Solid-State Lithium Battery Functional Layer Against Dendrites
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Solution Overview
Problem
Current lithium-deposition-type lithium secondary batteries do not achieve sufficient charge and discharge efficiency, despite advancements in the field.
Innovation Solution
Incorporating a pressurizing member to compress the battery elements and using a positive electrode active material layer sized smaller than the solid electrolyte layer, with a functional layer providing electronic insulation and lithium ion conductivity on the solid electrolyte surfaces, to prevent short circuits and enhance efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a solid electrolyte layer is used in a lithium-deposition-type battery, then safety against liquid leakage and short circuit is improved, but charge and discharge efficiency is insufficient
Solution Approach 1:
A functional layer is introduced as an intermediary between the solid electrolyte layer and the negative electrode current collector. This functional layer mediates the interaction between lithium metal and the solid electrolyte, preventing harmful reactions while maintaining high lithium ion conductivity, thus resolving the contradiction between safety and charge/discharge efficiency
Solution Approach 2:
The invention changes the physical and chemical parameters of the electrolyte system by transitioning from a single-layer solid electrolyte to a multi-layer structure with a functional layer. This parameter change enables both high safety (through solid electrolyte) and high charge/discharge efficiency (through the functional layer's optimized properties)
2Quantity of substance
If lithium metal is deposited on the negative electrode current collector, then energy density is improved, but dendrite formation occurs leading to internal resistance variation
Solution Approach 1:
The functional layer serves as a mediator between deposited lithium metal and the solid electrolyte, preventing direct contact and subsequent dendrite formation. This intermediary layer maintains uniform lithium deposition while preventing the growth of lithium dendrites that would cause internal resistance variation
Solution Approach 2:
The functional layer is placed beforehand between the negative electrode current collector and the solid electrolyte to prevent dendrite formation before it can occur. This pre-protective measure cushions against the harmful effects of lithium deposition irregularities
3Productivity
If a first electrolyte with high ion conductivity is used, then charge and discharge characteristics are improved, but lithium leakage and short circuit risk increase
Solution Approach 1:
The functional layer acts as an intermediary that allows high lithium ion conductivity to be maintained while preventing lithium leakage. It mediates the transport of lithium ions while containing the lithium metal, thus resolving the contradiction between charge/discharge characteristics and lithium leakage risk
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 significantly improves charge and discharge efficiency by preventing lithium dendrite formation and reducing internal resistance, leading to enhanced battery performance.
Implementation Method 1
The solid electrolyte is a material mainly made of an ion conductor that enables ion conduction in a solid
Implementation Method 2
a pressurizing member that pressurizes the power-generating element at a predetermined pressure in a direction of lamination thereof
Implementation Method 3
lithium metal is deposited on the negative electrode current collector during charging
Implementation Method 4
a positive electrode active material layer containing a positive electrode active material capable of absorbing and desorbing lithium ions
Data Source
AI summary
A lithium secondary battery includes: a power-generating element with a positive electrode having a positive electrode active material, a negative electrode having a negative electrode current collector, where lithium metal is deposited during charging, and a solid electrolyte layer interposed between the positive electrode and the negative electrode. A pressurizing member pressurizes the power-generating element at a predetermined pressure in a lamination direction. A part of an outer peripheral end of the positive electrode active material is located inside an outer peripheral end of the solid electrolyte layer, and a first functional layer is provided on a part of the solid electrolyte layer facing the negative electrode current collector and at least a part of a side surface of the solid electrolyte layer. The first functional layer has electronic insulation properties and lithium ion conductivity and is more stable in reductive decomposition due to contact with lithium metal.