Lithium Nickel Oxide Cathode Coating for Battery Safety
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Solution Overview
Problem
Lithium secondary batteries face challenges with low electrical and ionic conductivity, high temperature stability, and safety concerns due to high energy density, which are difficult to address simultaneously, especially in applications like electric vehicles and hybrid electric vehicles.
Innovation Solution
A cathode active material composed of lithium nickel oxide with a nickel content of at least 40% coated with a non-reactive material and carbon, forming a stable interface with the electrolyte to enhance conductivity and prevent excessive discharge and exothermic reactions, thereby improving high temperature stability and rate properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If high energy density is increased to improve battery capacity, then battery capacity is improved, but safety deteriorates due to risks of ignition and explosion
Solution Approach 1:
A coating layer comprising a non-reactive material and a conductive material is applied to the surface of the cathode active material. This coating layer acts as an intermediary between the high-energy cathode material and the electrolyte, preventing direct harmful reactions while maintaining ionic conductivity, thus improving safety without compromising capacity
Solution Approach 2:
The coating layer is formed as a composite structure combining a non-reactive material (such as metal oxide, nitride, or sulfide) with a conductive material (such as carbon material or conductive polymer). This composite structure provides both protective functions (preventing decomposition and exothermic reactions) and conductive functions (maintaining ionic and electrical conductivity), thereby resolving the contradiction between safety and performance
2Power
If conductivity is improved to enhance rate properties, then rate properties are improved, but high temperature stability deteriorates due to increased reactivity
Solution Approach 1:
The coating layer serves as an intermediary barrier that prevents direct contact between the cathode active material and the electrolyte at high temperatures, thereby preventing decomposition reactions and exothermic events while maintaining ionic conductivity through the conductive material component
Solution Approach 2:
The surface of the cathode active material is modified with a coating layer that has different properties from the bulk material. The coating layer provides localized protection against high-temperature reactions while the conductive material within the coating maintains localized ionic conductivity, thus resolving the contradiction between stability and rate properties
Data Source
AI summary
Disclosed herein is a cathode active material based on lithium nickel oxide represented by Formula 1, wherein the lithium nickel oxide has a nickel content of at least 40% among overall transition metals and is coated with a compound not reacting with an electrolyte (“non-reactive material”), which is selected from a group consisting of oxides, nitrides, sulfides and a mixture or combination thereof not reacting with an electrolyte, as well as a carbon material, at a surface of the lithium nickel oxide.