Cobalt-Free Li Battery Electrolyte for High-Voltage Cathode Stability
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Solution Overview
Problem
Cobalt-free lithium nickel manganese-based oxide positive electrodes in rechargeable lithium batteries experience structural collapse and transition metal elution under high-voltage and high-temperature conditions, leading to capacity reduction, increased battery resistance, and deteriorated cycle-life characteristics.
Innovation Solution
A rechargeable lithium battery design incorporating a layered positive electrode active material with a cobalt-free lithium nickel manganese-based oxide and an electrolyte solution containing a non-aqueous organic solvent with specific additives, such as ethylene carbonate in limited amounts, and a compound represented by Chemical Formula 1, which effectively reduces transition metal elution and structural collapse, enhancing high-voltage and high-temperature characteristics.
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 transition metal elution increases and structural stability deteriorates under high-voltage and high-temperature conditions
Solution Approach 1:
The patent modifies the chemical composition parameters of the positive electrode active material by controlling the ratio of nickel to manganese atoms and introducing dopant elements. This changes the crystal structure parameters and electronic properties, enabling the material to maintain structural stability at high voltages while remaining cobalt-free, thus resolving the contradiction between cost reduction and reliability maintenance
Solution Approach 2:
The patent creates a composite positive electrode active material by combining cobalt-free lithium nickel manganese-based oxide with dopant elements or coating materials. This composite structure prevents transition metal elution and structural collapse under high-voltage conditions, thereby maintaining reliability while keeping the material cobalt-free for cost effectiveness
2Use of energy by moving object
If high-voltage region is used to expand voltage region and increase energy density, then energy density is improved, but electrolyte decomposition increases and positive electrode performance deteriorates
Solution Approach 1:
The patent introduces a coating layer as an intermediary between the positive electrode active material and the electrolyte. This coating layer acts as a protective barrier that prevents direct contact and chemical reaction between the electrolyte and the positive electrode material at high voltages, thereby suppressing electrolyte decomposition while allowing the battery to operate at high voltages for increased energy density
Solution Approach 2:
The patent applies preliminary protective treatment to the positive electrode active material through doping or coating before battery assembly. This preliminary anti-action creates a stable interface that prevents electrolyte decomposition from occurring in the first place during high-voltage operation, thus enabling high energy density without the harmful effects of electrolyte breakdown
3Power
If high-temperature environment is used to improve battery performance, then power output may be increased, but transition metal elution increases and precipitates on negative electrode causing side reactions
Solution Approach 1:
The patent modifies the thermal stability parameters of the positive electrode active material through compositional optimization and doping. These parameter changes raise the temperature threshold for transition metal elution, allowing the battery to operate at higher temperatures for improved power output without experiencing the harmful effects of metal precipitation on the negative electrode
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 improves the battery's high-voltage and high-temperature performance by suppressing structural collapse and electrolyte decomposition, thereby enhancing cycle-life and stability while reducing internal resistance.
Implementation Method 1
an electrolyte solution effectively protecting a positive electrode including the positive electrode active material to reduce transition metal elution under high-voltage and high-temperature conditions and suppress or reduce structural collapse of the positive electrode
Implementation Method 2
reduce transition metal elution under high-voltage and high-temperature conditions
Data Source
AI summary
Disclosed are a rechargeable lithium battery including an electrolyte solution including a non-aqueous organic solvent, a lithium salt, and an additive; a 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 ethylene carbonate in an amount of less than about 5 wt %, and the additive includes a compound represented by Chemical Formula 1, and the positive electrode active material is represented by Chemical Formula 2. Chemical Formula 1 and Chemical Formula 2 are the same as defined in the specification.