Solid-State Battery Graphite Anode Orientation for Interface Stability
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Solution Overview
Problem
Conventional all-solid-state batteries using granulated graphite particles as negative electrode active material face issues with lithium ion conduction and mechanical stress during charge and discharge, leading to reduced battery capacity and peeling at the electrode-electrolyte interface.
Innovation Solution
The battery design includes a negative electrode layer with flat active material particles oriented at angles of 0° to 30° to the thickness direction, accompanied by a solid electrolyte region to moderate stress and enhance lithium ion conduction, and a method for producing this layer involves mixing and forming a covering layer of solid electrolyte on the active material particles to prevent deformation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If granulated graphite particles are used as negative electrode active material, then the battery can be produced with conventional methods, but lithium ion conduction is hindered and peeling occurs at the electrode-electrolyte interface
Solution Approach 1:
The patent changes the shape parameter of the graphite particles from granulated (spherical) to flat plate-like shapes, and controls the orientation angle (0° to 30°) of these flat particles relative to the thickness direction. This parameter change improves lithium ion conduction paths while preventing interface peeling during charge-discharge cycles.
Solution Approach 2:
The patent creates a composite structure where flat graphite particles are embedded in a solid electrolyte matrix. The solid electrolyte fills the spaces between the flat particles and forms a composite negative electrode layer that maintains both electrical contact and mechanical stability, preventing peeling while enabling lithium ion conduction.
2Reliability
If flat active material particles are oriented at 0° to 30° to the thickness direction, then lithium ion conduction paths are maintained and peeling is reduced, but the manufacturing process becomes more complex
Solution Approach 1:
The patent applies preliminary action by pre-forming flat plate-like graphite particles before assembling the battery. These pre-formed flat particles are then oriented at specific angles (0° to 30°) during the electrode manufacturing process, which simplifies the overall process compared to attempting to orient granulated particles after assembly.
Solution Approach 2:
The patent controls the orientation angle parameter of the flat particles (0° to 30° relative to the thickness direction) to optimize both lithium ion conduction and mechanical stability. This parameter control is achieved through specific manufacturing techniques that align the flat particles during electrode formation, balancing performance improvement with manufacturing feasibility.
3Reliability
If solid electrolyte is used instead of organic electrolyte, then safety is improved and energy density increases, but production cost and complexity increase
Solution Approach 1:
The patent utilizes the porous structure of the solid electrolyte to fill spaces between flat graphite particles, creating a composite negative electrode layer. This porous solid electrolyte structure enables lithium ion conduction while maintaining mechanical integrity, achieving safety and energy density improvements without excessive complexity.
Solution Approach 2:
The patent creates a composite structure combining flat graphite particles with solid electrolyte material. This composite approach leverages the advantages of both materials: graphite provides high capacity while solid electrolyte provides safety and structural stability, achieving improved energy density and safety with manageable 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
This configuration maintains lithium ion conduction paths and reduces stress-induced peeling, thereby suppressing capacity reduction and improving battery performance, especially during high-rate discharge.
Implementation Method 1
a lithium ion battery including a solid electrolyte that conducts lithium (Li) ions
Data Source
AI summary
All-solid-state battery (100) has a structure in which positive electrode current collector (7), positive electrode layer (20) including positive electrode active material (2) and solid electrolyte (1), solid electrolyte layer (10) including solid electrolyte (5), negative electrode layer (30) including negative electrode active material (3) and solid electrolyte (4), and negative electrode current collector (8) are stacked in this order. Negative electrode active material (3) includes a plurality of flat active material particles having a structure of a plurality of stacked pieces of graphite. Negative electrode layer (30) has, in a cross section, active material orientation region (14) including two or more of a plurality of flat active material particles that are adjacently oriented. The major axis of each of the two or more flat active material particles has an angle of 0° or more and 30° or less with respect to the thickness direction of negative electrode layer (30).