Silicon-Ring Electrolyte Additives for Stable Nickel-Rich Li-Ion Cathodes
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Solution Overview
Problem
Nickel-rich cathode active materials in lithium-ion batteries face challenges in stabilizing the cathode-electrolyte interface over long-term cycling due to parasitic reactions and electrolyte permeation, leading to impedance growth and capacity decay, especially when hydrogen fluoride is formed from water reacting with lithium salts.
Innovation Solution
Incorporating electrolyte additives functionalized with a five-member ring containing a silicon heteroatom, which creates a protective, uniform film on the cathode surface to inhibit electrolyte decomposition, scavenge hydrogen fluoride, and improve interface stability by forming a physical barrier.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If nickel-rich cathode active material is used to achieve high specific capacity, then battery capacity is improved, but cathode-electrolyte interface stability deteriorates due to parasitic reactions and electrolyte permeation
Solution Approach 1:
The silicon-containing additive performs preliminary action by reacting with hydrogen fluoride and water before they can attack the cathode interface, creating a protective film in advance that prevents subsequent parasitic reactions and stabilizes the interface during cycling
Solution Approach 2:
The silicon-containing additive acts as an intermediary substance that mediates between the harmful hydrogen fluoride/water and the cathode interface, scavenging the harmful species and forming a protective barrier that prevents direct contact and damage to the interface
2Ease of manufacture
If conventional electrolyte formulation is used, then electrolyte cost is reduced, but hydrogen fluoride formation increases leading to nickel dissolution and capacity decay
Solution Approach 1:
The silicon-containing additive converts the harmful hydrogen fluoride into beneficial protective species by scavenging HF and forming a stable protective film on the cathode surface, transforming the harmful byproduct of water reaction into a protective element that stabilizes the interface
Solution Approach 2:
The silicon-containing additive serves as an intermediary that intercepts hydrogen fluoride before it can dissolve nickel from the cathode, creating a protective barrier that prevents the harmful interaction while allowing the conventional electrolyte formulation to remain
3Use of energy by moving object
If no protective film is formed on cathode surface, then electrolyte decomposition is faster, but interface stability and capacity retention deteriorate
Solution Approach 1:
The silicon-containing additive performs preliminary action by forming a protective film on the cathode surface before extensive electrolyte decomposition occurs, preventing subsequent parasitic reactions and maintaining capacity retention over extended cycling periods
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 silicon-functionalized additives enhance the stability of the cathode-electrolyte interface, prevent nickel dissolution, and maintain battery capacity by forming a protective film that oxidizes before electrolyte solvents, effectively reducing impedance and capacity decay.
Implementation Method 1
oxidizes before the electrolyte solvents
Implementation Method 2
scavenges hydrogen fluoride and/or water, with hydrogen fluoride quenching preferred
Implementation Method 3
organically create a physical barrier on the cathode surface. The physical barrier is a protective, uniform film that improves the interface stability, inhibits the decomposition of the electrolyte, inhibits the side reactions at the interface
Data Source
AI summary
A lithium-ion battery has anode active material, nickel-based cathode active material, and an electrolyte. The electrolyte has the following formulation: a carbonate-based solvent; LiPF6; vinylene carbonate; and an additive that satisfies the following: less than or equal to nine carbons; at least one unsaturated bond; a predicted oxidation potential Vox of 2.0<Vox<4.5; and a five member ring with a silicon heteroatom.