Nickel Cathode Surface Film for Cycle Stability and Ion Transport
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Solution Overview
Problem
Conventional secondary batteries face challenges in meeting the increasing demands for improved cycle performance and dynamic performance, particularly in new energy vehicles, due to issues with positive electrode material stability and thermal stability.
Innovation Solution
A composite positive electrode material is developed, comprising a nickel-containing positive electrode material with a functional film layer containing Li2MO4 and a lithium organophosphonate compound, where M is sulfur, selenium, or tellurium, to enhance structural stability, ionic conductivity, and thermal stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a nickel-containing positive electrode material is used to improve capacity, then the energy density is improved, but the structural stability deteriorates leading to particle fracture
Solution Approach 1:
The patent applies composite materials by forming a functional film layer containing both inorganic Li2MO4 and organic lithium organophosphonate compounds on the nickel-containing positive electrode material surface. This composite structure combines the high capacity of nickel-based materials with the protective and stabilizing effects of the functional film, resolving the contradiction between high capacity and structural stability
Solution Approach 2:
The patent uses a thin functional film layer (5-20 nm) as a protective shell on the positive electrode material surface. This thin film maintains structural integrity during charge-discharge cycles while allowing ion transport, preventing particle fracture without significantly blocking ionic conductivity
2Stability of the object's composition
If the functional film layer thickness is increased to improve stability, then the structural stability is improved, but the ionic conductivity deteriorates
Solution Approach 1:
The patent optimizes the thickness parameter of the functional film layer to 5-20 nm, which is thin enough to maintain good ionic conductivity for lithium ion transport, yet thick enough to provide sufficient structural stability and protection. This precise parameter control resolves the contradiction between stability and ionic conductivity
3Device complexity
If conventional positive electrode materials are used to maintain simplicity, then the manufacturing complexity is reduced, but the thermal stability deteriorates
Solution Approach 1:
The patent introduces a functional film layer as an intermediary between the nickel-containing positive electrode material and the electrolyte. This film acts as a thermal barrier and protective interface, improving thermal stability and safety without requiring fundamental changes to the manufacturing process of the underlying electrode material
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 composite material improves cycling stability and dynamic performance by reducing particle fracture and enhancing thermal stability, while maintaining conductive performance.
Implementation Method 1
Li 2 MO 4 and the organic component lithium organophosphonate compound can serve as fast-ionic conductors, effectively enhancing the dynamics performance of the positive electrode material
Implementation Method 2
The specific organic and inorganic components synergistically enhance the strength and stability of the functional film layer, thereby reducing the probability of fracture of positive electrode material particles
Implementation Method 3
the lithium organophosphonate compound exhibits good thermal stability performance and flame-retardant functions, which can enhance the thermal stability of the battery
Data Source
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AI summary
A composite positive electrode material and a preparation method therefor, a positive electrode sheet, a battery, and an electrical apparatus. The composite positive electrode material comprises a nickel-containing positive electrode material and a functional film layer arranged on the surface of the nickel-containing positive electrode material. Components of the functional film layer comprise Li2MO4 and an organic lithium phosphonate compound, where M is selected from at least one of sulfur, selenium, and tellurium; and the organic lithium phosphonate compound contains a structure represented by formula (1): (I), where * represents sites where the structure represented by formula (1) is connected to other structures in the organic lithium phosphonate compound.