LNCM Electrode Particle Shape Control for Low-Resistance Batteries
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Solution Overview
Problem
Lithium-ion batteries face challenges in increasing energy density while maintaining low resistance, as high potential usage leads to increased resistance and reduced cycle life due to gas generation and particle cracking, and the spherical shape of conventional LNCM particles results in voids and decreased conductivity.
Innovation Solution
The use of an electrode with an active material-containing layer comprising single particles of a lithium-containing metal oxide with specific molar ratios and elements, optimized for circularity and porosity, which reduces particle cracking and enhances contact between particles, thereby suppressing AC and DC resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If LNCM positive electrode active material is used up to a positive electrode potential as high as 4.2 V or more to increase capacity, then battery capacity increases, but resistance increases significantly due to gas generation and side reactions
Solution Approach 1:
The patent changes the particle shape parameter from spherical (circularity close to 1) to non-spherical shapes with controlled circularity (0.3-0.8), which fundamentally alters the packing behavior and contact characteristics of particles in the positive electrode, thereby resolving the contradiction between capacity and resistance
Solution Approach 2:
The patent uses LNCM composite oxide material with specific composition ratios (Li: 0.95-1.05, Ni: 0.6-0.8, Co: 0.05-0.2, Mn: 0.1-0.3) to achieve both high capacity and suppressed resistance, combining multiple elements to obtain synergistic effects that resolve the capacity-resistance contradiction
2Ease of manufacture
If spherical particles with circularity close to 1 are used, then particle shape is simple and easy to manufacture, but voids increase and positive electrode density does not increase
Solution Approach 1:
The patent deliberately introduces asymmetry in particle shape by controlling circularity to be 0.3-0.8 rather than close to 1, which allows particles to pack more efficiently in the electrode structure, reducing voids and increasing positive electrode density while remaining manufacturable
3Device complexity
If spherical particles with circularity close to 1 are used, then particle shape is simple, but contact between particles becomes point contacts and conductivity decreases
Solution Approach 1:
The patent uses non-spherical particles with controlled circularity (0.3-0.8) that create extended contact areas between particles rather than point contacts, significantly improving conductivity while maintaining reasonable manufacturing complexity
Solution Approach 2:
The patent changes the circularity parameter from close to 1 to 0.3-0.8, which fundamentally transforms the contact geometry between particles from point contacts to face-to-face or edge-to-face contacts, thereby improving conductivity
4Quantity of substance
If polycrystalline LNCM system is used, then material can be synthesized with high capacity, but DC resistance increases due to oxidation reaction and positive electrode film formation at high potential
Solution Approach 1:
The patent optimizes the compositional parameters of the LNCM material (specific ratios of Li, Ni, Co, Mn) and controls particle morphology (circularity 0.3-0.8) to reduce surface reactivity and slow down oxidation reactions, thereby suppressing DC resistance increase while maintaining high capacity
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
This approach effectively maintains low resistance during cycling and calendaring at high potentials, improving battery capacity and cycle stability by ensuring adequate contact and reducing oxidation reactions.
Implementation Method 1
an increase in resistance becomes significant due to, for example, gas generation associated with a side reaction between the electrolytic solution and the surfaces of the positive electrode active material particles
Implementation Method 2
formation of a positive electrode film progresses in a polycrystalline system having a large specific surface area due to an oxidation reaction between a positive electrode and an electrolytic solution
Data Source
AI summary
According to one embodiment, an electrode includes an active material-containing layer including single particles of an active material represented by a following formula (1) and a conductive agent. In a cumulative distribution of circularity of unit particles which include the single particles and the conductive agent, an average circularity at 25% in the cumulative distribution is 0.05 to 0.60, and an average circularity at 90% in the cumulative distribution is 0.3 to 0.85. A porosity of the active material-containing layer is 10% to 25%:LiaNi (1-b-c-d) CObMncMdaO2 (1), where 1 ≤ a ≤ 1.2, 0 ≤ b ≤ 0.4, 0 ≤ c ≤ 0.4, 0 ≤ d ≤ 0.1, and M is one or more elements selected from the group consisting of Fe, Cu, Ti, Mg, Al, W, Y, B, Mo, Nb, Zn, Sn, Zr, Ga, and V.