Rechargeable lithium batteries
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Solution Overview
Problem
Nickel-based positive electrode active materials in lithium batteries suffer from degradation reactions and increased resistance due to gas generation and non-uniform reaction rates when used in high-voltage applications, leading to deteriorated battery performance.
Innovation Solution
A rechargeable lithium battery design incorporating a positive electrode with a mixture of secondary and single particles of lithium nickel-based composite oxide, combined with a non-aqueous electrolyte containing a bicyclic sulfate compound to form a stable, conductive film on the electrode surface, reducing gas generation and resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If nickel-based positive electrode active material is utilized in high-voltage battery, then high capacity is secured, but degradation reactions and gas generation occur due to by-products on the positive electrode active material surface
Solution Approach 1:
A coating layer comprising a bicyclic sulfate compound is formed on the surface of the nickel-based positive electrode active material particles. This coating layer acts as an intermediary between the electrode material and the electrolyte, preventing direct harmful interactions while allowing beneficial electrochemical reactions, thereby suppressing degradation reactions and gas generation at high voltage
Solution Approach 2:
The surface chemistry of the positive electrode active material is modified by introducing a bicyclic sulfate compound coating. This changes the surface properties (chemical composition, surface energy, and reactivity) to reduce side reactions with the electrolyte, enabling high-voltage operation without excessive degradation
2Quantity of substance
If particles with different shapes are mixed to compensate for deterioration, then capacity is improved, but gas is generated due to non-uniform reaction rates on particle surfaces
Solution Approach 1:
The patent applies a uniform coating of bicyclic sulfate compound to the surface of all particles regardless of their shape or size. This creates a consistent protective interface at each local particle surface, ensuring uniform reaction conditions and preventing the non-uniform gas generation that occurs when different shaped particles react at different rates
Solution Approach 2:
The positive electrode active material is designed as a composite structure with a nickel-based core and a bicyclic sulfate compound coating layer. This composite structure combines the high capacity of nickel-based materials with the protective properties of the coating, enabling uniform performance across particles of different shapes
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 effectively suppresses side reactions and resistance increase, enhancing the battery's cycle-life characteristics and energy density while maintaining high capacity and stability at high temperatures.
Implementation Method 1
a non-aqueous electrolyte capable of forming (or providing) a stable film with high conductivity on the positive electrode surface
Implementation Method 2
a positive electrode including a first positive electrode active material and a second positive electrode active material... lithium nickel-based composite oxide
Data Source
AI summary
A rechargeable lithium battery including a positive electrode, a negative electrode, a separator, and a non-aqueous electrolyte is provided. The positive electrode includes a first positive electrode active material including lithium nickel-based composite oxide in the form of secondary particles as a plurality of primary particles agglomerated. The positive electrode includes a second positive electrode active material including lithium nickel-based composite oxide in the form of single particles. The non-aqueous electrolyte includes an organic solvent, a lithium salt, and an additive, and the additive includes a bicyclic sulfate compound.