LCO-LLZO-CNT Cathode Structure for High-Voltage Solid-State Conductivity
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Solution Overview
Problem
Conductivity of lithium batteries, particularly in solid-state and semi-solid batteries, is insufficient for practical use due to the ceramic nature of traditional positive particles, leading to reduced electron and ion transfer efficiency, increased internal resistance, and potential side reactions with electrolytes.
Innovation Solution
A LCO@oxide@CNT multicomposite cathode material is developed, where large LCO particles are coated with LLZO particles and an interphase layer, and further wrapped with carbon nanotubes, forming a conductive network to enhance electron and ion transfer, reduce side reactions, and improve stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional LCO particles are used in solid-state batteries, then the battery structure is simple, but the conductivity of lithium ions and electrons is insufficient
Solution Approach 1:
The patent applies composite materials by creating a multicomposite structure where LCO particles are coated with oxide materials (such as Al2O3, TiO2, or LiNbO3) and further wrapped with conductive materials (such as carbon coatings or metal nanoparticles). This composite structure simultaneously improves ionic conductivity through the oxide layer and electronic conductivity through the conductive material, resolving the contradiction between reliability and structural complexity.
Solution Approach 2:
The patent implements nesting by creating a hierarchical structure where the LCO particle is nested within an oxide coating layer, which is in turn nested within a conductive material layer. This nested configuration allows each layer to perform its specific function (ion transport, protection, electron conduction) while maintaining a compact integrated structure, addressing the conductivity issue without excessive complexity.
2Reliability
If positive particles are made more conductive through material modifications, then conductivity improves, but manufacturing complexity increases
Solution Approach 1:
The patent implements preliminary action by pre-coating the LCO particles with oxide materials before assembly into the battery structure. The oxide coating is applied in advance to protect the LCO particles and provide ionic conductivity pathways, while conductive materials are subsequently added to ensure electronic conductivity. This sequential pre-preparation of functional layers simplifies the overall manufacturing process compared to attempting to modify the bulk LCO material properties.
3Power
If high voltage operation (4.7V-4.9V) is enabled through improved conductivity, then energy density increases, but side reactions with electrolyte increase
Solution Approach 1:
The patent uses the oxide coating layer (such as Al2O3, TiO2, or LiNbO3) as an intermediary barrier between the LCO particles and the electrolyte. This intermediary layer is chemically stable at high voltages (4.7V-4.9V) and prevents direct contact between the reactive LCO surface and the electrolyte, thereby suppressing side reactions and gas generation while enabling high-voltage operation for increased energy density.
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 composite structure enhances ion and electron transfer, increases battery lifespan, improves voltage resistance, and ensures safe operation up to 4.7V-4.9V, reducing gas production and side reactions.
Implementation Method 1
the first LLZO interphase layer is formed between a bottom of each of the large LLZO particles and the large LCO particle; the first LLZO interphase layer serves to provide guiding channels for lithium ions
Implementation Method 2
the outer side of the composite LCO particles is further wrapped with an electron-conducting dielectric, which is a conductive network consisting of short chain and long chain carbon nanotubes with various lengths
Implementation Method 3
the LLZO particles and the interphase layer provide more protection, so that the overall positive electrode is not easy to react with the electrolyte, and is also not easy to be affected by the side reaction after the electrolyte disintegrates and reacts with the positive electrode under a high voltage
Data Source
AI summary
A LCO@oxide@CNT multicomposite cathode material which is a plurality of positive particles. Each of the positive particles comprises a composite LCO particle. The composite LCO particle includes a large LCO (lithium cobalt oxide, LiCoO2) particle, and a plurality of large LLZO particles and a plurality of small LLZO particles coated on a surface of the large LCO particle. Each of the large LLZO particles and small LLZO particles is formed by a LLZO (Li7La3Zr2O12) or a LLZO doped with at least one metal. A first LLZO interphase layer is formed between a bottom of each of the large LLZO particles and the large LCO particle. A second LLZO interphase layer is formed between a bottom of each of the small LLZO particles and the large LCO particle. An outer surface of each of the composite LCO particle is wrapped by a plurality of first carbon nanotubes.