Cobalt-Free Lithium Battery Electrolyte for High-Voltage Cycle Stability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Cobalt-free lithium nickel manganese-based oxide positive electrodes in rechargeable lithium batteries experience structural collapse under high-voltage and high-temperature conditions, leading to transition metal elution, increased battery resistance, and reduced cycle-life and output characteristics.
Innovation Solution
Incorporating a non-aqueous organic solvent with less than or equal to 5 wt% ethylene carbonate and a phosphorus-based compound with a trialkylsilyl group as an additive in the electrolyte solution to stabilize the positive electrode, reducing structural collapse and improving battery stability and cycle-life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If cobalt-free lithium nickel manganese-based oxide is used as positive electrode active material to reduce cost and increase energy density, then manufacturing cost is reduced and energy density is improved, but structural collapse occurs under high-voltage and high-temperature conditions leading to transition metal elution and reduced reliability
Solution Approach 1:
A coating layer comprising at least one of a metal oxide or a metal hydroxide is formed on the surface of the positive electrode active material. This coating layer acts as an intermediary barrier between the positive electrode active material and the electrolyte solution, preventing direct harmful interactions while allowing lithium ion diffusion, thereby suppressing structural collapse and transition metal elution under high-voltage and high-temperature conditions
2Use of energy by moving object
If high voltage region is expanded to increase energy density, then energy density is improved, but electrolyte solution oxidation occurs leading to positive electrode performance deterioration
Solution Approach 1:
The coating layer serves as a protective intermediary that prevents direct contact between the electrolyte solution and the positive electrode active material surface. This intermediary layer suppresses electrolyte oxidation reactions even in the high voltage region (4.3V or higher), thereby maintaining positive electrode performance stability while enabling high energy density operation
Solution Approach 2:
The coating layer changes the surface properties of the positive electrode active material, creating a stable interface that can withstand high voltage conditions. By modifying the surface composition and structure through coating with metal oxide or metal hydroxide, the electrode can operate stably at high voltages (4.3V or higher) without electrolyte oxidation
3Productivity
If transition metals are eluted due to structural collapse in high temperature environment, then capacity is reduced and gas generation occurs, but eluted transition metals precipitate on negative electrode surface causing side reactions and increased resistance
Solution Approach 1:
The coating layer acts as a physical barrier that prevents transition metal elution from the positive electrode active material even under high-temperature conditions. By suppressing the direct interaction between the active material and electrolyte solution, the coating layer prevents transition metal dissolution and subsequent precipitation on the negative electrode, thereby maintaining battery capacity and output characteristics over extended cycle-life
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 structural collapse of the positive electrode, enhancing the stability and cycle-life characteristics of rechargeable lithium batteries even under high-voltage and high-temperature conditions, thereby improving overall battery performance.
Implementation Method 1
the additive includes a phosphorus-based compound including a trialkylsilyl group
Implementation Method 2
electrical energy is produced through oxidation and reduction reactions if lithium ions are intercalated/deintercalated from the positive electrode and negative electrode
Implementation Method 3
a positive electrode and a negative electrode including an active material capable of intercalating and deintercalating lithium ions
Data Source
AI summary
Disclosed are a rechargeable lithium battery including a positive electrode including a positive electrode active material; a negative electrode including a negative electrode active material; and an electrolyte solution including a lithium salt, a non-aqueous organic solvent, and an additive, wherein the positive electrode active material includes a cobalt-free lithium nickel manganese-based oxide, the non-aqueous organic solvent includes less than or equal to about 5 wt % of ethylene carbonate based on a total amount of the electrolyte solution, and the additive includes a phosphorus-based compound including a trialkylsilyl group.