Boron-Coated Lithium Composite Oxide for Micro-Crack Resistant Cathodes
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Lithium secondary batteries face challenges with the lifetime and capacity characteristics of nickel-rich positive electrode active materials due to structural instability and micro-crack formation, which reduces battery performance and longevity, especially at high temperatures.
Innovation Solution
A lithium composite oxide with a boron-containing oxide coating layer is developed, which covers the interface between primary particles and the surface of secondary particles, maintaining a specific correlation between the molar ratio of nickel and the full width at half-maximum (FWHM) of XRD peaks, thereby reducing micro-crack formation and enhancing structural stability and capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the nickel content in the positive electrode active material is increased to achieve high discharge capacity, then the capacity characteristic is improved, but structural instability due to Li/Ni cation mixing is triggered causing micro-crack formation and reduced lifetime
Solution Approach 1:
A coating layer comprising a boron-containing oxide is formed on the surface of the lithium composite oxide particles. This coating layer acts as an intermediary between the nickel-rich positive electrode active material and the electrolyte, preventing direct contact and chemical reactions that would otherwise cause structural instability and micro-crack formation. The coating layer maintains structural stability while allowing the high nickel content (60% or more) to provide high discharge capacity.
2Reliability
If the primary particle size is reduced to inhibit micro-crack generation and improve lifetime, then the lifetime characteristic is improved, but the discharge capacity is reduced
Solution Approach 1:
The invention changes the chemical composition parameter by introducing a boron-containing oxide coating layer on the particle surface. This allows the use of larger primary particles (which provide higher discharge capacity) without suffering from micro-crack formation, as the coating layer prevents the structural degradation that would otherwise occur with particle size reduction.
3Quantity of substance
If a nickel-rich positive electrode active material is used to achieve high capacity, then the capacity characteristic is improved, but cation mixing between Li and transition metal occurs causing structural instability and electrolyte depletion
Solution Approach 1:
The boron-containing oxide coating layer serves as a protective intermediary that prevents direct interaction between the nickel-rich positive electrode active material and the electrolyte. This intermediary layer stabilizes the crystal structure by preventing cation mixing between Li and transition metals, while still allowing lithium ion transport for high capacity performance.
4Reliability
If LiCoO2 is used to achieve excellent lifetime characteristics and charge/discharge efficiency, then the reliability is improved, but the cost increases due to limited cobalt resources
Solution Approach 1:
The invention changes the chemical composition by using a nickel-rich lithium composite oxide (Li1-xNixM1yM2zO2) instead of conventional LiCoO2. By optimizing the nickel content to 60% or more and adding a boron-containing oxide coating layer, the invention achieves both high discharge capacity and excellent lifetime characteristics while reducing dependence on expensive cobalt resources.
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 lifetime and capacity characteristics of lithium secondary batteries by reducing micro-crack formation and enhancing lithium ion conductivity, leading to improved discharge capacity and cycle retention.
Implementation Method 1
a boron-containing oxide coating layer which covers an interface between the primary particles and a surface of the secondary particle
Implementation Method 2
lithium ions are intercalated/deintercalated into/from a positive electrode and a negative electrode
Implementation Method 3
full width at half-maximum (FWHM; deg., 2θ) of a (104) peak among XRD peaks defined by the hexagonal lattice with an R-3m space group
Data Source
AI summary
The present invention relates to a lithium composite oxide including a coating layer having a boron-containing oxide and a lithium secondary battery including the same. More particularly, the present invention relates to a lithium composite oxide improved in lifetime and capacity characteristics by inducing a predetermined correlation between the molar ratio of nickel in a lithium composite oxide including a coating layer having a boron-containing oxide and a full width at half-maximum (FWHM; deg., 2θ) of a (104) peak among XRD peaks defined by the hexagonal lattice with an R-3m space group, and a lithium secondary battery including the same.