High-Nickel Cathode Particle Control for Low-Gassing Storage
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Solution Overview
Problem
Lithium-ion batteries face limitations in energy density due to inherent properties of commonly used positive active materials like lithium iron phosphate and low-nickel ternary materials, which also result in significant gas production and performance degradation, hindering their commercial mass production.
Innovation Solution
A high-nickel ternary material with a specific composition, LixNiyCozMkMepOrAm, is developed with a surface coating layer, controlled particle morphology, and optimized micro powder content to reduce side reactions with the electrolyte, thereby decreasing gas production and improving storage performance without compromising energy density or cycle performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If high-nickel ternary materials are used to improve energy density, then energy density is improved, but side reactions with electrolyte increase causing severe gas production
Solution Approach 1:
A coating layer comprising Li2SiO3 and Li4SiO4 is formed on the surface of the high-nickel ternary material particles. This coating layer acts as an intermediary barrier between the ternary material and the electrolyte, preventing direct contact and reducing side reactions that cause gas production, while allowing the high-nickel material to maintain its high energy density properties
Solution Approach 2:
The invention changes the chemical composition parameters of the coating layer by controlling the silicon content and oxidation state to form a specific mixture of Li2SiO3 and Li4SiO4 phases. This parameter optimization creates a coating with appropriate thickness and composition that effectively suppresses gas production without compromising the high-nickel material's energy density
2Quantity of substance
If nickel content is increased to improve energy density, then energy density is improved, but cycle performance deteriorates due to severe gassing
Solution Approach 1:
The Li2SiO3-Li4SiO4 coating layer serves as a protective intermediary that stabilizes the interface between the high-nickel ternary material and the electrolyte during cycling. This prevents progressive degradation and gas accumulation that would otherwise deteriorate cycle performance, enabling the battery to maintain high energy density over extended cycling
3Object-generated harmful factors
If washing is performed to reduce residual lithium content and decrease gas production, then gas production is reduced, but reversible capacity per gram decreases
Solution Approach 1:
Instead of washing after material synthesis, the invention performs preliminary action by forming the protective Li2SiO3-Li4SiO4 coating layer on the material surface during or after synthesis. This pre-protection approach reduces gas production from the outset without requiring subsequent washing that would remove residual lithium and reduce reversible capacity
Data Source
AI summary
This application provides a positive active material, a positive electrode plate, an electrochemical energy storage apparatus, and an apparatus. The positive active material is LixNiyCozMkMepOrAm or LixNiyCozMkMepOrAm whose surface is provided with a coating layer. The positive active material is secondary particles, and a particle size Dn10 of the positive active material satisfies: 0.5 μm≤Dn10≤3 μm. In this application, particle morphology of the positive active material and the amount of micro powder in the positive active material are properly controlled, to effectively reduce side reactions between the positive active material and an electrolyte, decrease gas production of the electrochemical energy storage apparatus, and improve storage performance of the electrochemical energy storage apparatus without deteriorating energy density, cycle performance and rate performance of the electrochemical energy storage apparatus.