Layered Cathode Coating for High-Temperature Lithium Battery Stability
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Solution Overview
Problem
Nickel-based active materials used in rechargeable lithium batteries suffer from performance deterioration due to intergranular growth and side reactions with the electrolyte, leading to reduced high temperature life and safety concerns during overcharge.
Innovation Solution
A positive electrode active material is developed, comprising a nickel-based active material with a cobalt-containing coating layer and a boron-containing coating layer, optimized to maintain a specific surface area of 0.45 m2/g to 0.60 m2/g, which enhances high temperature life and suppresses ignition by increasing outgassing during overcharge.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If nickel-based active material is used to increase capacity, then battery capacity is improved, but performance deteriorates due to intergranular growth and side reactions with electrolyte
Solution Approach 1:
A cobalt-containing coating layer is introduced as an intermediary between the nickel-based active material and the electrolyte. This coating layer acts as a protective barrier that prevents direct contact between the nickel material and electrolyte, thereby suppressing side reactions and intergranular growth while maintaining the high capacity benefits of nickel-based materials.
Solution Approach 2:
The invention creates a composite structure by combining nickel-based active material with cobalt-containing coating layer and boron-containing coating layer. This composite material approach allows the system to exhibit both the high capacity characteristics of nickel-based materials and the stability provided by the coating layers, resolving the contradiction between capacity and reliability.
2Quantity of substance
If nickel-based active material is used to increase capacity, then battery capacity is improved, but high temperature life is reduced
Solution Approach 1:
The cobalt-containing coating layer serves as a thermal protective intermediary that shields the nickel-based active material from high temperature degradation. This coating layer remains stable at elevated temperatures and prevents the nickel material from undergoing detrimental changes, thereby extending high temperature life while preserving capacity.
Solution Approach 2:
The composite structure combining nickel-based material with cobalt and boron coating layers provides both high capacity and enhanced thermal stability. The coating layers form a protective framework that maintains structural integrity at high temperatures, allowing the battery to retain its capacity over extended periods under elevated temperature conditions.
3Object-affected harmful factors
If overcharge protection is needed to ensure safety, then ignition risk is reduced, but charge efficiency is compromised
Solution Approach 1:
The boron-containing coating layer is designed to undergo a preliminary protective action during overcharge conditions. When the battery is overcharged to 4.8V or more, this coating layer increases outgassing that activates anti-ignition components, thereby preventing ignition while allowing normal charging operations to proceed with minimal efficiency loss.
Solution Approach 2:
The invention utilizes parameter changes in the coating layer properties under different voltage conditions. During normal charging, the coating layer maintains good ionic conductivity for efficient charging. During overcharge to 4.8V or more, the coating layer undergoes changes that increase outgassing, which activates safety mechanisms without significantly impacting normal charge efficiency.
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 proposed solution significantly improves the high temperature life and charge/discharge efficiency of rechargeable lithium batteries while reducing resistance and suppressing side reactions, thereby enhancing safety by effectively activating anti-ignition components during overcharge.
Implementation Method 1
a cobalt-containing coating layer on a surface of the nickel-based active material; and a boron-containing coating layer on a surface of the cobalt-containing coating layer
Implementation Method 2
the positive electrode active material has a specific surface area of 0.45 m2/g to 0.60 m2/g... suppressing ignition through increase in outgassing amount if overcharged to 4.8 V or more
Data Source
AI summary
A positive electrode active material for rechargeable lithium batteries, a method of preparing the same, and a rechargeable lithium battery including the same are disclosed. The positive electrode active material includes: a nickel-based active material; a cobalt-containing coating layer on a surface of the nickel-based active material; and a boron-containing coating layer on a surface of the cobalt-containing coating layer, wherein the positive electrode active material has a specific surface area of 0.45 m2/g to 0.60 m2/g.