Lithium-Rich Metal Oxide Surface Treatment for Faster Li-Ion Deintercalation
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Solution Overview
Problem
Existing lithium-rich metal oxides used in battery cells suffer from high residual lithium content on their surfaces, which impairs the performance of the battery cells by affecting the processing of the positive electrode plate and the deintercalation of lithium ions, leading to decreased charge capacity.
Innovation Solution
A lithium-rich metal oxide with a controlled residual lithium content of ≤0.5 wt% and a lithium-ion diffusion coefficient of ≥1.0×10−15 cm²/s, combined with a compound LizX on the surface to stabilize the oxide and enhance conductivity, is prepared using an ammonium salt treatment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If lithium-rich metal oxide is used as positive electrode material to improve charge capacity, then the charge capacity of battery cell is improved, but residual lithium on surface impairs processing and deintercalation performance
Solution Approach 1:
The patent removes residual lithium from the surface of lithium-rich metal oxide particles through chemical treatment with ammonium salt solution. This extraction process eliminates the harmful residual lithium while preserving the bulk lithium content that provides charge capacity, thereby resolving the contradiction between maintaining high charge capacity and eliminating processing/deintercalation impairments.
Solution Approach 2:
The patent introduces ammonium salt as an intermediary substance to mediate the removal of residual lithium. The ammonium salt solution acts as a chemical mediator that selectively reacts with and removes surface residual lithium without affecting the bulk material properties, thus enabling the separation of harmful surface lithium from beneficial bulk lithium.
2Ease of manufacture
If residual lithium content is reduced to improve processing and deintercalation, then positive electrode plate processing and lithium ion deintercalation are improved, but charge capacity may be affected
Solution Approach 1:
The patent applies local quality modification by treating only the surface region of lithium-rich metal oxide particles with ammonium salt solution. This localized treatment reduces residual lithium specifically at the surface where it causes processing and deintercalation problems, while leaving the bulk material composition unchanged to preserve charge capacity. The surface-specific modification resolves the contradiction between ease of manufacture and charge capacity.
3Ease of operation
If residual lithium content is reduced to improve lithium ion deintercalation, then deintercalation performance is improved, but charge capacity may be compromised
Solution Approach 1:
The patent performs preliminary chemical treatment with ammonium salt solution before battery assembly to remove residual lithium from the surface. This preliminary action eliminates surface lithium that would otherwise hinder subsequent lithium ion deintercalation during battery operation. By addressing the deintercalation barrier in advance, the treatment improves ease of operation during battery cycling without compromising the bulk lithium content that determines charge 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 solution significantly improves the charge capacity of battery cells by reducing the impact of residual lithium on the processing of the positive electrode plate and facilitating the deintercalation of lithium ions, thereby enhancing the overall performance of the battery cell.
Implementation Method 1
mixing the ammonium salt and the lithium-rich metal oxide core, and treating the mixture to obtain the lithium-rich metal oxide
Implementation Method 2
a lithium-ion diffusion coefficient D of the lithium-rich metal oxide satisfies: D≥1.0×10−15 cm2/s, thereby making it convenient to deintercalate the lithium ions from the lithium-rich metal oxide
Data Source
AI summary
A lithium-rich metal oxide and a preparation method thereof, a positive electrode plate, a battery cell, and a battery are described. The lithium-rich metal oxide includes a lithium-rich metal oxide core and residual lithium on a surface of the lithium-rich metal oxide core. Based on 100 wt % as a total mass of the lithium-rich metal oxide, a mass percent k of the residual lithium satisfies: k≤0.5 wt %, and a lithium-ion diffusion coefficient D of the lithium-rich metal oxide satisfies: D≥1.0×10−15 cm2/s. When applied to a battery cell, the lithium-rich metal oxide of this application improves performance of the battery cell.