Lithium Metal Oxide Phosphate Cathode Blending
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Solution Overview
Problem
Lithium ion batteries with lithium metal oxide cathodes composed of nickel, manganese, and cobalt suffer from short cycle life, safety issues, and inconsistent performance, particularly at high discharge rates, despite efforts to improve safety and capacity through coatings and dopants.
Innovation Solution
A method involving the blending of lithium metal oxide with lithium metal phosphate, maintaining the integrity of secondary particles through careful mixing and compaction, achieves improved cycle life, safety, and energy capacity retention by optimizing particle sizes and electronic conductive coatings, resulting in a synergistic effect.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If lithium metal oxide cathodes are used to achieve high specific charge capacity, then energy capacity is improved, but cycle life and safety deteriorate
Solution Approach 1:
The patent applies composite materials by combining lithium metal oxide particles with lithium metal phosphate particles to form a cathode mixture. The lithium metal phosphate acts as a stabilizing component that improves cycle life and safety while the lithium metal oxide provides high specific charge capacity. This composite approach resolves the contradiction by integrating materials with complementary properties.
2Use of energy by moving object
If lithium metal oxide cathodes are used to achieve high specific charge capacity, then energy capacity is improved, but safety deteriorates
Solution Approach 1:
The patent uses composite materials by combining lithium metal oxide with lithium metal phosphate. The lithium metal phosphate component provides inherent safety benefits through its stable olivine structure, which prevents thermal runaway and structural degradation, while maintaining the high capacity characteristics of the lithium metal oxide.
3Object-affected harmful factors
If coatings and dopants are applied to improve safety and capacity, then safety is improved, but manufacturing complexity increases
Solution Approach 1:
The patent merges the functions of safety improvement and capacity enhancement into a single material blending step. Instead of applying separate coatings and dopants through multiple processing steps, the invention combines lithium metal oxide and lithium metal phosphate in a mixture, achieving safety improvements through the inherent stability of the phosphate component while simplifying the manufacturing process.
4Duration of action of stationary object
If lithium metal phosphate is blended with lithium metal oxide to improve cycle life, then cycle life is improved, but volumetric energy capacity may deteriorate due to lower true density
Solution Approach 1:
The patent applies parameter changes by carefully controlling the particle size distribution of both lithium metal oxide and lithium metal phosphate components. By optimizing the size parameters and their distribution in the mixture, the invention achieves improved cycle life through the stabilizing effect of lithium metal phosphate while maintaining acceptable volumetric energy capacity through proper particle size management.
Data Source
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AI summary
An improved method of making a cathode for use in a lithium ion battery is comprised of mixing a lithium metal oxide and lithium metal phosphate in a solvent, where both of these are comprised of primary particles that have been agglomerated into secondary particles of particular size and mixing is insufficient to break up the particles of the lithium metal phosphate, coating the mixture of step (A) on to a metal foil and removing the solvent to form the cathode. The lithium metal oxide is also desirably not broken either. The cathode may be one that has lithium metal oxide and a particular lithium metal phosphate wherein the majority of the metal is Mn.