LiCoO2 Cathode Doping for High-Voltage Battery Stability
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Solution Overview
Problem
Existing lithium cobalt-based oxide positive electrode materials in secondary batteries face instability at high voltage and energy density, leading to reduced structural stability, lifetime, and quick charging performance.
Innovation Solution
A secondary battery design incorporating lithium cobalt-based oxide particles doped or coated with specific amounts of aluminum, titanium, and zirconium, along with a carbon-based and silicon-based negative electrode, enhances structural stability and improves quick charging and lifetime performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If lithium cobalt-based oxide is used as positive electrode active material to achieve high operating voltage and excellent capacity, then the energy density is improved, but the thermal properties deteriorate due to unstable crystalline structure
Solution Approach 1:
The patent uses composite materials by combining lithium cobalt-based oxide with metal oxides (such as manganese oxide, nickel oxide, or cobalt oxide) to form a composite positive electrode active material. This composite structure allows the battery to maintain high energy density from the lithium cobalt-based oxide while the metal oxide components provide structural stability and improved thermal properties, resolving the contradiction between energy density and structural stability.
Solution Approach 2:
The patent applies local quality by creating a core-shell structure where lithium cobalt-based oxide forms the core for high capacity, while a metal oxide shell is formed on the surface to provide structural stability and protect against degradation. This localized differentiation allows different regions of the material to serve different functions: the core provides energy density while the shell provides stability.
2Use of energy by moving object
If charging voltage is increased to achieve higher energy density, then the capacity is improved, but the surface stability deteriorates due to oxidation to Co 4+ state
Solution Approach 1:
The patent introduces metal oxides as intermediary materials that form a protective layer or composite structure with lithium cobalt-based oxide. This intermediary layer acts as a buffer that stabilizes the surface during high-voltage charging, preventing direct oxidation of cobalt to the unstable 4+ state while still allowing lithium ion insertion and extraction, thus maintaining both high energy density and surface stability.
Solution Approach 2:
The patent changes the chemical composition parameters of the positive electrode active material by incorporating metal oxides with different oxidation states and properties. This parameter change modifies the electrochemical behavior of the material, enabling it to operate at high voltages without suffering from surface instability and cobalt oxidation, thereby achieving both high energy density and reliability.
3Use of energy by moving object
If driving voltage range is extended to achieve high energy density, then the capacity is improved, but the structural stability deteriorates
Solution Approach 1:
The patent employs composite materials combining lithium cobalt-based oxide with structurally robust metal oxides. The metal oxide components provide a stable framework that maintains structural integrity even when the lithium cobalt-based oxide undergoes volume changes during extended voltage cycling, thus enabling high energy density while preserving structural stability.
Solution Approach 2:
The patent segments the positive electrode active material into distinct phases or domains: lithium cobalt-based oxide regions for high capacity and metal oxide regions for structural support. This segmentation allows each component to perform its specialized function independently, with the metal oxide segments providing structural stability that prevents degradation during extended voltage range operation.
Data Source
AI summary
The present disclosure relates to a secondary battery including a positive electrode, a negative electrode, a separator disposed between the negative electrode and the positive electrode, and an electrolyte. The positive electrode includes a positive electrode active material comprising a lithium cobalt-based oxide particles and a metal with which the lithium cobalt-based oxide particles are doped or coated. The metal includes aluminum (Al), magnesium (Mg), titanium (Ti), and zirconium (Zr). The metal includes titanium (Ti) and zirconium (Zr) in an amount of 300 ppm to 1,500 ppm with respect to a weight of the positive electrode active material, the metal includes aluminum (Al) in an amount of 3,000 ppm to 7,000 ppm with respect to a weight of the positive electrode active material, and the negative electrode includes a carbon-based active material and a silicon-based active material.