Coated High-Nickel Cathode Material for Capacity and Thermal Stability
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Solution Overview
Problem
Lithium-ion secondary batteries face challenges in achieving high energy density and maintaining high-temperature cycling and storage performance due to issues with positive electrode active materials.
Innovation Solution
A positive electrode active material is developed with bulk particles containing nickel and a doping element M1, coated with an oxide of element M2, where the average valence of M1 increases with delithiation, providing improved capacity extractability and structural stability, while the oxide coating reduces electrolyte corrosion and gas generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If high-nickel positive electrode active material is used to improve energy density, then capacity extractability increases, but structural stability deteriorates and oxidation activity increases
Solution Approach 1:
The patent applies different modifications to different regions of the positive electrode active material: doping element M1 is incorporated into the bulk crystal structure to provide structural stability, while element M2 is applied as a surface coating to reduce oxidation activity. This local differentiation allows the material to achieve both high capacity extractability and improved reliability.
Solution Approach 2:
The patent creates a composite structure by combining nickel-containing lithium composite oxide with doping elements M1 and surface coating element M2. This composite approach integrates multiple functional components: the nickel-based bulk provides high capacity, the doped M1 elements stabilize the crystal structure, and the M2 coating layer suppresses surface oxidation, collectively resolving the contradiction between capacity and stability.
2Quantity of substance
If high-nickel positive electrode active material is used to improve energy density, then capacity extractability increases, but oxidation activity increases leading to gas generation
Solution Approach 1:
The patent introduces element M2 as an intermediary substance that forms a protective coating layer on the surface of the positive electrode active material. This coating layer acts as a barrier between the high-nickel bulk material and the electrolyte, preventing direct contact and reducing oxidation reactions that would otherwise generate gas. The intermediary coating allows the high-capacity nickel material to function while suppressing harmful oxidation activity.
3Ease of manufacture
If conventional positive electrode active material is used, then manufacturing is simple, but high-temperature cycling performance and storage performance are poor
Solution Approach 1:
The patent modifies the chemical composition parameters of the positive electrode active material by incorporating doping element M1 and surface coating element M2. These parameter changes—specifically the addition of elements with appropriate ionic radii and valences—enhance the material's thermal stability and structural integrity at high temperatures, thereby improving cycling and storage performance while maintaining compatibility with existing manufacturing processes.
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 significantly enhances energy density, high-temperature cycling performance, and storage performance of lithium-ion secondary batteries by improving lithium ion transmission and reducing oxidation activity.
Implementation Method 1
with the delithiation of the positive electrode active material, the average valence of element M1 increases
Implementation Method 2
capacity extractability of the positive electrode active material is greatly improved
Implementation Method 3
oxidation activity in the electrolyte on the surface of the positive electrode active material is greatly reduced
Data Source
AI summary
This application discloses a positive electrode active material, including bulk particles and a coating layer applied on an exterior surface of each of the bulk particles, where the bulk particle includes a lithium composite oxide that contains element nickel and a doping element M1, and the coating layer includes an oxide of element M2. When the positive electrode active material is in a 11% delithiated state, average valences of element M1 and M2 are α1 and β1, respectively; when the positive electrode active material is in a 78% delithiated state, average valences of element M1 and M2 are α2 and β2, respectively; and α2>α1, β1=β2. Element M1 includes one or more of Si, Ti, Cr, Mo, V, Se, Nb, Ru, Rh, Pd, Sb, Te, Ce, and W, and element M2 is selected from one or more of Mg, Al, Ca, Zr, Zn, Y, and B.