Li-Ion Positive Electrode Slurry with Low-Moisture Alkali Hydroxide
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Solution Overview
Problem
Lithium-ion batteries face challenges in maintaining low internal resistance and high cycle life, especially at high temperatures, due to limitations in existing positive electrode materials and additives, which affect power performance and capacity retention.
Innovation Solution
A positive electrode slurry composition is developed, incorporating a lithium metal-based oxide, a carbon-based conductivity enhancer, and a binder material, with a powderous alkali hydroxide compound having low water content, which improves dispersion and viscosity, leading to enhanced electrochemical characteristics and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If heavy metal doping (Zr, Nb, Mo, Ta, W) is used to reduce internal resistance, then power performance improves, but cathode energy density decreases and cost increases
Solution Approach 1:
The patent changes the chemical composition parameters by introducing lithium hydroxide (LiOH) as a doping agent with specific stoichiometric ratios (0.01-5 wt% relative to cathode material). This parameter change reduces internal resistance through lithium enrichment and surface modification without introducing heavy metals, thereby maintaining energy density while improving power performance.
Solution Approach 2:
The patent replaces expensive heavy metal dopants (Zr, Nb, Mo, Ta, W) with a cheaper alternative (lithium hydroxide). This substitution maintains the functional benefit of reduced internal resistance while eliminating the cost penalty and energy density loss associated with heavy metal addition.
2Power
If lithium hydroxide is added to reduce internal resistance, then power performance improves, but water content control becomes critical to avoid harmful effects
Solution Approach 1:
The patent precisely controls the water content parameter of lithium hydroxide, specifying it should be less than 5 wt% (preferably less than 1 wt%). This parameter control enables the beneficial effects of LiOH (reduced internal resistance, improved cycle life) while avoiding harmful effects such as gas generation, electrode swelling, and electrolyte decomposition that occur with excessive water content.
Solution Approach 2:
The patent converts the potentially harmful effect of water in lithium hydroxide into a beneficial process by controlling its thermal decomposition. The controlled decomposition of LiOH at elevated temperatures during battery operation or formation cycles releases water vapor that can enrich the electrolyte with lithium ions, improving ionic conductivity while the controlled nature of this process prevents harmful gas accumulation.
3Stability of the object's composition
If high temperature processing is used to decompose lithium hydroxide, then lithium enrichment is achieved, but energy consumption increases
Solution Approach 1:
The patent performs preliminary action by adding lithium hydroxide to the electrode slurry before battery assembly and formation. The LiOH is incorporated into the cathode structure during slurry preparation and drying, positioning it for in-situ decomposition during subsequent formation cycles or initial charging. This eliminates the need for separate high-temperature processing steps, achieving lithium enrichment during normal battery operation rather than through energy-intensive external heating.
Solution Approach 2:
The patent enables self-service by designing the lithium hydroxide decomposition to occur autonomously during battery formation or initial charging cycles. The endothermic decomposition of LiOH absorbs heat from the exothermic lithium insertion reactions occurring during charging, self-regulating the temperature and enabling lithium enrichment without external energy input. The battery's own operational heat drives the decomposition process.
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 results in a positive electrode with low internal resistance, improved cycle life, and better power behavior at both room and elevated temperatures, maintaining high capacity and stability during cycling.
Implementation Method 1
a binder material that is soluble in a polar aprotic solvent
Implementation Method 2
improves dispersion and viscosity
Implementation Method 3
a carbon-based conductivity enhancer
Data Source
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AI summary
A positive electrode slurryfied mixture used in the manufacturing of a rechargeable battery, the mixture comprising: -a positive electrode active material comprising a lithium metal-based oxide, the metal in the lithium metal-based oxide comprising either one or more of Ni, Mn, Al and Co; -a carbon-basedconductivity enhancer; and -a binder material that is soluble in a polar aprotic solvent, characterized in that the mixture further comprises a powderous alkali hydroxyde compound having a water content less than 5wt%.