Zn-Mn Negative Electrode Composition for Capacity and Initial Efficiency
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Solution Overview
Problem
Secondary batteries using zinc alloys as negative electrode mixture layers exhibit insufficient discharge capacity and low initial charge-discharge efficiency.
Innovation Solution
A negative electrode active material comprising a zinc-manganese alloy with a molar ratio of Zn to Mn between 3 and 13, and containing 1000 ppm or less of Fe, is used to enhance the initial charge-discharge efficiency and discharge capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If zinc alloys are used as negative electrode mixture layer, then battery capacity can be increased, but initial charge-discharge efficiency becomes low
Solution Approach 1:
The invention changes the compositional parameters of the zinc alloy by strictly controlling the Fe content to 1000 ppm or less and optimizing the Zn:Mn molar ratio to 3:1 to 13:1. This parameter optimization resolves the contradiction by achieving both high battery capacity and high initial charge-discharge efficiency (95% or more), eliminating the inefficiency problem associated with conventional zinc alloys.
Solution Approach 2:
The invention uses a composite zinc-manganese alloy system where Zn and Mn work synergistically. The specific composition range (Zn:Mn molar ratio of 3:1 to 13:1 with Fe ≤ 1000 ppm) creates an optimized composite material that simultaneously achieves high capacity and high initial efficiency, resolving the trade-off between capacity and efficiency.
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 zinc-manganese alloy achieves higher initial charge-discharge efficiency and increased discharge capacity even during and after the second cycle, due to efficient Li occlusion and release mechanisms.
Implementation Method 1
During the charge, the zinc-manganese alloy in which a molar ratio of a Zn content to a Mn content is 3 to 13 occludes Li, and Zn and Li are bonded to form LiZn. During the discharge, Zn and Mn are recombined to release Li.
Data Source
AI summary
A nonaqueous electrolyte secondary battery according to the present invention is provided with a negative electrode, a positive electrode and a nonaqueous electrolyte. A negative electrode active material contained in the negative electrode contains a zinc manganese alloy containing Zn, Mn and Fe that is in an amount of 1,000 ppm or less of the total mass of Zn and Mn. With respect to the zinc manganese alloy, the molar ratio of the Zn content to the Mn content is from 3 to 13.