Graphite Negative Electrode with Porous Inorganic Coating
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Solution Overview
Problem
Lithium rechargeable batteries face challenges in achieving high capacity and cycle-life characteristics due to difficulties in lithium ion mobility and electrolyte impregnation in electrodes with high active mass density, particularly when using graphite-based negative active materials.
Innovation Solution
Incorporating inorganic particles such as Al2O3, Ce2O3, or TiO2 on the surface of graphite in the negative electrode, along with a conductive material, to improve electrolyte impregnation and lithium ion transport, resulting in a negative electrode with an active mass density of at least 1.65 g/cc and enhanced rate capability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the active material layer is formed to have greater than or equal to about 30 mg/cm2 of weight per unit area and the negative electrode is compressed to have active mass density of greater than or equal to 1.70 g/cc to realize high capacity, then the capacity increases, but lithium ion mobility becomes difficult and cycle-life characteristics deteriorate
Solution Approach 1:
The invention uses porous inorganic particles (such as Al2O3, TiO2, SiO2) with specific pore structures as coatings on graphite particles. These porous materials create channels and pathways that facilitate electrolyte penetration and lithium ion transport throughout the electrode, even at high compression densities of ≥1.70 g/cc, thereby maintaining good cycle-life characteristics while achieving high capacity
Solution Approach 2:
The invention creates a composite structure by coating inorganic particles on the surface of graphite particles. This composite approach combines the high capacity of graphite with the ion-conducting properties of porous inorganic materials, resolving the contradiction between high capacity and good cycle-life by enabling both high active material loading and efficient lithium ion mobility
2Quantity of substance
If the active material layer is formed to have greater than or equal to about 30 mg/cm2 of weight per unit area to realize high capacity, then the capacity increases, but electrolyte impregnation becomes difficult and power characteristics deteriorate
Solution Approach 1:
The porous inorganic particle coatings provide a three-dimensional network of pores and channels that facilitate rapid electrolyte penetration into the electrode interior. This porous structure maintains excellent electrolyte impregnation even when the active material layer weight per unit area is ≥30 mg/cm2, thereby preserving good power characteristics alongside high capacity
Solution Approach 2:
The inorganic particles act as intermediary structures between the electrolyte and the graphite active material. They provide conductive pathways and facilitate electrolyte distribution throughout the electrode, enabling efficient lithium ion transport and maintaining good power characteristics even at high loading densities
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 approach leads to improved electrolyte impregnation, reduced electric resistance, and superior cycle-life and rate capability of rechargeable lithium batteries by ensuring uniform electrolyte distribution and efficient lithium ion transport.
Implementation Method 1
a positive electrode including a positive active material capable of intercalating/deintercalating lithium ions and a negative electrode including a negative active material capable of intercalating/deintercalating lithium ions
Data Source
AI summary
Provided are a negative electrode for a rechargeable lithium battery including a negative active material and a conductive material wherein the negative active material includes graphite and an inorganic particle positioned on the surface of the graphite and having no reactivity with lithium, and the conductive material is included in an amount of greater than or equal to about 0.1 wt % and less than about 2 wt % based on the total amount of the negative active material and the conductive material, and a rechargeable lithium battery including the same.