Phosphorus-Modified Cathode Binder for High-Temperature Capacity Retention
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Solution Overview
Problem
Secondary batteries experience side reactions and capacity degradation when stored at high temperatures due to electrolyte decomposition and metal ion elution from the positive electrode.
Innovation Solution
A positive electrode with a polyvinyl alcohol modified by a phosphorus compound is used, which forms a binder to prevent direct contact between the positive electrode active material and electrolyte, thereby suppressing side reactions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If high operating voltage (around 4.3 V or higher) is used to improve output and energy density, then battery performance is improved, but side reactions such as electrolyte decomposition occur more readily causing deterioration
Solution Approach 1:
A coating layer comprising polyvinyl alcohol modified with a phosphorus compound is introduced as an intermediary between the positive electrode active material and the electrolyte. This coating layer acts as a protective barrier that suppresses side reactions including electrolyte decomposition and metal ion elution, while allowing the battery to operate at high voltages (4.3V or higher) for improved output and energy density.
Solution Approach 2:
The coating layer uses composite material formed by modifying polyvinyl alcohol with phosphorus compounds (such as phosphoric acid, phosphorous acid, or their esters). This composite structure provides both the binding functionality of the polymer and the protective properties of the phosphorus compound, creating a multifunctional coating that addresses both performance and stability requirements.
2Temperature
If the secondary battery is stored in a high-temperature environment, then operational conditions are maintained, but side reactions become apparent causing decrease in discharge capacity
Solution Approach 1:
The coating layer comprising polyvinyl alcohol modified with a phosphorus compound is applied in advance to the positive electrode active material surface before battery assembly and storage. This preliminary protective action creates a stable interface that prevents high-temperature-induced side reactions during storage, thereby maintaining discharge capacity even when the battery is stored in high-temperature environments.
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 modified polyvinyl alcohol effectively reduces side reactions and metal ion elution, maintaining discharge capacity and improving battery performance at high temperatures.
Implementation Method 1
a coating layer which comprises polyvinyl alcohol modified with a phosphorus compound
Implementation Method 2
polyvinyl alcohol modified with a phosphorus compound
Data Source
AI summary
A positive electrode 13 for secondary battery of the present disclosure includes a positive electrode current collector 11 and a positive electrode active material layer 12 supported on the positive electrode current collector 11, where the positive electrode active material layer 12 includes a positive electrode active material and polyvinyl alcohol modified with a phosphorus compound. A method for manufacturing the positive electrode 13 for secondary battery includes: preparing a polymer solution including polyvinyl alcohol, a phosphorus compound, and a solvent; preparing a positive electrode slurry including the polymer solution and the positive electrode active material; and applying the positive electrode slurry to the positive electrode current collector 11 to form the positive electrode active material layer.