Lithium Titanium Oxide Negative Electrode for High-Rate Battery Performance
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Solution Overview
Problem
Nonaqueous electrolyte batteries face limitations in high-rate characteristics and charge-discharge cycle life due to insufficient mechanical strength and surface area of the negative electrode, leading to reduced battery capacity and reliability, especially in high-temperature environments.
Innovation Solution
A nonaqueous electrolyte battery design featuring a negative electrode with a current collector and active material having a Li insertion potential not lower than 0.2V and an average primary particle diameter not larger than 1 μm, and a specific surface area of 3 to 50 m2/g, utilizing lithium titanium oxide or titanium-containing composite oxides to enhance lithium ion insertion and release, while maintaining appropriate porosity and mechanical strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the negative electrode is made thinner to increase the density of the negative electrode, then the battery capacity is restricted, but the mechanical strength is insufficient
Solution Approach 1:
The patent employs a composite current collector structure consisting of a support current collector (aluminum or aluminum alloy) and a porous current collector layer (metal foam or porous metal). This composite structure provides both the mechanical strength needed to support thin electrode design and the surface area required for high battery capacity, resolving the contradiction between thickness reduction and structural integrity.
2Strength
If the particle diameter of the active material is increased to maintain mechanical strength, then the interface resistance is increased, but the high-rate performance deteriorates
Solution Approach 1:
The patent applies different particle size specifications to different functional requirements: fine particles (3 μm or less, preferably 1 μm or less) are used to minimize interface resistance and enhance high-rate performance, while the porous current collector structure provides the necessary mechanical strength. This local differentiation of particle quality resolves the contradiction between strength and productivity.
3Productivity
If the specific surface area is increased to improve affinity with electrolyte, then the charge-discharge cycle life is shortened, but the high-rate characteristics improve
Solution Approach 1:
The patent optimizes the specific surface area parameter to fall within 3 to 50 m²/g (preferably 5 to 30 m²/g). This parameter optimization balances the competing requirements: sufficient surface area for good electrolyte affinity and high-rate characteristics, while avoiding excessive surface area that would accelerate degradation and shorten cycle life.
4Reliability
If a nonvolatile and incombustible electrolysis solution is used to improve safety, then the high-rate characteristics and long life performance are reduced
Solution Approach 1:
The patent modifies the electrolyte composition parameters by using a specific mixture of cyclic carbonate (15-40 vol%), chain carbonate (40-70 vol%), and cyclic carboxylate (10-50 vol%). This compositional optimization achieves a balance between safety (using nonvolatile and incombustible components) and performance (maintaining high-rate characteristics through appropriate ionic conductivity).
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 improved battery exhibits enhanced high-rate characteristics and charge-discharge cycle performance, increased battery capacity, and thermal stability, with the specific surface area and particle size optimization preventing agglomeration and ensuring efficient electrolyte affinity.
Implementation Method 1
utilizing lithium titanium oxide or titanium-containing composite oxides to enhance lithium ion insertion and release
Implementation Method 2
a specific surface area of the negative electrode, excluding a weight of the current collector, as determined by the BET method
Data Source
AI summary
A nonaqueous electrolyte battery includes a positive electrode containing an active material, a negative electrode, and a nonaqueous electrolyte, the negative electrode including a current collector and a negative electrode active material supported by the current collector, the negative electrode active material having a Li insertion potential not lower than 0.2V (vs. Li/Li+) and an average primary particle diameter not larger than 1 μm, and a specific surface area of the negative electrode, excluding a weight of the current collector, as determined by the BET method falls within a range of 3 to 50 m2/g.