Spirally Twisted Anode Wires for Battery Rate and Stability
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Solution Overview
Problem
Secondary batteries face limitations in shape adaptability and are prone to short circuits due to external impacts, with Si or Sn anode active materials experiencing expansion and shrinkage issues during charging and discharging, and thick anode active material layers hindering lithium ion diffusion.
Innovation Solution
An anode comprising spirally twisted anode wires with an anode active material layer coated on a wire-type current collector, providing a thin layer for efficient lithium ion diffusion and increased surface area, while the twisted structure allows for stress release and improved stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a thick anode active material layer is used to increase battery capacity, then the capacity increases, but lithium ion diffusion becomes difficult and battery performance is restricted
Solution Approach 1:
The anode is divided into multiple wire-type current collectors (e.g., 3-19 wires) with anode active material layers coated on their surfaces. These segmented wires provide numerous thin-layer pathways for lithium ion diffusion, maintaining high capacity while ensuring efficient ion transport throughout the electrode structure.
2Quantity of substance
If Si or Sn is used as anode active material to increase capacity, then the capacity increases, but the active material peels off due to expansion and shrinkage during charging and discharging
Solution Approach 1:
The anode active material is distributed as thin layers on multiple wire-type current collectors rather than a single thick layer. This segmentation reduces the expansion and shrinkage stress on any single material layer, preventing peeling and maintaining electrode integrity during repeated charging cycles.
Solution Approach 2:
The wire-type current collector structure with thin anode active material layers acts as a flexible framework that can accommodate the expansion and shrinkage of Si or Sn materials during lithium insertion and extraction, maintaining structural integrity and preventing material detachment.
3Adaptability or versatility
If a cable-type secondary battery structure is adopted to achieve flexible shapes, then shape adaptability increases, but the battery is frequently subject to external physical impact and twist causing short circuits
Solution Approach 1:
The anode is constructed from multiple independent wire-type current collectors that can move and deform independently. This segmentation allows the battery to absorb external physical impacts and twists without causing short circuits, while maintaining the flexible cable-type shape adaptability.
Solution Approach 2:
The wire-type current collector structure provides dynamic flexibility, allowing the anode to deform and recover from external impacts and twists. This dynamic structure maintains electrical connectivity and prevents short circuits while enabling the battery to adopt various flexible shapes.
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 spirally twisted anode design enhances lithium ion diffusion, improves battery rate characteristics, and increases the battery's life by accommodating expansion and preventing deformation, thus offering better performance and stability.
Implementation Method 1
it is difficult for lithium ions to diffuse in the anode active material layer
Implementation Method 2
anode active material layer which is thin as compared to a single strand anode coated with the same anode active material, to facilitate lithium ion diffusion
Data Source
AI summary
The present invention relates to an anode for a secondary battery, comprising at least two anode wires which are parallel to each other and spirally twisted, each of the anode wires having an anode active material layer coated on the surface of a wire-type current collector; and a secondary battery comprising the anode. The anode of the present invention has an increased surface area to react with Li ions during a charging and discharging process, thereby improving the rate characteristics of a battery, and also release stress or pressure applied in the battery, e.g., the volume expansion of active material layers to prevent the deformation of the battery and ensure the stability thereof, thereby improving the life characteristic of the battery.