Composite Cathode Active Material for Lithium Battery Stability
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Solution Overview
Problem
Nickel-based cathode active materials in lithium batteries undergo side reactions with the electrolyte due to cracking during charging/discharging, leading to performance deterioration and reduced lifespan.
Innovation Solution
A composite cathode active material is developed, comprising a first metal oxide with layered crystalline phases and a second metal oxide with a composite crystalline phase, where the second metal oxide is disposed on the first phase to prevent side reactions and structural instability, formed through a method involving mixing and heat-treating metal oxides with specific compositions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If nickel-based cathode active materials are used to achieve high capacity, then the battery capacity is improved, but cracks are formed during charging/discharging leading to side reactions with electrolyte and performance deterioration
Solution Approach 1:
The patent applies composite materials by combining nickel-based cathode active material with cobalt-based cathode active material to form a composite structure. The cobalt-based material acts as a buffer that suppresses crack formation in the nickel-based material during charging/discharging cycles, thereby preventing side reactions with electrolyte while maintaining high capacity. This composite approach resolves the contradiction by integrating two materials with complementary properties.
Solution Approach 2:
The patent implements beforehand cushioning by introducing a cobalt-based cathode active material that serves as a cushioning phase before cracks can form and propagate in the nickel-based material. This cushioning effect prevents structural degradation and side reactions with electrolyte, thereby maintaining battery performance stability while preserving the high capacity benefits of nickel-based materials.
2Quantity of substance
If nickel-based cathode active materials are used to achieve high capacity, then the battery capacity is improved, but lifespan characteristics deteriorate due to crack formation and side reactions
Solution Approach 1:
The patent uses composite materials comprising nickel-based and cobalt-based cathode active materials. The cobalt-based component provides structural stability and suppresses crack formation during extended cycling, thereby extending battery lifespan while maintaining the high capacity characteristics of the nickel-based material throughout the battery's service life.
Solution Approach 2:
The cobalt-based cathode active material serves as a cushioning phase that prevents crack formation and propagation before they can occur in the nickel-based material during repeated charging/discharging cycles. This beforehand cushioning effect maintains structural integrity over time, thereby extending battery lifespan while preserving high capacity.
3Quantity of substance
If nickel-based cathode active materials are used to achieve high capacity, then the battery capacity is improved, but gas elution occurs leading to performance deterioration
Solution Approach 1:
The patent applies composite materials by combining nickel-based and cobalt-based cathode active materials. The cobalt-based material suppresses gas elution from the nickel-based material by providing a stable crystal structure that prevents the formation of gaseous by-products during electrochemical reactions, thereby maintaining high capacity without gas generation issues.
Solution Approach 2:
The patent converts the potential harm of gas elution into a benefit by using the cobalt-based cathode active material to suppress gas-forming side reactions. The cobalt-based material acts as a protective phase that redirects electrochemical reactions away from gas-generating pathways, thereby eliminating the harmful effect while preserving the high capacity characteristics of the nickel-based material.
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 cathode active material enhances structural stability, reduces gas generation, and maintains high rate characteristics and lifespan of lithium batteries by minimizing side reactions with the electrolyte.
Implementation Method 1
heat-treating the dried mixture to form the composite cathode active material
Data Source
AI summary
A composite cathode active material includes: a first metal oxide including a plurality of layered crystalline phases comprising a first layered crystalline phase and a second layered crystalline phase, wherein the first and second layered crystalline phases have a different compositions than each other, and a second metal oxide different from the first metal oxide and including a composite crystalline phase, that is different from the first metal oxide, wherein the second metal oxide is represented by Formula 1, wherein at least a portion of the second metal oxide is disposed on a first layered crystalline phase of the plurality of layered crystalline phases of the first metal oxide, and wherein the first layer crystalline phase is in a space group of R-3m:LixMyOz Formula 1wherein, in Formula 1, 0≤x≤3, 1≤y≤3, and 2≤z≤8, andM is at least one selected from a Group 4 element to a Group 13 element.