Lithium Cobalt Composite Oxide Core-Shell Structure for Battery Energy Density
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Solution Overview
Problem
Lithium secondary batteries require improved energy density and lifespan characteristics, particularly for high-temperature applications like electric vehicles, which existing lithium cobalt oxide materials do not adequately address due to limitations in grain size and shape control.
Innovation Solution
A lithium cobalt composite oxide with a polycrystalline structure, represented by Formula LiaCobOc, is synthesized through heat-treating a mixture of cobalt oxide and a lithium precursor at 1000° C to 1200° C, optimizing the ratio and size of primary and secondary particles for enhanced electrochemical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If conventional lithium cobalt oxide is used to achieve high energy density, then voltage and energy density are improved, but grain size and shape control are insufficient leading to reduced lifespan and poor high-rate characteristics
Solution Approach 1:
The patent applies segmentation by creating a composite oxide structure with distinct functional regions: a core region containing lithium cobalt oxide particles with controlled grain sizes (0.5-5 μm), and a shell region containing lithium cobalt oxide particles with different grain sizes (5-20 μm). This segmented structure allows simultaneous optimization of energy density (through high-capacity core particles) and lifespan/high-rate characteristics (through the shell particles that facilitate ion transport), resolving the contradiction between energy density and manufacturing precision.
Solution Approach 2:
The patent employs composite materials by synthesizing a core-shell structured lithium cobalt composite oxide where the core and shell regions have different particle size distributions and morphological characteristics. The core region provides high energy density through optimized grain size control, while the shell region enhances lifespan and rate characteristics through its own particle size distribution. This composite approach allows both contradictory requirements to be satisfied simultaneously.
2Quantity of substance
If lithium cobalt oxide is used for high capacity applications, then energy density is improved, but high-rate charge/discharge characteristics are insufficient
Solution Approach 1:
The patent segments the lithium cobalt oxide into core and shell regions with different particle size characteristics. The core region contains finer particles (0.5-5 μm) that provide high capacity through increased surface area for lithium insertion/extraction, while the shell region contains coarser particles (5-20 μm) that facilitate rapid ion transport during high-rate charge/discharge. This segmentation enables both high capacity and high-rate characteristics to coexist.
Solution Approach 2:
The patent applies local quality by assigning different particle size distributions to different regions of the composite oxide. The core region is optimized for capacity with finer grain sizes, while the shell region is optimized for rate characteristics with coarser grain sizes. This spatial differentiation of properties allows the material to simultaneously achieve high capacity and high-rate performance.
3Duration of action of stationary object
If lithium secondary battery is designed for long-term use in high temperature conditions, then lifespan is improved, but energy density and discharge capacity are reduced
Solution Approach 1:
The patent uses composite materials with a core-shell structure where the core region provides high discharge capacity through optimized grain size (0.5-5 μm) for maximum lithium storage, while the shell region provides enhanced lifespan through its particle size distribution (5-20 μm) that maintains structural stability during long-term cycling, particularly under high-temperature conditions. This composite structure resolves the trade-off between lifespan and discharge capacity.
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 lithium cobalt composite oxide improves energy density and high-rate charge/discharge characteristics, leading to a lithium secondary battery with extended cycle life and capacity retention.
Implementation Method 1
a positive electrode and a negative electrode, a non-aqueous electrolyte, and a separator, the positive electrode including the lithium cobalt composite oxide
Implementation Method 2
heat-treating a mixture of cobalt oxide (Co3O4) and a lithium precursor at a temperature of about 1000° C. to about 1200° C. to obtain the lithium composite oxide
Implementation Method 3
adjusting the pH of a mixture of a cobalt precursor, a precipitating agent, and a chelating agent to be in a range from about 9 to about 12 to perform co-precipitation and obtain cobalt hydroxide as a precipitate
Data Source
AI summary
Provided is a lithium cobalt composite oxide for a lithium secondary battery represented by Formula 1 below and having a polycrystalline state, a method of preparing the same, a positive electrode for a lithium battery including the lithium cobalt composite oxide, and a lithium secondary battery including a positive electrode, which includes the lithium cobalt composite oxide.LiaCobOc Formula 1In Formula 1, a is an integer from 0.9 to 1.1, b is an integer from 0.980 to 1.0000, and c is an integer from 1.9 to 2.1. Also included is a method of manufacture therefor.