Composite Positive Electrode Active Material for High-Voltage Lithium Batteries
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Solution Overview
Problem
Lithium batteries face challenges in maintaining voltage characteristics and lifespan due to the reduction in structural stability of positive electrode active materials during repeated charging and discharging, especially at high voltages.
Innovation Solution
A composite positive electrode active material is developed, comprising a first metal oxide with a layered structure and a second metal oxide with a spinel phase structure, represented by Li2M1(1+a)Mn(3−a)O8, where M1 is selected from specific elements, and the composite is synthesized through a method involving a solution with M1, Mn, and a chelating agent, followed by heat-treatment with lithium carbonate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a positive electrode active material is used to increase battery capacity and voltage, then the battery capacity and voltage characteristics are improved, but the structural stability of the positive electrode active material deteriorates during repeated charging and discharging
Solution Approach 1:
The patent applies composite materials by combining layered metal oxide and spinel metal oxide to create a composite positive electrode active material. The layered metal oxide provides high capacity characteristics while the spinel metal oxide contributes structural stability, resolving the contradiction between improving battery capacity and maintaining structural stability during cycling.
2Power
If the positive electrode active material operates at high voltage to meet functionality demands, then the battery voltage characteristics are improved, but the structural stability of the positive electrode active material deteriorates
Solution Approach 1:
The composite structure combines layered metal oxide (providing high voltage characteristics) with spinel metal oxide (providing structural stability). This allows the positive electrode to operate at high voltages while maintaining structural integrity during repeated charging and discharging cycles.
Solution Approach 2:
The patent applies local quality by assigning different functional roles to different components of the composite material. The layered metal oxide component is optimized for high voltage and capacity, while the spinel metal oxide component is optimized for structural stability, allowing each component to excel at its specific function.
3Ease of manufacture
If the positive electrode active material structure is simplified to ease manufacture, then the manufacturing process is simplified, but the lifespan and voltage characteristics of the battery deteriorate
Solution Approach 1:
The patent applies preliminary action by pre-forming the composite positive electrode active material with the optimal combination of layered and spinel metal oxides before battery assembly. This pre-composite structure ensures both high performance and manufacturing efficiency, as the complex composite material is prepared in advance rather than during battery assembly.
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 positive electrode active material enhances structural stability during high-voltage charging, leading to improved lifespan and reduced voltage decay in lithium batteries, with the average discharge voltage retention of 97.5% to 99.95% after 50 cycles.
Implementation Method 1
adding to the solution a chelating agent and a precipitating agent to form a precipitate
Implementation Method 2
adding to the solution a chelating agent and a precipitating agent to form a precipitate
Implementation Method 3
heat-treating the mixture to prepare the composite positive electrode active material
Data Source
AI summary
A composite positive electrode active material, the positive electrode active material including: a first metal oxide having a layered structure; and a second metal oxide having a spinel structure, wherein second metal oxide is represented by Formula 1, and wherein the first metal oxide and the second metal oxide form a composite:Li2M1(1+a)Mn(3−a)O8 Formula 1wherein, in Formula 1, −1<a<1; and M1 is at least one element selected from Groups 4 to 10, 13, and 14 of the Periodic Table, and wherein M1 is not Mn. Also a positive electrode including the composite positive electrode active material, and a lithium battery including the positive electrode.