TiO2 Composite Negative Electrode for Low Voltage Batteries
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Solution Overview
Problem
The operating voltage of power storage devices using NaTi2(PO4)3 or Na3Ti2(PO4)3 as negative-electrode active materials is high, leading to a low operating voltage for the device, and these materials exhibit significant volume changes during charge and discharge cycles, resulting in decreased cycle characteristics.
Innovation Solution
A negative-electrode active material composition containing 1 to 95% TiO2, 5 to 75% P2O5+SiO2+B2O3+Al2O3+R′O, with 10% or more amorphous phase, which enhances alkali ion diffusivity, reduces redox potential, and stabilizes Ti ion volume changes, thereby increasing the operating voltage and cycle stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If NaTi2(PO4)3 or Na3Ti2(PO4)3 is used as negative-electrode active material, then cycle characteristics are improved, but operating voltage of the power storage device becomes small
Solution Approach 1:
The patent changes the chemical composition parameters by introducing P2O5, SiO2, B2O3, Al2O3, and R′O components in specific proportions (P2O5: 10-50%, SiO2: 5-30%, B2O3: 5-20%, Al2O3: 5-20%, R′O: 1-10%) to form a composite negative electrode material that achieves both low operating voltage and good cycle characteristics
Solution Approach 2:
The patent creates a composite material system combining TiO2 with multiple oxide components (P2O5, SiO2, B2O3, Al2O3, R′O) to form a new negative electrode active material that integrates the advantages of different materials: low voltage from TiO2 and good cycle characteristics from the oxide composite structure
2Quantity of substance
If Si or Sn is used as negative-electrode active material, then theoretical capacity is increased, but volume change occurs due to expansion and contraction during insertion/extraction reaction
Solution Approach 1:
The patent changes the material composition by using TiO2-based compounds with specific oxide additions to achieve a material structure that provides sufficient capacity while maintaining volume stability during charge-discharge cycles
Solution Approach 2:
The patent employs a composite material structure where TiO2 is combined with P2O5, SiO2, B2O3, Al2O3, and R′O to create a stable matrix that accommodates volume changes while maintaining structural integrity and preventing material collapse
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 proposed composition decreases the operating voltage of the negative electrode, increases the discharge capacity and voltage of power storage devices, and inhibits the precipitation of undesirable crystals, resulting in improved cycle characteristics and adhesive strength between the electrode and electrolyte.
Implementation Method 1
it has excellent diffusivity of alkali ions, such as lithium ions or sodium ions and, therefore, facilitates insertion and extraction of alkali ions due to charge and discharge
Implementation Method 2
due to expansion and contraction thereof occurring during insertion/extraction reaction of lithium ions or sodium ions
Data Source
AI summary
Provided is a negative-electrode active material for a power storage device that has a low operating potential, can increase the operating voltage of the power storage device, and has excellent cycle characteristics. The negative-electrode active material for a power storage device, the negative-electrode active material containing, in terms of % by mole of oxide, 1 to 95% TiO2 and 5 to 75% P2O5+SiO2+B2O3+Al2O3+R′O (where R′ represents at least one selected from Mg, Ca, Sr, Ba, and Zn) and containing 10% by mass or more amorphous phase.