Lithium Compound Coating on Li-Ni Oxide for Battery Swelling
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Solution Overview
Problem
Lithium nickel oxide (Li—Ni oxide) batteries face issues with oxygen radical generation and electrolyte decomposition at high temperatures, leading to swelling, which existing methods like pH control cannot effectively mitigate, especially in high voltage and charged states.
Innovation Solution
A positive electrode material is developed with a lithium compound deposited on the surface of lithium-nickel oxide to cover nickel ions, preventing oxygen radical formation and electrolyte decomposition, using a Li-ion conductive compound like lithium phosphate to minimize gas generation and internal resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If Li-Ni oxide is used as positive electrode active material to increase capacity, then battery capacity is improved, but oxygen radicals are generated at high temperature causing electrolyte decomposition and battery swelling
Solution Approach 1:
A lithium compound coating layer is introduced as an intermediary between the Li-Ni oxide and the electrolyte. This coating layer acts as a protective barrier that prevents direct contact and reaction between the nickel-containing oxide and the electrolyte, thereby suppressing oxygen radical generation and electrolyte decomposition while allowing lithium ion transport to maintain capacity.
Solution Approach 2:
The positive electrode material is designed as a composite structure combining Li-Ni oxide core with a lithium compound coating shell. This composite material approach allows the inner Li-Ni oxide to provide high capacity while the outer lithium compound layer provides protection against high-temperature degradation and electrolyte decomposition.
2Object-generated harmful factors
If pH control method is used to suppress gas formation, then gas generation is reduced, but the method is ineffective at high temperature (60°C or higher) in high voltage state
Solution Approach 1:
Instead of controlling pH of the bulk material, the invention changes the approach by controlling the surface chemistry through coating with a lithium compound. This parameter change from bulk pH control to surface coating provides effective protection specifically under high-temperature and high-voltage conditions where pH control fails.
Solution Approach 2:
The lithium compound coating is applied in advance to the Li-Ni oxide surface before battery assembly and operation. This preliminary protective action ensures that the surface is pre-protected against oxygen radical generation and electrolyte decomposition before any harmful reactions can occur during high-temperature charging or storage.
3Object-generated harmful factors
If lithium compound coating is deposited on Li-Ni oxide surface to cover nickel ions, then electrolyte decomposition is suppressed, but internal resistance may increase
Solution Approach 1:
The lithium compound coating is applied as a thin surface layer with specific local properties - it provides protective quality at the surface while maintaining lithium ion conductivity. The coating thickness and composition are controlled to ensure sufficient protection against electrolyte decomposition while minimizing resistance to lithium ion transport.
Solution Approach 2:
The invention optimizes parameters of the lithium compound coating including thickness, composition, and crystalline structure to achieve the right balance between protection and conductivity. By carefully controlling these parameters, the coating suppresses electrolyte decomposition while maintaining acceptable internal resistance for battery performance.
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 effectively suppresses electrolyte decomposition and swelling even at high temperatures, ensuring stable battery performance and reduced internal resistance, suitable for high-energy density applications like electric vehicles.
Implementation Method 1
a lithium compound deposited on a surface of the oxide, the lithium compound covering nickel present on the surface of the oxide
Implementation Method 2
using a Li-ion conductive compound like lithium phosphate to minimize gas generation and internal resistance
Data Source
AI summary
A positive electrode material for non-aqueous electrolyte lithium ion battery (31, 41) of the present invention has an oxide (11) containing lithium and nickel, and a lithium compound (13) which is deposited on a surface of the oxide (11) and covers nickel present on the surface of the oxide (11). By this structure, it is possible to suppress decomposition of an electrolysis solution as much as possible and drastically reduce swelling of the batteries (31, 41).