Nickel-Rich Cathode Phosphate Coating for Crack-Resistant Cycling
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Solution Overview
Problem
The nickel-rich cathode material in lithium ion batteries experiences particle cracking over long cycles, exposing internal structures and affecting cycle stability and rate performance.
Innovation Solution
A cathode material with a secondary particle composed of primary particles coated with a first and second phosphate compound layer, where the phosphate content is uniformly distributed to enhance structural stability, thermal stability, and rate performance, and a method involving sintering and solvent washing to achieve these coatings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a coating layer is applied to the cathode material surface, then thermal stability and cycling stability are improved, but coating uniformity is difficult to control and production cost increases
Solution Approach 1:
The patent applies preliminary action by forming the first phosphate compound coating layer on primary particles before sintering. This pre-coating prevents particle aggregation during sintering and ensures uniform distribution of phosphate compounds, which subsequently forms a uniform second coating layer on the secondary particle surface, achieving good coating uniformity while improving cycling stability
Solution Approach 2:
The patent implements nested doll by creating a hierarchical coating structure where the first phosphate compound coating layer is nested within the secondary particle structure, and the second phosphate compound coating layer is formed on the outer surface of the secondary particle. This multi-level nested coating approach ensures both coating uniformity and effective protection of the cathode material
2Temperature
If phosphate compound coating is applied to improve thermal stability, then thermal stability is improved, but production cost increases
Solution Approach 1:
The patent merges the coating process with the sintering process by forming the first phosphate compound coating layer on primary particles before sintering. This integration allows the coating and sintering to be performed in a combined process, reducing the number of separate manufacturing steps and lowering production costs while still achieving the desired thermal stability
Solution Approach 2:
The patent applies self-service by utilizing the sintering process itself to form the phosphate compound coating layer. The phosphate compounds are applied to primary particles and then activated during the sintering process to form a protective coating, eliminating the need for separate coating equipment and processes, thereby reducing production costs
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 cathode material exhibits improved lithium ion conductivity, thermal stability, and cycling performance, with reduced battery impedance and surface corrosion, leading to enhanced rate and long cycle performance.
Implementation Method 1
a coating layer including a first coating layer and a second coating layer, where the first coating layer forms on a surface of the primary particle, the second coating layer forms on a surface of the secondary particle, and the first coating layer and the second coating layer both include phosphate compound
Implementation Method 2
a method involving sintering and solvent washing to achieve these coatings
Data Source
AI summary
A cathode material and a method for preparing the same, lithium ion battery provided. The cathode material includes secondary particle which includes a plurality of primary particles, where the primary particle includes an active material having a chemical formula LibNixCoyMzRwO2, where 0.95≤b≤1.10, 0.8≤x<1, 0<y+z+w≤0.2, x+y+z+w=1, 0.0001≤w≤0.003; M is selected from at least one of Mn and Al, R is a metal; Phosphate compound coating layer are uniformly distributed on the surface of the cathode material, including a first coating layer and a second coating layer, where the first coating layer forms on the surface of the primary particle, the second coating layer forms on the surface of the secondary particle. The cathode material of this application can effectively improve the rate performance, thermal and cycling stability of lithium battery, and has the characteristics of low cost and easy large-scale production.