Low-EC Electrolyte for Cobalt-Free Lithium Battery Stability
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Solution Overview
Problem
Rechargeable lithium batteries with cobalt-free lithium nickel manganese-based oxide positive electrodes face challenges in high-voltage and high-temperature environments, where transition metal elution occurs, leading to structural collapse, gas generation, capacity reduction, and increased battery resistance.
Innovation Solution
A rechargeable lithium battery design that combines a positive electrode made of cobalt-free lithium nickel manganese-based oxide with an electrolyte composed of a non-aqueous organic solvent, a lithium salt, and an additive. The electrolyte is specifically formulated to reduce transition metal elution and structural collapse under high-voltage and high-temperature conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the positive electrode includes cobalt-free lithium nickel manganese-based oxide to reduce cost and increase energy density, then manufacturing cost is reduced and energy density is improved, but transition metal elution occurs under high voltage and high temperature conditions
Solution Approach 1:
A coating layer comprising at least one of an oxide, oxyhydroxide, hydroxide, carbonate, or carboxylate of magnesium, aluminum, potassium, calcium, scandium, titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, zinc, gallium, germanium, or indium is applied to the surface of the lithium nickel manganese-based oxide particles. This coating layer acts as an intermediary barrier between the positive electrode active material and the electrolyte, preventing direct harmful interactions while allowing ionic transport, thus suppressing transition metal elution under high voltage and temperature conditions.
2Use of energy by moving object
If the charging upper limit voltage is increased to expand voltage range and improve energy density, then energy density is improved, but oxidization of electrolyte occurs and positive electrode performance deteriorates
Solution Approach 1:
The patent changes the chemical composition parameters of the positive electrode surface by applying a coating layer with specific metal oxides and hydroxides. This surface modification alters the electrochemical stability window, enabling the battery to operate at higher voltages (4.3V to 4.5V) without causing electrolyte oxidization. The coating layer modifies the interface properties to withstand higher potentials while maintaining stability.
3Power
If the positive electrode is used in high temperature environment to improve output characteristics, then output characteristics are improved, but transition metal elution is aggravated and battery resistance increases
Solution Approach 1:
The coating layer is applied in advance to the surface of the lithium nickel manganese-based oxide particles before battery assembly and initial operation. This preliminary protective action prevents transition metal elution from occurring during subsequent high-temperature operation, thereby preventing the formation of resistive deposits on the negative electrode and maintaining low battery resistance throughout the service life.
4Reliability
If the positive electrode structure is stabilized to prevent collapse and reduce transition metal elution, then reliability is improved, but manufacturing complexity increases
Solution Approach 1:
The coating layer is applied as a thin surface layer that maintains porosity and ionic conductivity while providing structural stabilization. The coating process uses conventional ceramic coating techniques that can be integrated into existing manufacturing lines, avoiding the need for complex new equipment or processes while achieving the desired structural stability and elution prevention.
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 battery configuration enhances high-voltage and high-temperature characteristics by effectively protecting the positive electrode, reducing gas generation, and minimizing increases in battery internal resistance, thereby improving cycle-life and output characteristics.
Implementation Method 1
transition metals may be eluted due to structural collapse of the positive electrode
Implementation Method 2
oxidization of an electrolyte in the high voltage range
Implementation Method 3
causing a problem such as gas generation inside a cell
Implementation Method 4
the eluted transition metals are precipitated on the surface of a negative electrode
Data Source
Figure 1
AI summary
A rechargeable lithium battery including an electrolyte including a non-aqueous organic solvent, a lithium salt, and an additive; positive electrode including a positive electrode active material; and a negative electrode including a negative electrode active material, wherein the non-aqueous organic solvent includes less than about 5 wt% of ethylene carbonate based on the total weight of the non-aqueous organic solvent, the positive electrode active material includes a lithium nickel manganese-based oxide, and the additive includes a compound represented by Chemical Formula 1.