Lithium-Ion Cathode Material Pore Control for Cycle Stability
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Solution Overview
Problem
Ternary materials used as positive electrode materials in lithium ion batteries suffer from poor cycle performance and severe gas production due to side reactions with the electrolyte, leading to particle degradation and reduced battery performance.
Innovation Solution
A positive electrode material with an intrinsic specific surface area and pore size within specific ranges, achieved through a method involving lithiation and programmed calcining of a nickel cobalt manganese active material, which enhances particle strength and resistance to electrolyte erosion, maintaining controlled pore configuration and lithium ion transfer efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If ternary materials are used as positive electrode materials to achieve high specific energy and cell voltage, then battery energy density is improved, but cycle performance deteriorates and gas production increases
Solution Approach 1:
The patent introduces an intermediary protective layer on the surface of the ternary material particles. This layer acts as a mediator that prevents direct contact between the electrolyte and the ternary material, thereby reducing side reactions and improving cycle performance while maintaining high specific energy
Solution Approach 2:
The patent modifies the surface parameters of the ternary material through coating or surface treatment. By changing the surface composition or structure parameters, the material's resistance to electrolyte erosion is enhanced, improving cycle stability without sacrificing the high voltage and energy density characteristics
2Productivity
If ternary materials undergo side reactions with electrolyte during charging, then metal ion dissolution occurs, but particle strength decreases and cracks expand
Solution Approach 1:
The patent applies preliminary protective measures by coating the ternary material particles before they undergo charging cycles. This pre-protection prevents the harmful side reactions from occurring in the first place, maintaining particle strength and preventing crack formation during normal operation
Solution Approach 2:
A protective coating layer serves as an intermediary barrier between the electrolyte and the ternary material particles. This mediator allows lithium ion transport while blocking direct contact that would cause metal ion dissolution and particle degradation
3Productivity
If more surfaces of positive electrode material are exposed to electrolyte, then side reactions increase, but gas production and particle breakage worsen
Solution Approach 1:
The patent applies a thin film coating on the particle surfaces that is flexible enough to accommodate volume changes during charging/discharging while being impermeable to electrolyte. This thin film reduces the effective surface area exposed to electrolyte, minimizing side reactions and gas production
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 results in improved rate performance and cycle stability, with a discharge capacity of up to 223.8mAh/g and capacity retention of 93.6% after 80 cycles, effectively addressing the limitations of ternary materials.
Implementation Method 1
subjecting a precursor of the positive electrode material to lithiating by: mixing the precursor with a lithium source; and subjecting to programmed calcining
Implementation Method 2
subjecting to programmed calcining under an oxygen atmosphere, wherein the programmed calcining comprises: subjecting to a first calcining at 300-500°C to obtain the first calcined product; and subjecting to a second calcining
Implementation Method 3
subjecting to programmed calcining under an oxygen atmosphere
Data Source
Figure 1A~2
AI summary
The present disclosure relates to a positive electrode material for a lithium ion battery and its preparation. The positive electrode material in accordance with the present disclosure has an intrinsic specific surface area of 5-13 m2/g. The positive electrode material in accordance with the present disclosure has an intrinsic specific surface area and an intrinsic pore size within the required ranges. In this regard, the positive electrode material in accordance with the present disclosure has excellent particle strength, excellent Li ion transference ability, and good resistance to electrolyte erosion. When used in lithium batteries, it may impart the batteries with excellent rate performance and cycle performance. The present disclosure also relates to a method for preparing the positive electrode material.