BiNi Electrode Structure for Stable Cycling in Lithium Batteries
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Lithium secondary batteries face challenges in achieving improved cycle characteristics due to issues such as pulverization of active materials and poor discharge flatness, particularly when using bismuth as an active material, which results in low charge-discharge efficiency and severe cycle degradation.
Innovation Solution
The use of BiNi with a specific crystal structure belonging to the C2/m space group as the active material in the battery's electrode, which is formed by electroplating Bi on a nickel current collector and heat-treating it to diffuse Ni into the Bi layer, enhancing the adhesion to the current collector and reducing electron conduction path deterioration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If bismuth powder is used as the active material, then the battery can achieve high charge-discharge capacity, but the active material undergoes pulverization during charging and discharging, resulting in severe cycle degradation
Solution Approach 1:
The patent uses BiNi intermetallic compound as a composite material combining bismuth and nickel in a specific ratio (1:1 atomic ratio). This composite structure provides both high charge-discharge capacity from the bismuth component and improved structural stability from the nickel component, resolving the contradiction between capacity and cycle life.
Solution Approach 2:
The patent changes the crystal structure parameter of the active material by forming BiNi with a specific monoclinic crystal structure (space group C2/m). This parameter change in the crystal structure provides stable expansion and contraction behavior during lithium alloying and de-alloying, improving cycle characteristics while maintaining high capacity.
2Use of energy by moving object
If bismuth is used as the active material, then high energy density can be achieved, but poor discharge flatness results
Solution Approach 1:
The patent changes the crystal structure parameters by forming BiNi with monoclinic structure (space group C2/m), which provides more stable voltage platform during discharge. This structural parameter change improves discharge flatness while preserving the high energy density characteristic of bismuth-based materials.
3Quantity of substance
If silicon or tin is used as the electrode material, then high capacity can be achieved, but the electrode expands and contracts significantly, leading to poor cycle life
Solution Approach 1:
The patent creates a composite intermetallic compound BiNi where nickel provides structural stability and resistance to expansion/contraction, while bismuth provides high lithium alloying capacity. This composite approach resolves the contradiction between high capacity and structural stability.
Solution Approach 2:
The patent optimizes the local atomic arrangement in BiNi intermetallic compound, creating a specific monoclinic crystal structure where atoms are arranged to accommodate volume changes during lithium alloying. This local structural optimization allows high capacity while maintaining overall structural integrity for good cycle life.
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 improved cycle characteristics and higher capacity retention, with the BiNi battery exhibiting excellent discharge flatness and maintaining charge-discharge capacity over multiple cycles without significant deterioration.
Implementation Method 1
aluminum, silicon, tin, or the like that is electrochemically alloyed with lithium during charging
Implementation Method 2
formed by electroplating Bi on a nickel current collector
Implementation Method 3
heat-treating it to diffuse Ni into the Bi layer
Data Source
AI summary
A battery includes: a first electrode; a second electrode; and an electrolyte solution, wherein the first electrode includes a current collector and an active material layer, the active material layer contains BiNi, and the BiNi has a crystal structure, a space group of the crystal structure belonging to C2/m.