Spirally Wound Battery Electrode Inner End Offset
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current secondary batteries with spirally wound electrode bodies face challenges in maintaining uniform pressure distribution and cycle characteristics due to anode expansion and shrinkage, leading to potential short-circuits and lithium precipitation, which deteriorate load and cycle performance.
Innovation Solution
The design includes a spirally wound electrode body with a cathode and anode active material layers on strip-shaped current collectors, where the inner circumferential end of the cathode active material layer does not overlap with the lead in the short axis direction, and the spirally winding center and outer circumferential ends are positioned to avoid overlap, ensuring uniform pressure distribution and reducing stress concentration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If alloy materials are used as anode active material to achieve high capacity, then the battery energy density is improved, but the anode expansion and shrinkage during charge and discharge cannot be sufficiently suppressed, leading to poor cycle characteristics
Solution Approach 1:
The patent applies local quality by creating a composite anode structure where different materials are distributed in specific regions. The anode contains alloy particles (for high capacity) dispersed within a carbon matrix (for structural stability). This local differentiation allows the alloy to provide high lithium insertion capacity while the carbon matrix constrains expansion and maintains structural integrity during cycling.
Solution Approach 2:
The patent employs composite materials by combining alloy particles with carbon-containing material to form a composite anode active material. The alloy component (such as Si, Ge, Sn, or their alloys) provides high theoretical capacity for lithium insertion, while the carbon component forms a stable matrix that accommodates volume changes during charge-discharge cycles, preventing particle aggregation and maintaining electrical conductivity.
2Volume of stationary object
If the spirally wound electrode body is compactly wound to improve energy density, then the battery volume is reduced, but uneven pressure distribution occurs during anode expansion, causing separator compression and potential short-circuits
Solution Approach 1:
The patent applies beforehand cushioning by incorporating a buffer layer or flexible diaphragm between the electrode body and the battery case. This buffer structure is designed in advance to accommodate the expansion of the anode during charging, absorbing the mechanical stress before it can compress the separator and cause short-circuits. The buffer layer expands elastically to counterbalance the anode volume increase.
Solution Approach 2:
The patent uses flexible shells by employing a deformable diaphragm or flexible packaging structure that can dynamically adjust its volume during charge-discharge cycles. This flexible component absorbs the expansion stress of the anode through elastic deformation, maintaining uniform pressure distribution and preventing separator compression while keeping the battery compact.
3Quantity of substance
If the anode is allowed to expand freely during charging to achieve high capacity, then the lithium insertion capacity is improved, but the battery can is pressed from inside and deformed
Solution Approach 1:
The patent applies anti-weight by introducing a counteracting mechanical structure that opposes the expansion force of the anode. The flexible diaphragm or buffer layer acts as a counterweight system, providing an equal and opposite elastic force to balance the anode expansion pressure, preventing the battery can from being pressed and deformed while still allowing the anode to expand sufficiently for high lithium insertion capacity.
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 prevents pressure deviation and lithium precipitation, enhancing the charge and discharge cycle characteristics while maintaining sufficient capacity, thereby improving the battery's overall performance.
Implementation Method 1
a cathode having a cathode active material layer on a strip-shaped cathode current collector and an anode having an anode active material layer on a strip-shaped anode current collector are layered with a separator in between
Implementation Method 2
layered with a separator in between
Data Source
AI summary
A battery including: a spirally wound electrode body in which a cathode having a cathode active material layer on a strip-shaped cathode current collector and an anode having an anode active material layer on a strip-shaped anode current collector are layered with a separator in between, and spirally wound in a planular state; and a lead joined to the cathode current collector or the anode current collector in a center portion of the spirally wound electrode body. An inner circumferential end of the cathode active material layer is provided in a region where the inner circumferential end does not overlap with the lead in a short axis direction of the spirally wound electrode body.