Sintered Polycrystalline Cathode with Seed Templates
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Solution Overview
Problem
Current lithium batteries face challenges in optimizing the orientation of lithium-based oxide crystal grains within the cathode active material layer, which affects electron mobility and consequently the battery's capacity and rate capability.
Innovation Solution
The use of sintered polycrystalline materials with seed templates of single crystal plates to align crystal grains of lithium-based oxides, such as LixMO2, in a predetermined direction, facilitating electron movement by controlling the acute angle between the crystal planes and the cathode collector layer, thereby improving electrical conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a mixture of active material particles, conductive material, and binder is used as the cathode active material, then the cathode can be manufactured with conventional methods, but the electron mobility and electrical conductivity are insufficient
Solution Approach 1:
The invention changes the fundamental parameter of cathode material structure from a mixed particle composition to a sintered polycrystalline material with controlled crystal grain orientation. By controlling the crystal orientation parameters (specifically aligning the c-axis perpendicular to the cathode collector layer), the electrical conductivity is significantly improved while maintaining manufacturability through the sintering process
Solution Approach 2:
The invention creates a composite structure at the crystal grain level, where each crystal grain consists of a seed template core and a matrix crystal shell. This composite crystal structure enables both high electrical conductivity through the oriented matrix crystal and controlled growth from the seed template, resolving the contradiction between performance and manufacturing complexity
2Speed
If the crystal grains of lithium-based oxide are not oriented in a predetermined direction, then the cathode active material layer can be formed easily, but the electron mobility is limited
Solution Approach 1:
The invention applies preliminary action by introducing seed templates with predetermined crystal orientation before the sintering process. These seed templates serve as nucleation sites that guide the growth of matrix crystals in the desired orientation (c-axis perpendicular to the collector layer), ensuring high electron mobility without requiring complex post-processing alignment steps
Solution Approach 2:
The seed template acts as an intermediary between the sintering process and the final crystal grain orientation. By providing pre-formed crystal nuclei with specific orientation, the seed templates mediate the transformation from random powder mixture to oriented polycrystalline structure, achieving both electron mobility and manufacturing feasibility
3Quantity of substance
If the cathode active material density is increased, then the battery capacity is improved, but the electrical resistance increases
Solution Approach 1:
The invention changes the structural parameter of the cathode material from a loose particle mixture to a dense sintered polycrystalline structure with oriented crystal grains. This structural transformation allows the material to achieve both high density (improving capacity) and high electrical conductivity (through oriented electron transport paths), resolving the contradiction between quantity and 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
This approach enhances the battery's capacity and rate capability by reducing electrical resistance and increasing the density of the cathode active material, leading to improved performance in lithium batteries.
Implementation Method 1
the cathode active material layer includes a sintered polycrystalline material having a plurality of crystal grains of a lithium-based oxide
Data Source
AI summary
A cathode includes a cathode collector layer, and a cathode active material layer on a surface of the cathode collector layer. The cathode active material layer includes a sintered polycrystalline material having a plurality of crystal grains of a lithium-based oxide, and each of the plurality of crystal grains includes a seed template, and a matrix crystal around the seed template, where the seed template is a single crystal and having a shape of a plate.