Porous Olivine Phosphate Cathode Particles for Low-Temperature Batteries
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Solution Overview
Problem
Olivine-type phosphate compounds exhibit low electrical conductivity and poor low-temperature properties due to insufficient electrolyte permeation and ion conduction in secondary particles.
Innovation Solution
The formation of secondary particles with a high proportion of open pores (40% or more) and a specific pore diameter-to-particle diameter ratio (0.10≤d/D≤0.70) enhances liquid retention and ion conduction, improving low-temperature performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If primary particles are arranged very close to each other in secondary particles, then particle density increases, but electrolyte solution permeation becomes insufficient
Solution Approach 1:
The patent introduces a porous structure within secondary particles by controlling the pore diameter to be 0.1 μm or more. This porous structure creates channels that allow electrolyte solution to permeate into the secondary particles even when primary particles are densely packed. The porous material approach maintains high particle density while ensuring sufficient electrolyte penetration for good ion conduction.
2Reliability
If the proportion of open-pore particles is increased to improve liquid retention, then low-temperature properties improve, but manufacturing complexity increases
Solution Approach 1:
The patent applies parameter changes by specifying a concrete pore diameter parameter (0.1 μm or more) that can be controlled during the granulation process. By defining this specific parameter range, the patent enables manufacturers to produce open-pore particles with desired liquid retention properties through parameter optimization rather than complex process changes. This approach improves low-temperature properties while keeping manufacturing relatively simple through parameter control.
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 enhanced liquid retention and ion conduction lead to improved low-temperature properties and output characteristics in batteries.
Implementation Method 1
The shape of the secondary particles (granules) can affect liquid retention properties for retaining electrolyte solution in the electrode
Implementation Method 2
electrolyte solution tends not to permeate into the secondary particle
Data Source
AI summary
A positive electrode active material comprises powder. The powder includes secondary particles. Each of the secondary particles includes primary particles. Each of the primary particles includes an olivine-type phosphate compound. In an SEM image of the powder, a proportion of the secondary particles each having an open pore is 40% or more. For the secondary particles each having an open pore, a relationship of “0.10≤d/D≤0.70” is satisfied. “d” represents a pore diameter of the open pore. “D” represents a maximum Feret diameter of the secondary particle.