Anode Active Material Layer Width Optimization for Battery Safety
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Solution Overview
Problem
Current battery technologies face challenges in achieving high energy density while maintaining safety and preventing internal short circuits, particularly as energy density increases.
Innovation Solution
The battery design incorporates a cathode and anode with active material layers on strip-shaped current collectors, where the anode active material layer occupies regions overlapping with the cathode active material layer and has a narrower exposed region, reducing lithium metal precipitation and preventing short circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the anode active material layer is extended to the peripheral region beyond the cathode active material layer, then the energy density is improved, but the risk of internal short circuit and lithium metal precipitation increases
Solution Approach 1:
The patent applies local quality by creating different functional zones within the anode: a first region with anode active material layer directly opposing the cathode active material layer for high-capacity lithium insertion, and a second peripheral region with only current collector for current collection and safety. This spatial differentiation of material properties allows the battery to achieve high energy density in the active region while maintaining safety through the exposed current collector region that prevents lithium precipitation and short circuits.
2Reliability
If the exposed region of the anode current collector is made wider, then the safety is improved by preventing short circuits, but the energy density is reduced
Solution Approach 1:
The patent applies parameter changes by optimizing the width ratio between the first region (with active material) and the second region (exposed current collector). By carefully controlling this geometric parameter, the invention achieves the optimal balance where the exposed current collector region is sufficient to prevent short circuits and lithium precipitation, yet minimized to maintain high energy density. This quantitative optimization resolves the contradiction between safety and energy density.
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 design effectively prevents internal short circuits and maintains high energy density, ensuring both sufficient capacity and safety reliability.
Implementation Method 1
in charging, current concentration (flow of lithium ions) in an edge in the longitudinal direction of the anode active material layer is relaxed, precipitation of lithium metal in the anode is inhibited
Data Source
AI summary
A battery with more superior reliability is provided. The battery includes: a battery element 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, wherein the anode active material layer is provided to occupy a first region that is overlapped with a cathode active material layer formation region in which the cathode active material layer is provided on the cathode current collector and a peripheral region thereof in the anode, and out of a second region adjacent to the first region in the longitudinal direction in the anode, a width of a third region in which the anode active material layer is not formed and the anode current collector is exposed is smaller than a width of the first region.