All-Solid-State Battery Cathode Mixture for Low Resistance
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Solution Overview
Problem
Conventional all-solid-state lithium ion secondary batteries exhibit high resistance at low battery capacity (low SOC), which affects initial discharge capacity, initial output, and durability.
Innovation Solution
Doping the anode of the battery with lithium by releasing lithium ions from a cathode mixture at a lower potential, achieved by mixing a sulfide solid electrolyte with a conductive assistant using higher energy than usual, allowing lithium ions to reach the anode at a low voltage, thereby reducing battery resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional mixing energy is used for sulfide solid electrolyte, then manufacturing process is simple, but battery resistance at low SOC is high
Solution Approach 1:
The patent applies preliminary action by performing high-energy mixing of sulfide solid electrolyte with conductive assistant before cathode assembly to pre-release lithium ions. This preliminary treatment modifies the sulfide solid electrolyte's properties in advance, enabling it to release lithium ions at lower potentials during subsequent battery operation, thereby reducing resistance at low SOC without requiring changes to the overall battery structure or operation mode.
Solution Approach 2:
The patent utilizes parameter changes by altering the mixing energy parameter during cathode preparation. By increasing the mixing energy input to a specific threshold, the sulfide solid electrolyte undergoes structural modifications that enable lithium ion release at lower potentials. This parameter change transforms the sulfide solid electrolyte from a passive component to an active lithium source that operates effectively at low SOC conditions.
2Reliability
If high energy is added to sulfide solid electrolyte in mixing, then lithium ions are released at lower potential, but manufacturing complexity increases
Solution Approach 1:
The high-energy mixing step is performed as a preliminary action during cathode manufacturing, combining material preparation and functional modification in a single process stage. This approach integrates the complex mixing requirement into the existing manufacturing workflow, avoiding the need for separate additional processing steps and minimizing overall manufacturing complexity while achieving the desired lithium ion release behavior.
3Reliability
If anode is doped with lithium at low voltage, then battery resistance decreases, but charge-discharge voltage range is reduced
Solution Approach 1:
The patent uses preliminary action to dope the anode with lithium during the first charge at low voltage through the high-energy mixed sulfide solid electrolyte's lithium ion release. This preliminary doping establishes low resistance conditions for subsequent operations. The voltage range loss is confined to this initial charging phase, after which the battery operates within its normal voltage range with improved performance 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 method lowers battery resistance at low capacity, improves initial discharge capacity and durability, and allows efficient electrochemical reactions at voltages below the battery's lower-limit voltage.
Implementation Method 1
the mixture can release lithium ions at a potential lower than the potential at which the cathode active material releases and occludes lithium ions
Data Source
AI summary
A method is provided where an anode of an all-solid-state lithium ion secondary battery is easily doped with lithium and to provide a small resistance at a low battery capacity. The method includes a manufacturing method of a cathode including mixing at least a conductive assistant (C1) and a sulfide solid electrolyte (E1) to obtain a mixture; and mixing at least one cathode active material, a solid electrolyte (E2) and the mixture obtained from the first step to obtain a cathode mixture, wherein an amount of energy added to the sulfide solid electrolyte (E1) is larger than an amount of energy added to the solid electrolyte (E2), and the mixture is a material that releases lithium ions at a potential lower than a potential at which the cathode active material releases and occludes lithium ions. Manufacturing methods for a cathode and an all-solid-state lithium ion secondary battery including the cathode mixture are also disclosed.