Solid-State Battery Anode Layer Composition for Low-Resistance Lithium Control
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Solution Overview
Problem
The growth of lithium dendrites in all-solid-state secondary batteries using lithium as an anode active material can lead to short circuits and capacity reduction, limiting the battery's performance and lifespan.
Innovation Solution
The all-solid-state secondary battery incorporates an anode active material layer with a mixture of lithium and amorphous carbon, where the weight ratio of lithium to amorphous carbon is between 1:3 and 1:1, and the anode layer has a sheet resistance of about 0.5 milliohms-centimeters or less.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If lithium is used as anode active material to increase energy density, then specific capacity increases about 10 times compared to graphite, but lithium dendrite growth causes short circuit and capacity reduction
Solution Approach 1:
The patent uses a composite anode structure combining lithium metal with carbon materials (graphite, amorphous carbon, or carbon nanotubes). The lithium provides high specific capacity while the carbon matrix prevents dendrite growth by providing a stable structure and uniform lithium distribution, thus resolving the contradiction between high capacity and short circuit prevention
Solution Approach 2:
The patent creates different regions within the anode with distinct functions: lithium-rich regions for high capacity and carbon-rich regions for structural stability and dendrite prevention. This local differentiation allows simultaneous achievement of high specific capacity and reliability by assigning specific properties to specific areas
2Weight of moving object
If lithium is used as anode active material, then battery weight or size decreases with increased output power, but lithium dendrite growth occurs during repeated charging and discharging
Solution Approach 1:
The composite anode of lithium and carbon maintains the lightweight advantage of lithium while the carbon component provides structural integrity during cycling, preventing dendrite-induced failure and extending battery lifespan. The carbon framework acts as a stable skeleton that accommodates lithium expansion and contraction without compromising structural stability
Solution Approach 2:
The carbon matrix serves as a pre-established protective structure that cushions and constrains lithium during volume changes. This beforehand cushioning prevents dendrite formation by providing a stable framework before any harmful growth can occur, thus extending battery life while maintaining lightweight characteristics
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 reduces the sheet resistance of the anode layer, enhances the binding force between the anode active material layer and the anode current collector, and improves the charge/discharge reaction speed, thereby inhibiting lithium dendrite growth and maintaining battery performance.
Implementation Method 1
the anode layer has sheet resistance of about 0.5 milliohms-centimeters or less
Implementation Method 2
a solid electrolyte layer disposed between the cathode active material layer and the anode active material layer
Data Source
AI summary
An all-solid-state secondary battery includes: a cathode layer including a cathode active material, an anode layer including an anode current collector and an anode active material layer disposed on the anode current collector, the anode active material layer including an anode active material and amorphous carbon, and a solid electrolyte layer disposed between the cathode active material layer and the anode active material layer, wherein a weight ratio of the anode active material to the amorphous carbon is 1:3 to 1:1, and the anode layer has sheet resistance of about 0.5 milliohms-centimeters or less.