Lithium Composite Oxide Crystal Structure for Low-Temperature Battery Performance
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Solution Overview
Problem
Lithium ion secondary batteries for vehicles face challenges in maintaining high output characteristics at low temperatures due to insufficient lithium ion diffusion in conventional cathode materials, despite improved electrical conduction networks and composition adjustments.
Innovation Solution
A lithium-containing composite oxide with a specific crystal structure of space group R-3m, characterized by lattice constants of 14.208 to 14.228 Å for the c-axis and satisfying the relation 3a+5.615≤c≤3a+5.655, along with a binder and electrically conductive material, enhances lithium ion diffusibility and low temperature performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If composition of Ni, Co and Mn is adjusted to increase capacity, then capacity increases to 160 mAh/g, but lithium ion diffusion remains insufficient
Solution Approach 1:
The invention changes the crystallographic parameters by controlling the phase composition ratio. This parameter change affects the atomic arrangement and diffusion pathways, enabling high capacity (160 mAh/g) to be achieved while maintaining sufficient lithium ion diffusion through optimal phase ratio control.
Solution Approach 2:
The invention creates local quality differences within the cathode material by having different phases in specific ratios. The hexagonal and rhombohedral phases are distributed in a specific proportion, creating local regions with different properties that collectively achieve both high capacity and good ion diffusion.
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 lithium-containing composite oxide exhibits excellent low temperature characteristics, maintaining high discharge capacity and rate retention, and improving cycle durability while maintaining initial battery performance.
Implementation Method 1
the diffusibility of lithium ions in the primary particles and the low temperature characteristics of the lithium-containing composite oxide are greatly influenced by the crystal structure particularly by the lattice constants of the a-axis and c-axis
Data Source
AI summary
A lithium-containing composite oxide essentially containing Li, Ni, Co and Mn, which has a crystal structure with space group R-3m, with a c-axis lattice constant being from 14.208 to 14.228 Å, and with an a-axis lattice constant and the c-axis lattice constant satisfying the relation of 3a+5.615≤c≤3a+5.655, and of which the integrated intensity ratio (I003/I104) of the (003) peak to the (104) peak in an XRD pattern is from 1.21 to 1.39.