Nickel-Rich Battery Electrolyte Additives for Thermal Stability
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Solution Overview
Problem
Lithium ion batteries with nickel-rich positive electrode materials face issues such as oxidation of the electrolyte, structural changes, transition metal ion dissolution, chemical side-reactions, and poor thermal stability, which deteriorate their electrochemical and safety properties.
Innovation Solution
A lithium ion battery electrolyte comprising a non-aqueous organic solvent, lithium salt, and additives including cyclophosphazene, lithium fluorophosphate, and silane phosphate, silane phosphite, or silane borate compounds, which improve the stability of nickel-rich positive electrode materials by inhibiting oxidative decomposition and enhancing lithium ion transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If nickel-rich positive electrode material is used to improve energy density, then the theoretical specific capacity increases, but the oxidation property strengthens leading to electrolyte decomposition and structural changes
Solution Approach 1:
The patent introduces a fluorinated cyclic carbonate compound as an intermediary substance in the electrolyte that mediates between the nickel-rich positive electrode material and the electrolyte. This compound优先 reacts with the strong oxidation property of the nickel-rich material, forming a protective interface layer that prevents direct contact and decomposition of the main electrolyte, thus resolving the contradiction between high energy density and electrolyte stability
Solution Approach 2:
The patent modifies the chemical composition parameters of the electrolyte by adding fluorinated cyclic carbonate compound at specific concentrations (0.1-5 wt%). This parameter change alters the chemical properties of the electrolyte system, making it more resistant to oxidation from nickel-rich materials while maintaining good ion conductivity, thereby resolving the contradiction between energy density and reliability
2Use of energy by moving object
If nickel-rich positive electrode material is used to improve energy density, then the theoretical specific capacity increases, but transition metal ion dissolution occurs deteriorating electrochemical properties
Solution Approach 1:
The fluorinated cyclic carbonate compound acts as a protective intermediary that forms a stable interface layer between the nickel-rich positive electrode and electrolyte. This layer effectively suppresses the dissolution of transition metal ions (nickel, cobalt) into the electrolyte, preventing degradation of electrochemical properties while maintaining the high capacity benefits of nickel-rich materials
Solution Approach 2:
The patent applies preliminary anti-action by having the fluorinated cyclic carbonate compound react first with the nickel-rich positive electrode material during initial cycles to form a protective film. This preliminary reaction prevents subsequent dissolution of transition metal ions and maintains electrochemical stability throughout battery operation
3Use of energy by moving object
If nickel-rich positive electrode material is used to improve energy density, then the theoretical specific capacity increases, but thermal stability deteriorates
Solution Approach 1:
The fluorinated cyclic carbonate compound serves as a thermal protective intermediary that forms a stable interface layer with better thermal properties than the original electrolyte-material interface. This layer acts as a thermal barrier, reducing heat transfer and improving the overall thermal stability of the battery system while maintaining the high capacity characteristics of nickel-rich materials
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 electrolyte composition significantly enhances the high temperature cycle performance and safety of lithium ion batteries by reducing gas production, improving low-temperature DC resistance, and maintaining battery stability.
Implementation Method 1
The oxygen atoms in the lithium fluorophosphate structure can be complexed with the transition metal elements of nickel-rich positive electrode active material
Implementation Method 2
the cyclophosphazene compound can effectively absorb the trace water in the electrolyte and the trace water produced by the battery at high temperature
Implementation Method 3
the —O—Si-chemical bond in silane phosphate compound, silane phosphite compound and silane borate compound is easily broken and combines with HF in the electrolyte, and changes the content ratio of the inorganic component to the organic component of the SEI film
Data Source
AI summary
The present invention provides a lithium ion battery and an electrolyte thereof. The electrolyte for the lithium ion battery includes a non-aqueous organic solvent, a lithium salt and additives, wherein the additives include additive A cyclophosphazene compound, additive B lithium fluorophosphate compound, and additive C selected from at least one of silane phosphate compound, silane phosphite compound and silane borate compound. Compared with conventional technologies, the nickel-rich positive electrode lithium ion battery using the electrolyte of the present invention has a desirable cyclic capacity retention rate, a desirable storage capacity retention rate and a low gas production at high temperature, and has a low DC internal resistance at low temperature, which can remarkably improve the thermal stability of lithium ion battery.