Composite Anode Structure for Stable All-Solid Secondary Batteries
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Solution Overview
Problem
Lithium batteries with liquid electrolytes are prone to fires and explosions due to short circuits, posing safety risks, especially in automotive applications. All-solid secondary batteries using solid electrolytes offer improved safety but face challenges in volume changes during charging and discharging, affecting cycling performance.
Innovation Solution
The development of an all-solid secondary battery with a composite anode active material that includes a first metal oxide represented by MaOb (0<a≤3 and 0<b<4) and a carbon-based material, where the metal oxide is dispersed within the carbon-based material matrix, enhancing flexibility and uniform distribution, thereby reducing volume changes and irregular electrode reactions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If solid electrolytes are used instead of liquid electrolytes, then safety is improved, but volume changes during charging and discharging occur
Solution Approach 1:
The patent employs a composite anode active material consisting of metal oxide particles (MaOb) dispersed within a carbon-based material matrix. This composite structure allows the carbon matrix to accommodate volume changes during lithium insertion/extraction while the metal oxide provides high capacity, thus resolving the contradiction between safety and volume stability.
2Reliability
If solid electrolytes are used instead of liquid electrolytes, then safety is improved, but cycling performance deteriorates
Solution Approach 1:
The composite anode active material with metal oxide dispersed in carbon-based matrix provides both high capacity and good cycling stability. The carbon matrix ensures structural integrity during repeated charging/discharging cycles, while the metal oxide contributes to high energy density, thus improving cycling performance while maintaining safety.
Solution Approach 2:
The patent creates a heterogeneous structure where metal oxide particles are distributed within the carbon matrix, allowing different regions to perform different functions: the carbon matrix provides structural stability and conductivity, while the metal oxide provides high capacity. This local differentiation resolves the cycling performance issue.
3Quantity of substance
If metal oxide is used as anode active material, then energy density is improved, but volume changes and irregular electrode reactions increase
Solution Approach 1:
The composite structure combines metal oxide (providing high energy density) with carbon-based material (providing structural stability). The carbon matrix acts as a buffer that accommodates volume expansion/contraction of metal oxide during lithium insertion/extraction, preventing irregular electrode reactions while maintaining high capacity.
Data Source
AI summary
Disclosed is an all-solid secondary battery including a cathode layer, an anode layer, and a solid electrolyte layer between the cathode layer and the anode layer, the cathode layer including a cathode current collector and a cathode active material layer on one surface of the cathode current collector, the anode layer including an anode current collector and a first anode active material layer on one surface of the anode current collector, the first anode active material layer including a first anode active material and a second anode active material, and the first anode active material including a first composite anode active material, wherein the first composite anode active material includes a first metal oxide represented by MaOb (0<a≤3 and 0<b<4, wherein if a is 1, 2, or 3, b is not an integer) and a carbon-based material, the first metal oxide is provided within a matrix of the carbon-based material.