Nb-Modified TiTa2O7 Anode Material for Linear Solid-State Battery Discharge
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Solution Overview
Problem
Existing all solid batteries face challenges such as leakage of electrolytic solutions, difficulty in detecting end-point voltage due to steep discharge curve slopes, and limited capacity and cycle characteristics.
Innovation Solution
A negative electrode active material with a composition formula of TiTa2−xMxO7, where 0.2≤x≤1.0 and M includes at least Nb, is used. This material has a specific discharge curve slope and grain diameter range that facilitates easy detection of remaining battery capacity and end-point voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a general battery discharge curve is used, then the battery can store and release energy, but the discharge curve slope becomes steeper at low remaining capacity, making end-point voltage detection difficult
Solution Approach 1:
The patent modifies the discharge curve characteristics by changing the electrode material composition to TiTa2-xMxO7 with specific x values and M elements, which alters the voltage-soc relationship to achieve a more linear discharge curve that facilitates accurate end-point detection
2Reliability
If oxide-based solid electrolytes are used, then the battery achieves wider potential window and relative stability, but the negative electrode active material must satisfy multiple constraints including low operating potential and small volumetric changes
Solution Approach 1:
The patent changes the chemical composition parameters of the negative electrode material to TiTa2-xMxO7 with controlled x values (0<x≤1.0) and specific M elements, which simultaneously achieves low operating potential, small volumetric changes, and good electrochemical stability required for oxide-based solid electrolyte systems
Solution Approach 2:
The patent creates a composite oxide material TiTa2-xMxO7 by combining Ti, Ta, and M elements in specific ratios, which integrates multiple desirable properties including low potential operation, structural stability, and compatibility with oxide-based solid electrolytes
3Quantity of substance
If the battery operates at low end-point voltage to maximize capacity, then more energy can be stored, but the voltage drops sharply in a short period, making it difficult to detect when charging should be restarted
Solution Approach 1:
The patent modifies the voltage-soc relationship by changing the electrode material to TiTa2-xMxO7, which produces a more linear discharge curve that maintains a steady voltage decline rate, allowing sufficient capacity utilization while enabling timely detection of the end-point voltage
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 negative electrode active material and all solid battery design enhance coulombic efficiency, cycle characteristics, and capacity, while providing a linear discharge curve for easier detection of remaining capacity and end-point voltage.
Implementation Method 1
an oxide-based solid electrolyte layer... which exhibit high ion conductivity by sintering
Implementation Method 2
a second electrode layer that is provided on a second main face of the oxide-based solid electrolyte layer and includes a negative electrode active material
Data Source
AI summary
A negative electrode active material, characterized in that a composition formula of the negative electrode active material is TiTa2−xMxO7, 0.2≤x≤1.0, and M includes at least Nb.