ta, Mo, W, Fe, Co, Mn, and Al; and w is within a range of 0≤w≤4, x is within a range of 0<x<2, 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 −0.5≤δ≤0.5.