Bi Anode Electrolyte Design for Better Lithium Battery Cycle Life
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Solution Overview
Problem
Lithium secondary batteries face challenges in achieving good cycle characteristics due to issues with electrode materials like graphite, which have low capacity density, and metals alloyed with lithium, which expand and contract, leading to pulverization and poor current collecting properties.
Innovation Solution
A battery configuration featuring a first electrode with a current collector and an active material layer containing bismuth (Bi) as the main component, combined with an electrolytic solution that includes vinylene carbonate or fluoroethylene carbonate, which maintains electron conduction paths and adhesion to the current collector, even during lithium occlusion and release.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If metals alloyed with lithium (aluminum, silicon, tin) are used as electrode materials to increase capacity density, then the capacity density is improved, but the metals expand and contract during charging and discharging, leading to pulverization and poor current collecting properties
Solution Approach 1:
The patent applies this principle by forming a flexible protective film on the surface of the alloy particles. This film accommodates the expansion and contraction of the alloy during lithium occlusion and release, preventing pulverization while maintaining electrical contact with the current collector throughout charge-discharge cycles.
Solution Approach 2:
The patent applies this principle by creating a composite structure where alloy particles are embedded in a matrix material or coated with protective layers. This composite approach combines the high capacity density of the alloy with the structural stability of the matrix, preventing pulverization while maintaining good current collecting properties.
2Reliability
If graphite is used as negative electrode material to prevent dendrite formation, then safety is improved, but the theoretical capacity density is only 372 mAh/g which is about 1/10 of lithium metal
Solution Approach 1:
The patent applies this principle by changing the electrode material from graphite to alloys with lithium (aluminum, silicon, tin, or their combinations). This parameter change increases the theoretical capacity density from 372 mAh/g to over 3,884 mAh/g for lithium metal equivalent capacity, while addressing safety concerns through protective film formation and composite结构设计.
Solution Approach 2:
The patent applies this principle by designing alloy-based electrodes that can serve multiple functions: achieving high capacity density, preventing dendrite formation through protective films, and maintaining structural integrity through composite结构设计. The alloy system provides both high capacity and safety features that were previously separate concerns.
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 results in batteries with improved cycle characteristics and higher capacity, as the Bi active material layer maintains contact with the current collector, preventing deterioration and enhancing electron conduction.
Implementation Method 1
the electrolytic solution contains at least one selected from the group consisting of vinylene carbonate and fluoroethylene carbonate
Implementation Method 2
an active material layer containing bismuth (Bi) as a main component... during lithium occlusion and release
Data Source
AI summary
A battery includes: a first electrode; a second electrode; and an electrolytic solution, wherein the first electrode includes a current collector and an active material layer, the active material layer contains Bi as a main component of an active material, and the electrolytic solution contains at least one selected from the group consisting of vinylene carbonate and fluoroethylene carbonate.