Graphite-Zinc Negative Electrode for All-Solid-State Battery Cycle Stability
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Solution Overview
Problem
Conventional all-solid-state batteries using silicon as a negative electrode active material face deterioration in cycle characteristics due to expansion and contraction, leading to contact failures and reduced performance, while zinc, which has a lower volume expansion rate, has not been adequately studied for use in these batteries.
Innovation Solution
A battery configuration using a negative electrode composed of a mixture of graphite and zinc, with a mass ratio of zinc to the sum of graphite and zinc between 10% and 60%, and a solid electrolyte layer positioned between the positive and negative electrodes, enhances the cycle characteristics by improving the joined state at solid-solid interfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If silicon is used as a negative electrode active material to enhance energy density, then capacity increases, but cycle characteristics deteriorate due to expansion and contraction leading to contact failures
Solution Approach 1:
The negative electrode uses a composite material comprising both graphite and zinc in a specific mass ratio (10-60 mass% zinc). This composite structure combines the advantages of graphite (stable cycle characteristics, low expansion) with zinc (high capacity, lower expansion than silicon), achieving both high capacity and good cycle stability through material composition optimization
Solution Approach 2:
The invention optimizes the mass ratio parameter of zinc in the negative electrode to be 10-60 mass%. This parameter optimization balances the expansion characteristics and capacity contribution of zinc with the stability of graphite, preventing contact failures while maintaining high energy density
2Reliability
If zinc is used as a negative electrode active material to reduce volume expansion, then cycle characteristics improve, but the optimal composition ratio needs to be determined
Solution Approach 1:
The invention establishes a specific parameter range for zinc content (10-60 mass%) that optimizes the balance between capacity enhancement and expansion control. Within this range, the negative electrode achieves both improved cycle characteristics and reduced volume expansion without requiring complex composition optimization
3Reliability
If a solid electrolyte layer is used to improve safety and enable all-solid-state configuration, then reliability improves, but interface contact stability becomes critical
Solution Approach 1:
The negative electrode composite of graphite and zinc provides a more stable structural framework compared to pure silicon or zinc, reducing excessive expansion and contraction. This stability maintains reliable solid-solid interface contact with the solid electrolyte layer, ensuring consistent ion transmission and electrical contact throughout charge-discharge cycles
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 use of a graphite-zinc mixture in the specified mass ratio improves the cycle and input/output characteristics of the battery by reducing voids and enhancing the interface stability, leading to better performance and capacity retention.
Implementation Method 1
a solid electrolyte layer positioned between the positive electrode and the negative electrode
Implementation Method 2
deterioration in cycle characteristics due to expansion and contraction, leading to contact failures
Data Source
AI summary
A battery of the present disclosure includes a positive electrode, a negative electrode including graphite and zinc, and a solid electrolyte layer positioned between the positive electrode and the negative electrode. A ratio of a mass of zinc to a sum of a mass of graphite and the mass of zinc in the negative electrode is 10 mass % or more and 60 mass % or less. The above ratio may be 20 mass % or more and 40 mass % or less.