Solid-State Battery Anode with Fibrous Carbon
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Solution Overview
Problem
Existing methods for producing solid-state secondary batteries with Si alloy-based anode active materials face challenges in achieving high production efficiency while maintaining excellent cycle characteristics, particularly when initial charging is performed at high charge rates, leading to increased internal resistance due to local volume expansion and electron conducting path disruptions.
Innovation Solution
A method involving an anode material with at least elemental Si particles and fibrous carbon, where the fibrous carbon content is 4.8 vol % or more, is used to produce a solid-state battery system. This method includes disposing a solid electrolyte layer between the anode and cathode and performing initial constant current charging at a charge rate of 1.0 C or more to a voltage higher than the maximum charge voltage, ensuring the conductive additive can adapt to volume changes and maintain electroconductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If initial charging is carried out at a high charge rate, then production efficiency is improved, but internal resistance increases and cycle characteristics deteriorate
Solution Approach 1:
The patent applies preliminary action by conducting initial charging at a high charge rate (1.0 C or more) to a voltage higher than the maximum charge voltage controlled by the controller. This preliminary charging process forms a stable solid electrolyte interface (SEI) layer and activates the conductive additive network before normal operation, enabling subsequent high-rate charging without degradation. The anode material containing fibrous carbon (4.8 vol % or more) is prepared in advance to provide the necessary conductive framework that withstands the initial high-rate charging stress.
2Loss of time
If initial charging is carried out at a high charge rate, then charging time is reduced, but internal resistance increases due to local volume expansion
Solution Approach 1:
The patent employs composite materials by combining elemental Si particles (anode active material) with fibrous carbon (conductive additive material) in a specific composition where fibrous carbon content is 4.8 vol % or more. This composite structure allows the Si particles to undergo volume expansion during initial charging while the fibrous carbon network maintains electrical conductivity and provides mechanical support, preventing the formation of high-resistance regions and enabling fast charging without excessive internal resistance increase.
3Productivity
If fibrous carbon content is increased to maintain electroconductivity, then production efficiency is improved, but active material content decreases
Solution Approach 1:
The patent applies parameter changes by optimizing the fibrous carbon content to a specific range (4.8 vol % or more, preferably 9.2 vol % or less). This parameter optimization ensures sufficient electrical conductivity and structural stability during initial high-rate charging while maximizing the proportion of active Si material. The specific volume percentage represents a carefully balanced parameter that simultaneously achieves fast charging capability and high capacity utilization.
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 approach results in a solid-state secondary battery system with improved cycle characteristics and reduced internal resistance, even when initial charging is conducted at higher charge rates, enhancing production efficiency and maintaining electroconductivity throughout the battery.
Implementation Method 1
a solid electrolyte layer disposed between the cathode and the anode
Implementation Method 2
A Si alloy-based active material that can form an alloy with Li
Implementation Method 3
a fibrous carbon serving as a conductive additive material
Data Source
AI summary
A method for producing a solid-state secondary battery system comprising a lithium ion solid-state battery that comprises a cathode, an anode and a solid electrolyte layer disposed between the cathode and the anode, and a controller for controlling charge and discharge voltages of the lithium ion solid-state battery in use, the method comprising: obtaining an anode member from an anode material which contains at least elemental Si particles serving as an anode active material and a fibrous carbon serving as a conductive additive material, and in which the contained fibrous carbon is 4.8 vol % or more, obtaining a battery member by disposing a solid electrolyte member between the anode member and a cathode member and attaching them, and carrying out initial constant current charging on the battery member, at a charge rate of 1.0 C or more, to a voltage higher than a maximum charge voltage controlled by the controller.