Positive Electrode Plate Composition for Stable Li-Ion Lithiation
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Solution Overview
Problem
Existing lithium-ion secondary batteries face challenges in achieving high energy density, good rate performance, and long cycle life due to issues with irreversible capacity loss during the formation of a solid electrolyte interface (SEI) and instability of lithiation materials, which affect the battery's performance and safety.
Innovation Solution
A positive electrode plate comprising a first positive electrode active material and a second positive electrode lithiation material, with specific resistance, compacted density, and single-sided surface density ratios, along with a designed electrolyte containing vinylene carbonate and 1,3-propane sultone, to enhance stability and lithium ion intercalation, thereby improving energy density and cycle life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a negative electrode lithiation method using lithium metal powder and non-aqueous liquid is used, then energy density is improved, but process complexity and safety hazards increase due to strict moisture control requirements
Solution Approach 1:
The patent introduces a water-based slurry system as an intermediary approach, replacing the problematic non-aqueous liquid lithium metal powder method with a safer water-based lithiation slurry containing lithium compound and conductive carbon, thereby maintaining energy density improvement while eliminating strict moisture control requirements and safety hazards
Solution Approach 2:
The patent changes the chemical composition parameters of the lithiation slurry from non-aqueous lithium metal powder to water-based lithium compounds (such as LiCl, LiBr, LiI) combined with conductive carbon materials, fundamentally altering the system from hazardous to safe while preserving the lithiation function and energy density benefits
2Reliability
If positive electrode lithiation material based on lithium-oxygen compounds is used, then lithiation effect is improved, but battery service life deteriorates due to high decomposition potential and oxygen by-products
Solution Approach 1:
The patent changes the chemical composition of the lithiation material from lithium-oxygen compounds with high decomposition potential to lithium halide compounds (LiCl, LiBr, LiI) combined with conductive carbon, which have lower decomposition potentials and do not produce oxygen by-products, thereby maintaining effective lithiation while extending battery service life
Solution Approach 2:
The patent converts the previously harmful oxygen by-products from lithium-oxygen compound decomposition into beneficial conductive carbon materials that enhance electrical conductivity and structural stability, transforming a harmful effect into a beneficial one while improving both lithiation effect and service life
3Quantity of substance
If Li2NiO2 lithiation material with high free lithium content is used, then lithiation capacity is improved, but processability deteriorates due to slurry gelation and impedance increase
Solution Approach 1:
The patent creates a composite lithiation material system combining lithium halide compounds (LiCl, LiBr, or LiI) with conductive carbon materials in specific ratios, where the conductive carbon component prevents slurry gelation while the lithium halide provides lithiation capacity, thereby maintaining high lithiation capacity while dramatically improving processability and reducing impedance
Solution Approach 2:
The patent optimizes the local composition of the lithiation slurry by controlling the ratio of lithium halide compound to conductive carbon (specifically 95:5 to 50:50 by weight), creating optimal local conditions that prevent gelation while ensuring sufficient lithiation capacity, thereby resolving the contradiction between quantity and processability
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 synergistic effect of the designed positive electrode materials and electrolyte additives results in a lithium-ion secondary battery with high energy density, good rate performance, and extended cycle life, while ensuring process stability and safety.
Implementation Method 1
a designed electrolyte containing vinylene carbonate and 1,3-propane sultone
Implementation Method 2
enhance stability and lithium ion intercalation
Data Source
AI summary
A positive electrode plate includes a positive electrode current collector and a positive electrode active material layer disposed on at least one surface of the positive electrode current collector. The positive electrode active material layer includes a first positive electrode active material Li1+xMnyM2-yO4-tAt and a second positive electrode lithiation material Li1+rMn1-pNpO2-sBs. The positive electrode plate satisfies 1.5≤R·P/Q≤30, where R represents resistance of the positive electrode plate in Ω; P represents compacted density of the positive electrode plate in g/cm3; and Q represents single-sided surface density of the positive electrode plate in g/1540.25 mm2.