Solid-State Battery Anode Composition for Volume-Stable Cycling
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Solution Overview
Problem
Existing lithium secondary batteries using liquid electrolytes are prone to fires and explosions, necessitating the development of all-solid secondary batteries with improved safety and cycle characteristics.
Innovation Solution
Incorporating a fibrous carbon-based material and a binder in the anode active material layer of all-solid secondary batteries, with a specific charge capacity ratio to the cathode active material layer, to stabilize the volume change during charging and discharging, thereby reducing internal resistance and enhancing cycle characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a liquid electrolyte is used in lithium secondary batteries, then high ionic conductivity and good electrochemical performance are achieved, but safety deteriorates due to increased likelihood of fires and explosions
Solution Approach 1:
The patent changes the physical state parameter of the electrolyte from liquid to solid, transforming it into a solid electrolyte. This parameter change fundamentally resolves the safety issue by eliminating the flammability inherent in liquid electrolytes, while maintaining ionic conductivity through careful selection of solid electrolyte materials and optimization of their composition and structure.
Solution Approach 2:
The patent employs composite material strategies by combining solid electrolytes with specific anode active materials and conductive additives. This composite approach ensures that the solid electrolyte system achieves both high safety and good electrochemical performance, overcoming the limitations of pure solid electrolytes through synergistic material combinations.
2Quantity of substance
If an anode active material layer with high charge capacity is used, then energy density is improved, but volume change during charging and discharging increases, deteriorating cycle characteristics
Solution Approach 1:
The patent introduces a fibrous carbon-based material that forms a flexible, conductive network around the anode active material particles. This fibrous structure acts as a buffer that accommodates volume expansion and contraction during lithium insertion and extraction, preventing structural degradation while maintaining electrical conductivity and enabling high charge capacity with stable cycle characteristics.
Solution Approach 2:
The fibrous carbon-based material serves as an intermediary between the anode active material particles and the solid electrolyte. It mediates the volume changes by providing a compliant interface that absorbs mechanical stress, prevents direct contact between expanding/contracting particles and the rigid solid electrolyte, thereby maintaining stable cycle performance while enabling high charge capacity.
3Duration of action of stationary object
If fibrous carbon-based material and binder are added to the anode active material layer, then volume change is stabilized and cycle characteristics improve, but device complexity increases
Solution Approach 1:
The patent merges multiple functions into the fibrous carbon-based material and binder system. The fibrous carbon provides both electrical conductivity and mechanical flexibility, while the binder ensures structural integrity. This combined approach stabilizes volume changes during cycling without requiring separate complex components, thereby improving cycle characteristics while minimizing the increase in device complexity.
Solution Approach 2:
The fibrous carbon-based material exhibits multi-functionality by simultaneously providing electrical conductivity, mechanical flexibility for volume accommodation, and structural support. This universal material performs multiple critical functions that would otherwise require separate components, thereby improving cycle characteristics without proportionally increasing device complexity.
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 integration of fibrous carbon-based materials and binders in the anode layer of all-solid secondary batteries effectively stabilizes volume changes, reduces internal resistance, and improves the cycle characteristics and safety of the batteries.
Implementation Method 1
Incorporating a fibrous carbon-based material and a binder in the anode active material layer of all-solid secondary batteries, with a specific charge capacity ratio to the cathode active material layer, to stabilize the volume change during charging and discharging
Implementation Method 2
a first anode active material (e.g., in a form of particles) and b) a second anode active material (e.g., in a form of particles), each of which (i.e., the first and second anode active materials) is capable of forming an alloy or a compound with lithium
Implementation Method 3
an anode and a cathode, each of the cathode and the anode including an active material capable of intercalating and deintercalating lithium ions
Implementation Method 4
Solid electrolytes have a lower possibility of ignition as compared with liquid electrolytes. All-solid secondary batteries using a solid electrolyte instead of a liquid electrolyte have been proposed.
Data Source
AI summary
An all-solid secondary battery includes a cathode layer, an anode layer, and a solid electrolyte layer between the cathode layer and the anode layer, wherein the cathode layer includes a cathode current collector and a cathode active material layer on a side of the cathode current collector, and the anode layer includes an anode current collector and a first anode active material layer on a side of the anode current collector, wherein the first anode active material layer includes a first anode active material and a second anode active material, each of which is capable of forming an alloy or a compound with lithium, and a fibrous carbon-based material, and a ratio (B/A) of an initial charge capacity (B) of the first anode active material layer to an initial charge capacity (A) of the cathode active material layer is in a range of about 0.01 to about 0.75.