Dual-Coated Ni-Rich Cathode Material for Battery Lifetime Stability
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Solution Overview
Problem
Existing rechargeable lithium batteries face challenges in achieving high energy density and capacity while maintaining efficient lifetime characteristics due to structural instability and side reactions with the electrolyte.
Innovation Solution
A positive electrode active material comprising first and second lithium composite oxide particles with specific coating layers, where the first particles are coated with aluminium and the second particles are coated with cobalt, enhancing structural stability and reducing side reactions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If high-nickel lithium composite oxide is used to increase energy density, then capacity is improved, but structural stability deteriorates leading to lifetime degradation
Solution Approach 1:
The patent applies local quality by differentiating the coating materials based on particle size. Large particles (≥5μm) are coated with aluminum oxide to maintain structural stability, while small particles (<5μm) are coated with cobalt oxide to enhance charge-discharge efficiency. This localized differentiation resolves the contradiction by providing appropriate protective characteristics to each particle size category, allowing high-nickel content for energy density while maintaining overall structural stability through size-specific coating strategies.
2Speed
If particle size is reduced to improve charge-discharge efficiency, then reaction kinetics are enhanced, but structural stability deteriorates
Solution Approach 1:
The patent implements local quality by assigning different coating materials to different particle size ranges. Small particles (<5μm) receive cobalt oxide coating to provide structural reinforcement and prevent degradation during rapid charge-discharge cycles, while large particles (≥5μm) receive aluminum oxide coating for stability. This resolves the contradiction by allowing small particles to achieve fast kinetics while being protected by cobalt oxide, and large particles to provide structural backbone with aluminum oxide coating.
3Ease of manufacture
If cobalt-free lithium composite oxide is used to reduce cost, then manufacturing cost is reduced, but lifetime characteristics deteriorate due to increased side reactions
Solution Approach 1:
The patent employs intermediary substances (aluminum oxide and cobalt oxide coating layers) to mediate between the cobalt-free lithium composite oxide and the electrolyte. These coating layers act as protective intermediaries that prevent direct contact and side reactions between the high-nickel cobalt-free cathode material and the electrolyte, thereby resolving the contradiction by maintaining cost-effectiveness through cobalt exclusion while preserving lifetime characteristics through intermediary protection.
4Device complexity
If uniform coating is applied to all particles, then manufacturing process is simplified, but performance optimization is limited due to ignoring particle size effects
Solution Approach 1:
The patent applies local quality by implementing size-dependent coating strategies where large particles (≥5μm) are coated with aluminum oxide and small particles (<5μm) are coated with cobalt oxide. This differentiated approach optimizes performance by matching coating materials to particle size characteristics, resolving the contradiction between process simplicity and performance optimization through targeted, size-specific coating applications.
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 solution improves the charge-discharge efficiency and extends the lifetime of the battery by suppressing structural collapse and electrolyte interactions, resulting in enhanced performance and stability.
Implementation Method 1
enhancing structural stability and reducing side reactions
Implementation Method 2
reducing side reactions with the electrolyte
Implementation Method 3
suppressing structural collapse and electrolyte interactions
Data Source
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AI summary
Disclosed are positive electrode active materials and rechargeable lithium batteries. The positive electrode active material comprises a first particle that includes a first lithium composite oxide and has a first average particle diameter, and a second particle that includes a second lithium composite oxide and has a second average particle diameter less than the first average particle diameter. The first particle further includes a first coating layer on a surface of the first lithium composite oxide. The second particle further includes a second coating layer on a surface of the second lithium composite oxide. Each of the first and second lithium composite oxides is lithium composite oxide that includes nickel (Ni) and excludes cobalt (Co). The first coating layer includes aluminium (Al). The second coating layer includes cobalt (Co).