Lithium-ion Battery Cathode Phosphate Additive Cycle Stability
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Solution Overview
Problem
Lithium-ion secondary batteries face challenges in maintaining long-term cycle characteristics due to degradation issues, particularly with the elution of transition metals from cathode materials, which affects their performance and stability.
Innovation Solution
Incorporating inorganic phosphate particles into the lithium-ion secondary battery, specifically in the cathode, anode, or electrolyte, to suppress the elution of transition metal ions by reacting with them and forming a carbonaceous film on cathode active material particles, thereby enhancing cycle stability and safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If conventional cathode materials are used in lithium-ion secondary batteries, then high voltage and energy density can be achieved, but transition metal ions elute from the cathode during cycling, degrading long-term cycle characteristics
Solution Approach 1:
Inorganic phosphate particles are introduced as intermediary substances that react with eluting transition metal ions to form insoluble compounds. This mediator approach prevents transition metals from reaching and contaminating the anode, thereby maintaining long-term cycle characteristics while preserving high voltage performance
Solution Approach 2:
The eluting transition metal ions, which are harmful to battery performance, are converted into beneficial insoluble phosphate compounds through reaction with inorganic phosphate particles. This transformation eliminates the harmful effect of transition metal elution while maintaining the high voltage characteristics of the cathode material
2Reliability
If inorganic phosphate particles are added to suppress transition metal elution, then long-term cycle characteristics improve, but the device complexity increases
Solution Approach 1:
The particle size of inorganic phosphate is controlled within specific ranges (0.1-10 μm preferably) to optimize both the suppression effect on transition metal elution and the simplicity of manufacturing. By controlling particle size parameters, the invention achieves effective protection without requiring complex processing equipment or multiple material components
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 integration of inorganic phosphate particles significantly improves the long-term cycle characteristics by reducing irreversible capacity and maintaining high discharge capacity retention over 500 cycles, enhancing the stability and safety of lithium-ion secondary batteries.
Implementation Method 1
the battery includes inorganic phosphate particles... suppress the transition metal ions reaching the anode, whereby it is possible to suppress transition metal being eluted from cathode materials
Implementation Method 2
cathode active material particles which include central particles made of LixAyMzPO4... and a carbonaceous film that coats surfaces of the central particles
Data Source
AI summary
A lithium-ion secondary battery including a cathode, an anode, and an electrolyte, in which the lithium-ion secondary battery includes inorganic phosphate particles, and the cathode includes cathode active material particles which include central particles made of LixAyMzPO4 (0≤x≤1.1, 0.8≤y≤1.1, and 0≤z≤0.2; here, A represents at least one element selected from the group consisting of Fe, Mn, Co, and Ni, and M represents at least one element selected from the group consisting of Mg, Ca, Co, Sr, Ba, Ti, Zn, B, Al, Ga, In, Si, Ge, and rare earth elements) and a carbonaceous film that coats surfaces of the central particles.