Curved Silicon Anode Particles for Battery Cycle Life
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Solution Overview
Problem
Lithium ion secondary batteries face challenges in achieving high capacity due to the saturation of graphite anodes, and the use of silicon anodes results in cycle characteristic degradation due to expansion and shrinkage, leading to stress and peeling of the anode active material layer.
Innovation Solution
An anode with a silicon-based active material layer grown on a current collector using vapor-phase deposition, where primary particles are curved to the collector, reducing stress and enhancing cycle characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If silicon is used as anode active material to increase battery capacity, then battery capacity is improved, but cycle characteristics deteriorate due to expansion and shrinkage causing stress and peeling
Solution Approach 1:
The anode active material layer is formed with a curved surface shape that follows the curvature of the anode current collector. This curved configuration allows the material to expand and shrink during charge-discharge cycles without generating excessive stress, preventing peeling while maintaining high silicon content for improved battery capacity.
Solution Approach 2:
The invention changes the physical parameters of the anode active material layer by controlling its thickness distribution and surface curvature. The layer is designed with varying thickness and curved morphology rather than being uniform and flat, which enables stress relaxation during volume changes of silicon particles during cycling.
2Reliability
If vapor-phase deposition method is used to form anode active material layer, then electron conductivity is improved and miniaturization is inhibited, but stress between current collector and active material layer increases due to expansion and shrinkage
Solution Approach 1:
The vapor-phase deposition process is used to form the anode active material layer with a curved surface configuration that matches the curvature of the anode current collector. This curved structure inherently reduces stress concentration during silicon expansion and shrinkage, preventing delamination while maintaining the excellent electron conductivity achieved through vapor-phase deposition.
3Device complexity
If anode active material layer is grown on current collector, then integration is achieved and miniaturization is inhibited, but shape decay and peeling occur due to repeated charge and discharge stress
Solution Approach 1:
The anode active material layer is formed with a curved surface shape that conforms to the anode current collector's curvature. This curved configuration provides stress relief during repeated charge-discharge cycles, preventing shape decay and peeling of the active material layer while maintaining strong integration between the current collector and active material layer.
Solution Approach 2:
The invention modifies the geometric parameters of the anode active material layer by creating a curved surface with controlled thickness distribution. This parameter change from a flat to a curved structure enables the integrated layer to accommodate volume changes during cycling without losing structural integrity or adhesion to the current collector.
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 curved primary particles alleviate stress and prevent peeling, thereby improving battery cycle characteristics and capacity retention.
Implementation Method 1
forming the anode active material layer on the anode current collector by vapor-phase deposition method
Data Source
AI summary
An anode for a secondary battery capable of improving cycle characteristics, a secondary battery using the anode, and a method of manufacturing an anode for secondary battery. An anode active material layer is formed by vapor phase deposition method, and contains Si as an element. In the anode active material layer, there are a plurality of primary particles grown in the thickness direction. The primary particles aggregate and form a plurality of secondary particles. At least some of the primary particles have shape curved in the identical direction to an anode current collector on the cross section in the thickness direction. Thereby, stress due to expansion and shrinkage due to charge and discharge can be relaxed.