Phosphorus-Coated Cathode Particles for Lower Solid-State Battery Resistance
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Solution Overview
Problem
Sulfide solid electrolytes in all-solid-state batteries deteriorate when in direct contact with positive electrode active material particles, leading to increased battery resistance, which conventional phosphate-based coating films fail to adequately address, especially due to the exclusion of impurities like sodium and potassium that could potentially reduce resistivity.
Innovation Solution
A composite particle with a coating film containing sodium and potassium phosphorus compounds is used, where the coating liquid is formulated to ensure a high concentration of these elements, improving the stability and continuity of the coating film, thereby reducing battery resistance by enhancing the coverage rate and minimizing contact between the sulfide solid electrolyte and positive electrode active material particles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional phosphate-based coating film is formed without sodium and potassium, then the coating film provides basic protection against sulfide solid electrolyte deterioration, but the battery resistance remains high due to insufficient coverage and poor film quality
Solution Approach 1:
The patent changes the chemical composition parameters of the coating film by intentionally incorporating sodium and potassium phosphorus compounds alongside conventional phosphate compounds. This parameter change transforms the coating film from a basic protective layer into a high-quality continuous film that significantly reduces battery resistance while maintaining protection against sulfide solid electrolyte deterioration.
Solution Approach 2:
The patent creates a composite coating film material combining multiple phosphorus-containing compounds (phosphate compounds, sodium phosphorus compounds, and potassium phosphorus compounds). This composite material approach produces a coating film with superior properties including high coverage rate and continuity, which effectively reduces battery resistance while providing robust protection.
2Stability of the object's composition
If impurities like sodium and potassium are excluded from the coating liquid, then the coating film composition is controlled and stable, but the coverage rate is insufficient and battery resistance remains high
Solution Approach 1:
The patent inverts the conventional approach by intentionally adding sodium and potassium (typically considered impurities to be excluded) into the coating liquid. This inversion transforms these elements from harmful contaminants into beneficial components that enhance coating film quality, coverage rate, and continuity, thereby reducing battery resistance while maintaining composition stability through controlled formulation.
Solution Approach 2:
The patent modifies the coating liquid composition parameters by incorporating specific concentrations of sodium phosphorus compounds and potassium phosphorus compounds. This parameter change enables the formation of a continuous coating film with high coverage rate, transforming the coating quality from insufficient to excellent while maintaining stable and controlled composition.
3Reliability
If the coating liquid contains high concentration of phosphoric acid compound, then the coating film provides good protection, but the film continuity is poor and coverage rate is insufficient
Solution Approach 1:
The patent formulates a composite coating liquid containing phosphoric acid compounds combined with sodium phosphorus compounds and potassium phosphorus compounds. This composite formulation produces a coating film that simultaneously achieves high protection quality and excellent continuity, resolving the contradiction between protective capability and film uniformity.
Solution Approach 2:
The patent adjusts the compositional parameters of the coating liquid by incorporating specific phosphorus-containing compounds in optimized ratios. This parameter optimization enables the coating film to form continuously and uniformly across the positive electrode active material particle surface, achieving both high protection quality and excellent film continuity.
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 inclusion of sodium and potassium in the coating film reduces battery resistance by forming a high-quality, continuous coating that improves the coverage rate, leading to a decrease in battery resistance and potentially extending the battery's lifespan.
Implementation Method 1
the phosphoric acid compound may be converted into a low molecule substance by, for example, solvolysis or the like
Data Source
AI summary
The composite particle includes a positive electrode active material particle and a coating film. The coating film covers at least a part of a surface of the positive electrode active material particle. The coating film includes a phosphorus compound. The phosphorus compound includes at least one of Na and K and P.