Lithium Battery Positive Electrode Material Low-Temperature Resistance
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Solution Overview
Problem
Lithium secondary batteries using conventional lithium metal composite oxides as positive electrode active materials are unsatisfactory for high-output power applications, especially below freezing temperatures, and fail to meet the requirements for automotive and power tool applications.
Innovation Solution
A positive electrode active material with a layered structure represented by the formula LiaM1sM21-sO2, containing nickel, cobalt, and manganese, with specific particle size, crystallite size, pore distribution, and BET specific surface area characteristics, is developed to enhance battery performance and reduce resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If conventional lithium metal composite oxide is used as positive electrode active material, then battery structure is simple and manufacturing is easy, but battery resistance is high below freezing point and power output is insufficient
Solution Approach 1:
The patent changes the particle size parameters of the lithium metal composite oxide, specifically controlling primary particle size to 0.1-1 μm and secondary particle size to 1-10 μm. This parameter optimization improves both power output and reduces battery resistance at low temperatures by enhancing electrolyte penetration and lithium ion diffusion efficiency.
Solution Approach 2:
The patent introduces a porous structure with controlled pore volume (0.01-0.05 cm³/g) and pore size distribution (peak at 10-200 nm) into the lithium metal composite oxide. This porous morphology increases the contact area with electrolyte and facilitates lithium ion transport, thereby improving power output and reducing resistance especially at freezing temperatures.
2Productivity
If conventional lithium metal composite oxide is used, then manufacturing process is simple, but battery performance for high current rate applications is unsatisfactory
Solution Approach 1:
The patent segments the lithium metal composite oxide into primary particles (0.1-1 μm) that aggregate to form secondary particles (1-10 μm). This segmentation increases the total surface area and creates a hierarchical structure that enhances high current rate performance while maintaining manufacturability through controlled synthesis processes.
Solution Approach 2:
The patent optimizes crystallite size parameters (100-1200 Å for (003) plane, 100-700 Å for (104) plane) to improve electrical conductivity and lithium ion diffusion kinetics. These parameter changes enable high current rate performance without significantly complicating the manufacturing process.
3Adaptability or versatility
If lithium secondary battery is designed for high power output, then automotive and power tool applications become feasible, but battery resistance increases below freezing point
Solution Approach 1:
The patent optimizes the composition parameters of the lithium metal composite oxide (LiaM1sM21-sO2 where a=0.9-1.2 and s=0.9-1.0) to achieve low resistance at freezing temperatures. This compositional optimization enables the battery to maintain reliability across diverse applications including automotive and power tool uses in cold environments.
Solution Approach 2:
The introduced porous structure with specific pore volume and size distribution enhances electrolyte access to active material at low temperatures, reducing resistance and enabling reliable operation in freezing conditions across various applications.
Data Source
AI summary
Provided is a positive electrode active material which is useful for a lithium secondary battery having a battery resistance lower than that of the conventional positive electrode active material below freezing point. The positive electrode active material for a lithium secondary battery contains at least one element selected from a group consisting of nickel, cobalt and manganese, the positive electrode active material having a layered structure and satisfying all of the following requirements (1) to (3): (1) a primary particle size is 0.1 μm to 1 μm and a secondary particle size is 1 μm to 10 μm; (2) in an X-ray powder diffraction measurement using CuKα radiation, a crystallite size in the peak within 2θ=18.7±1° is 100 Å to 1200 Å and a crystallite size in the peak within 2θ=44.6±1° is 100 Å to 700 Å; and (3) in a pore distribution obtained by a mercury intrusion method, a pore peak exists in a range where the pore size is 10 nm to 200 nm and a pore volume in the said range is 0.01 cm3/g to 0.05 cm3/g.