Nonaqueous Electrolyte Cell Composition for Crack-Resistant Deep Discharge
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Solution Overview
Problem
Nonaqueous electrolyte energy storage devices with lithium transition metal composite oxides experience decreased power performance due to crack formation and expansion during deep discharge, leading to increased electrical resistance and performance degradation.
Innovation Solution
Incorporating a lithium transition metal composite oxide with a molar ratio of lithium to transition metals exceeding 1.0, additional elements like aluminum, tungsten, boron, or zinc, and maintaining a negative pressure state within the device to suppress gas generation and electrode expansion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If deep discharge is performed to store sufficient Li in positive active material particles, then energy capacity is improved, but cracks are formed in the particles causing power performance to deteriorate
Solution Approach 1:
The patent applies parameter changes by modifying the Li/Me molar ratio to exceed 1.0 and incorporating additional elements (Al, W, B, Zn, Ti) into the lithium transition metal composite oxide. These compositional parameter changes strengthen the crystal structure to resist crack formation during deep discharge, allowing high Li storage capacity to be maintained while preserving power performance through enhanced structural stability.
2Quantity of substance
If charge-discharge cycles involving deep discharge are performed, then energy density is improved, but electrical resistance increases causing power performance to decrease
Solution Approach 1:
The patent employs composite materials by creating a lithium transition metal composite oxide that integrates multiple elements (Li, Me, and additional elements such as Al, W, B, Zn, or Ti) into a unified crystal structure. This composite structure provides both high Li storage capacity for energy density and enhanced electrical conductivity to maintain low resistance during cycling, resolving the contradiction between energy density and power performance.
3Quantity of substance
If positive active material particles are expanded to store more Li, then energy capacity is improved, but particle structure stability deteriorates leading to crack formation
Solution Approach 1:
The patent applies local quality by strategically incorporating additional elements (Al, W, B, Zn, Ti) into specific positions within the lithium transition metal composite oxide crystal structure. These elements are distributed to provide localized structural reinforcement at critical sites, enabling the particles to accommodate high Li content while maintaining overall structural stability and preventing crack formation.
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 solution effectively reduces power performance degradation by minimizing crack formation and electrode expansion, maintaining optimal electrical resistance and performance over charge-discharge cycles.
Implementation Method 1
a gas soluble in the nonaqueous electrolyte solution is filled inside the case, the inside of the case is in a negative pressure state
Implementation Method 2
the inside of the case is in a negative pressure state, and the electrode assembly is in a state of being pressed in the stacking direction
Data Source
AI summary
The nonaqueous electrolyte energy storage device according to an aspect of the present invention includes an electrode assembly in which a positive electrode containing positive active material particles and a negative electrode are stacked; a nonaqueous electrolyte solution; and a sealable case for housing the electrode assembly and the nonaqueous electrolyte solution, and in the nonaqueous electrolyte energy storage device, the positive active material particles contain a lithium transition metal composite oxide having an α-NaFeO2 structure, the content of lithium element with respect to a transition metal element in the lithium transition metal composite oxide is more than 1.0 in terms of molar ratio, the positive active material particles contain a different kind of element, the different kind of element is aluminum element, tungsten element, boron element, zinc element, titanium element, or a combination of these elements, a gas soluble in the nonaqueous electrolyte solution is filled inside the case, the inside of the case is in a negative pressure state, and the electrode assembly is in a state of being pressed in the stacking direction of the positive electrode and negative electrode.