Spherical P2-Type Cathode Particles With Submicron Crystallites
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Solution Overview
Problem
Positive electrode active materials with a P2-type structure have low reversible capacity.
Innovation Solution
Development of spherical positive electrode active material particles with a P2-type structure comprising transition metal elements like Mn, Ni, and Co, and O, with crystallites less than 1 µm in diameter, and a chemical composition of Na a Mn x-p Ni y-q Co z-r O 2, where 0 < a ≤ 1.00, x + y + z = 1, and 0 ≤ p + q + r ≤ 0.15, produced through a method involving precursor particles coated with a Na salt and fired to achieve a P2-type structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If P2-type structure positive electrode active materials are used, then the battery can operate with sodium ion secondary batteries, but the reversible capacity is low
Solution Approach 1:
The patent applies spheroidality by forming spherical positive electrode active material particles instead of using conventional non-spherical structures. The spherical shape reduces internal stress during sodium ion insertion/extraction cycles, prevents particle cracking, and maintains structural integrity, thereby improving reversible capacity and overall battery performance while retaining the P2-type structure benefits
2Reliability
If the particle surface is covered with crystallites, then the reaction resistance is reduced, but the manufacturing precision requirements increase
Solution Approach 1:
The patent employs parameter changes by controlling the firing temperature (700-900°C) and duration to achieve optimal crystallite formation. By adjusting these thermal parameters, the patent obtains crystallites with diameters of 0.1-1 μm on the spherical particle surface, which reduces reaction resistance while maintaining feasible manufacturing precision through controlled thermal processing
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 spherical particles exhibit high reversible capacity due to reduced reaction resistance and diffusion resistance, improving the performance of sodium ion secondary batteries.
Implementation Method 1
covering the surface of the precursor particle with a Na salt to obtain a covered particle
Implementation Method 2
firing the covered particle to obtain a Na-containing transition metal oxide particle having a P2-type structure
Implementation Method 3
The spherical shape and small crystallite size (less than 1 μm) reduce diffusion resistance, improving reversible capacity
Data Source
Figure 1A~1B
Figure 2
Figure 3~4
AI summary
The reversible capacity of P2-type positive electrode active material particle is increased. A positive electrode active material particle of the present disclosure has a P2-type structure, comprises at least one transition metal elements from among Mn, Ni and Co, with Na and O, as constituent elements, and is spherical.