Solid Electrode Surface Bonding for Battery Impedance Reduction
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Solution Overview
Problem
Existing oxide all solid-state lithium ion batteries face challenges in achieving high rate properties and favorable charge-discharge cycle performance due to low ion conductivity and chemical stability issues, particularly when attempting to reduce impedance through the use of solid electrolytes and sintering processes.
Innovation Solution
A secondary battery design featuring a positive electrode, negative electrode, and solid electrolyte layer with granular solid electrolytes and conduction aids bonded to the surface of electrode active substances, eliminating the need for a firing process and enhancing ion and electron conductivity without compromising chemical stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If sintering is performed to reduce resistivity in particle boundary, then physical and electrical bonding properties are improved, but chemical stability is impaired and charge-discharge cycle properties deteriorate
Solution Approach 1:
The invention introduces a conductor component in the surface layer before assembly, which preliminarily establishes electrical bonding pathways at particle boundaries. This preliminary action improves electrical bonding properties without requiring high-temperature sintering that would compromise chemical stability.
Solution Approach 2:
The conductor component acts as an intermediary substance between electrode active substance particles, facilitating electrical bonding at particle boundaries without requiring sintering. This intermediary approach improves bonding properties while preserving chemical stability.
2Productivity
If electrode is made thinner to minimize problems, then rate properties are improved, but amount of electrode active substance decreases, limiting rate properties
Solution Approach 1:
The invention creates a porous structure in the electrode with void spaces between particles. These voids allow electrolyte penetration and ion transport throughout the electrode volume, enabling high rate properties without requiring the electrode to be thin, thus preserving the amount of active substance.
Solution Approach 2:
The invention transitions from a two-dimensional thin film approach to a three-dimensional porous structure. This dimensional change allows ion transport through the bulk electrode volume via pores, enabling high rate properties while maintaining substantial active substance content.
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 solution results in a battery with improved rate properties and reduced impedance, enabling higher performance and longer cycle life without the drawbacks of sintering, such as chemical instability.
Implementation Method 1
a solid electrolyte which is a lithium ion conductor attracts attention... the lithium ion conductor constituting the solid electrolyte is a single ion conductor in which only a lithium ion moves
Implementation Method 2
an electron hardly passes through in a particle boundary between neighboring particles... the contact interface between the materials also increases. Accordingly, the electric resistance in the above particle boundary increases
Data Source
AI summary
There is provided a secondary battery including a positive electrode, a negative electrode, and a solid electrolyte layer disposed between the positive electrode and the negative electrode, wherein at least one of the positive electrode and the negative electrode contains a granular solid electrolyte and a granular conduction aid both bonded to a surface of a granular electrode active substance.