Boron-Coated Ni-Rich Lithium Composite Oxide for Cycle Stability
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Solution Overview
Problem
Existing lithium secondary battery positive electrode active materials, such as LiCoO2, LiMnO2, and Ni-rich materials, face issues of high cost, thermal instability, and reduced capacity due to cation mixing, leading to rapid degradation and safety concerns.
Innovation Solution
A lithium composite oxide with a specific atomic ratio of nickel, cobalt, manganese, aluminum, and boron, and a boron-containing coating layer, optimized for surface and gradient distribution, enhances structural stability and electrochemical performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If Ni-rich positive electrode active material is used to increase capacity, then discharge capacity is improved, but structural stability deteriorates due to Li/Ni cation mixing
Solution Approach 1:
The patent applies local quality by creating a surface region with modified composition and structure. The surface region contains a higher concentration of stabilizing elements and exhibits different structural characteristics compared to the interior, providing localized structural stability at the surface where cation mixing occurs most, while preserving the high-capacity Ni-rich composition in the bulk material.
Solution Approach 2:
The patent employs composite materials by combining Ni-rich lithium composite oxide with surface modifications. The surface region acts as a composite structure with enhanced stability, while the interior maintains the high-capacity Ni-rich composition. This composite approach allows simultaneous achievement of high discharge capacity and improved structural stability.
2Quantity of substance
If Li/Ni cation mixing is intensified to achieve high capacity, then discharge capacity increases, but Li by-products generation increases causing gelation and gas generation
Solution Approach 1:
The patent converts the harmful effect of Li by-products into a beneficial outcome by controlling their formation and distribution. The surface region modification prevents excessive Li by-products generation that would otherwise cause gelation and gas generation, while still allowing sufficient Li by-products to form to maintain high discharge capacity through intensive Li/Ni cation mixing in the bulk.
Solution Approach 2:
The patent applies parameter changes by modifying the composition parameters of the surface region. By adjusting the concentrations of stabilizing elements and the structural parameters of the surface region, the patent controls the extent of Li by-products generation, transforming it from a harmful factor into a controllable parameter that balances capacity and stability.
3Quantity of substance
If Li by-products such as LiOH and Li2CO3 are generated, then discharge capacity increases, but gelation occurs during positive electrode paste preparation
Solution Approach 1:
The patent applies local quality by concentrating stabilizing elements in the surface region, which locally suppresses excessive Li by-products generation. This localized approach allows the bulk material to generate sufficient Li by-products for high discharge capacity while the surface region prevents gelation during paste preparation by limiting by-products in the critical surface area that contacts the paste formulation.
4Quantity of substance
If Li2CO3 residual remains after electrode preparation, then discharge capacity is maintained, but cell swelling increases reducing cycles and battery life
Solution Approach 1:
The patent converts the harmful swelling effect of residual Li2CO3 into a beneficial outcome by controlling its distribution and concentration. The surface region modification ensures that Li2CO3 is present in controlled amounts that maintain discharge capacity while preventing excessive accumulation that would cause cell swelling and reduce cycle life. The surface region acts as a buffer that manages Li2CO3 formation.
Solution Approach 2:
The patent applies parameter changes by modifying the composition and structural parameters of the surface region to control Li2CO3 formation. By adjusting these parameters, the patent optimizes the balance between maintaining sufficient Li2CO3 for high discharge capacity and limiting it to prevent cell swelling and extend battery cycle life.
5Ease of manufacture
If conventional methods are used to determine light element content, then manufacturing process is simple, but measurement precision of boron content is insufficient
Solution Approach 1:
The patent introduces X-ray photoelectron spectroscopy (XPS) as an intermediary measurement technique to accurately determine light element content, particularly boron. XPS serves as a mediator between the simple manufacturing process and the need for precise composition control, enabling accurate measurement of boron content without complicating the manufacturing process itself.
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 composite oxide improves the efficiency and lifetime characteristics of lithium secondary batteries by stabilizing the structure and reducing resistance, thereby enhancing discharge efficiency and preventing capacity loss.
Implementation Method 1
a lithium secondary battery storing electrical energy due to a difference in chemical potential when lithium ions are intercalated/deintercalated into/from a positive electrode and a negative electrode
Implementation Method 2
Batteries store electrical power by using materials facilitating an electrochemical reaction at a positive electrode and a negative electrode
Data Source
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AI summary
The present invention relates to a lithium composite oxide capable of improving capacity and lifetime characteristics of a lithium secondary battery and a lithium secondary battery including the same. According to the present invention, since the atomic ratio of boron (B) and nickel (Ni) in the surface region of the lithium composite oxide including primary particles enabling lithium intercalation and deintercalation and secondary particles formed by aggregating the primary particles is in a specific range, the stability of the lithium composite oxide may be improved, and thus it is possible to improve the capacity and lifetime characteristics of the lithium secondary battery using the lithium composite oxide as a positive electrode active material.