Pyrophosphate Cathode Composition for High-Voltage Conductive Batteries
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Solution Overview
Problem
There is a need for cathode active materials in all-solid batteries that offer higher voltage and improved electronic conductivity to enhance safety and energy density, as existing phosphate cathode materials with an olivine structure have low voltage and conductivity.
Innovation Solution
A novel cathode active material represented by the compound Lix(Co1−yMy)z(P2O7)4, where 5≤x≤7, 0.01≤y≤0.1, and 4≤z≤6, and M is a Group 3 to 11 element, is developed, which includes doping Co with 4d or 5d metals to increase electronic conductivity and maintain a stable phase, thereby improving high-rate characteristics and energy density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a phosphate cathode material with an olivine structure is used, then the battery structure is stable, but the voltage is low (about 4.8 V) and electronic conductivity is low
Solution Approach 1:
The patent changes the chemical composition parameters by introducing dopant elements M (Group 3-11 elements from 5th and 6th periods) at specific concentration ranges (0.01≤y≤0.1) into the olivine structure. This compositional modification increases electronic conductivity while maintaining the stable olivine framework, resolving the contradiction between structural stability and electrical performance
Solution Approach 2:
The patent creates a composite cathode material Lix(Co1−yMy)z(P2O7)4 that combines the stable olivine phosphate structure with transition metal dopants. This composite approach preserves the structural stability of the host lattice while the dopant elements provide enhanced electronic conductivity and higher operating voltage
2Reliability
If an all-solid battery uses a solid electrolyte instead of flammable organic solvents, then safety is significantly increased, but the driving voltage is lower than carbon-based anode batteries
Solution Approach 1:
The patent develops a cathode material with elevated operating voltage (5≤x≤7 in the formula) specifically tailored for all-solid battery systems. The high voltage capability compensates for the lower driving voltage inherent in solid-state configurations, maintaining overall power performance while preserving the safety benefits of solid electrolytes
3Quantity of substance
If a high-voltage cathode material is used to increase battery energy density, then additional energy density is achieved, but the material requires improved electronic conductivity
Solution Approach 1:
The patent simultaneously optimizes multiple parameters: the stoichiometric ratios (x, y, z) and the selection of dopant elements M are tuned to achieve both high operating voltage (5V or more) and enhanced electronic conductivity. The specific composition ranges ensure high capacity for energy density while the dopants provide necessary electrical conductivity
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 new cathode active material provides a high voltage of 5 volts or more, increased electronic conductivity, and improved high-rate characteristics, leading to enhanced energy density and charge/discharge performance in lithium batteries.
Implementation Method 1
heat-treating the precursor mixture to form the cathode active material
Data Source
AI summary
A cathode active material includes a compound represented by Formula 1:Lix(Co1−yMy)z(P2O7)4 Formula 1wherein in Formula 1, 5≤x≤7, 0.01≤y≤0.1, and 4≤z≤6, and M is a Group 3 to 11 element belonging to 5th and 6th periods in the Periodic Table of the elements, or a combination thereof.