Titanium-Oxide Battery Electrode Conductive Network for Cycle Life
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Solution Overview
Problem
Existing nonaqueous electrolyte batteries using monoclinic or orthorhombic titanium-containing oxides as negative electrodes suffer from inferior cycle life due to volume changes during lithium ion insertion and extraction, leading to increased resistance and electrode deterioration.
Innovation Solution
The electrode design incorporates a fibrous first electro-conductive agent and a second electro-conductive agent with a different shape to maintain electrical bridging between active material particles, adhering to the ratio B/A of 0.6 ≤ B/A ≤ 1.5, ensuring stable conductive paths despite volume changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If monoclinic or orthorhombic titanium-containing oxides are used as negative electrode active material, then high capacity can be achieved, but volume changes during lithium ion insertion and extraction occur, leading to increased resistance and inferior cycle life
Solution Approach 1:
The electrode is segmented into multiple functional components: active material particles (monoclinic or orthorhombic titanium-containing oxides), fibrous electroconductive agent, and non-fibrous electroconductive agent. This segmentation allows each component to perform its specific function - the active material provides high capacity while the dual electroconductive agents work together to maintain conductivity despite volume changes, thereby resolving the contradiction between high capacity and cycle life.
Solution Approach 2:
The invention uses a composite electrode structure combining active material particles with two types of electroconductive agents having different shapes and properties. The fibrous electroconductive agent provides structural framework while the non-fibrous electroconductive agent fills gaps and enhances contact points. This composite approach maintains electrical conductivity during volume changes of the active material, enabling both high capacity and excellent cycle life.
2Device complexity
If only a single electroconductive agent is used in the electrode, then the electrode structure is simpler, but stable electrical bridging between active material particles during volume changes cannot be maintained
Solution Approach 1:
The electrode employs local quality differentiation by using two distinct electroconductive agents with different shapes and properties. The fibrous electroconductive agent provides continuous pathways, while the non-fibrous electroconductive agent creates additional contact points at specific locations. This local differentiation ensures stable electrical bridging throughout the electrode structure during active material volume changes, overcoming the limitations of a single electroconductive agent.
Solution Approach 2:
The invention changes the parameters of the electroconductive system by introducing two electroconductive agents with different shape parameters (fibrous vs. non-fibrous) and different size parameters. The fibrous electroconductive agent has larger dimensions providing structural continuity, while the non-fibrous electroconductive agent has smaller dimensions filling interstitial spaces. This parameter diversification ensures maintained electrical conductivity despite volume changes in the active material.
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
This configuration enhances the cycle life of the battery by maintaining electrical conductivity and preventing electrode deterioration, resulting in improved performance and longevity.
Implementation Method 1
The active material-containing layer contains active material particles, a first electro-conductive agent having a fibrous shape, and a second electro-conductive agent having a shape other than a fibrous shape
Data Source
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AI summary
According to one embodiment, an electrode is provided. The electrode includes an active material-containing layer. The active material-containing layer includes active material particles, a first electro-conductive agent having a fibrous shape, and a second electro-conductive agent having a shape other than the fibrous shape. The active material particles include at least one compound selected from the group consisting of a monoclinic titanium-containing oxide and an orthorhombic titanium-containing composite oxide. The active material-containing layer satisfies formula (1): 0.6 ≤ B/A ≤ 1.5. A is a thickness [µm] of the active material-containing layer. B is a maximum length [µm] of the first electro-conductive agent in the active material-containing layer.