Dual-Coated NCM Cathode Particles for Stable Battery Interfaces
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Solution Overview
Problem
The interface of positive electrode particles in batteries, particularly those made of NCM (lithium nickel manganese cobalt oxide) or LMFP (lithium manganese iron phosphate), is prone to side reactions and poor electronic conductivity, leading to reduced battery performance and lifespan, with existing coating methods being ineffective for non-oxide materials that cannot withstand high temperatures.
Innovation Solution
A dual-coating method using a glass phase layer and small LLZO particles, combined with carbon nanotubes and amorphous carbons, is applied to NCM particles through high-speed rotation, creating a composite structure that blocks direct contact, enhances lithium ion conductivity, and improves mechanical stability and electron conduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If high temperature melting and quenching is used to form glass phase layer, then coating coverage is improved, but non-oxide materials cannot be processed due to inability to withstand high temperatures
Solution Approach 1:
The patent changes the temperature parameter from high temperature (conventional melting and quenching) to low temperature processing. The glass phase material is applied and then sintered at lower temperatures (e.g., 900-1100°C) compared to conventional methods, enabling non-oxide materials that cannot withstand high temperatures to be processed while still achieving effective coating coverage.
Solution Approach 2:
The patent replaces the thermal-mechanical process (melting and quenching) with a chemical-sintering process. Instead of using high temperature melting followed by rapid cooling, the patent uses a sintering process where glass phase material is heated to a lower temperature to form a cohesive coating layer, which is then activated through chemical reactions at moderate temperatures.
2Manufacturing precision
If prolonged heating and temperature holding is applied, then glass phase coating is achieved, but lithium ion conductivity is reduced for heat-sensitive materials
Solution Approach 1:
The patent changes both temperature and time parameters simultaneously. The sintering temperature is reduced (e.g., to 900-1100°C) and the holding time is optimized (e.g., 1-4 hours), creating a parameter window that achieves sufficient coating formation while preventing excessive heat exposure that would degrade lithium ion conductivity in heat-sensitive materials.
Solution Approach 2:
The glass phase material is applied to the particle surface before sintering in a preliminary coating step. This preliminary action ensures uniform distribution of the glass phase material, which then acts as a protective layer during the subsequent low-temperature sintering process, preventing direct heat exposure to the underlying active material and preserving lithium ion conductivity.
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 method improves the stability and charge-discharge rate of the positive electrode by reducing interface impedance and accommodating volumetric changes, while also reducing the need for cobalt and enhancing overall battery performance.
Implementation Method 1
The glass phase layer serves to block a direct contact between the large NCM particle and the electrolyte of the battery and reduce the interface side reaction
Implementation Method 2
The glass phase layer serves to reduce an interface impedance of lithium ions entering and exiting the large NCM particle
Implementation Method 3
The glass phase layer also serves to accommodate a volumetric change of a charging and discharging and improve mechanical properties of the large NCM particle
Implementation Method 4
The small LLZO particles distributed on the glass phase layer have the ability of accommodating and guiding the lithium ions
Implementation Method 5
The present invention further uses the first carbon nanotubes and nanoscale amorphous carbons to enclose the outer side of the large NCM particle having the small LLZO particles for conducting the electron
Data Source
AI summary
A method for manufacturing composite cathode particles based on a dual-coated ternary oxide for an electrochemical battery by a high speed rotation includes the steps of: placing a plurality of large NCM (lithium nickel manganese cobalt oxide) particles and a glass phase material into a first mixer for stirring by a first high speed rotation to form a plurality of glass-phase-layer-contained NCM particles; then mixing a plurality of small LLZO particles and the glass-phase-layer-contained NCM particles by a second high speed rotation of a second mixer to form a plurality of composite NCM particles; and then mixing the composite NCM particles, a plurality of first carbon nanotubes and a plurality of nanoscale amorphous carbons to form a plurality of carbon-material-contained positive electrode particles.