Carbon-Lithium Silicate Coated Silicon Particles for Lower Lithium Loss
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Solution Overview
Problem
Silicon oxides used in lithium-ion batteries suffer from irreversible lithium loss due to side reactions forming lithium silicates, leading to reduced initial charge-discharge efficiency.
Innovation Solution
A coating comprising carbon and lithium silicates is applied to silicon particles in a single step, resulting in a uniform core-shell structure that inhibits irreversible reactions and improves efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If silicon oxides are used as anode active material to improve energy density, then battery energy density is improved, but irreversible lithium loss occurs due to side reactions forming lithium silicates
Solution Approach 1:
The patent applies preliminary action by pre-coating silicon oxide particles with a carbon-containing layer before battery assembly. This coating is formed in advance through heating treatment, creating a protective barrier that prevents irreversible lithium silicate formation during initial battery cycling, thereby reducing lithium loss while maintaining high energy density
Solution Approach 2:
The carbon-containing coating serves as an intermediary layer between the silicon oxide particles and the electrolyte/lithium. This intermediate layer acts as a physical and chemical barrier that prevents direct harmful reactions between silicon oxide and lithium, allowing the system to achieve both high energy density and reduced lithium loss
2Reliability
If lithium doping of silicon oxides is performed to inhibit irreversible reactions, then initial charge-discharge efficiency is improved, but the process requires two steps and often needs inert atmosphere
Solution Approach 1:
The patent merges the coating formation and lithium doping processes into a single integrated step. By simultaneously introducing both carbon precursor and lithium source during one heating treatment, the method achieves the benefits of lithium doping (improved initial efficiency) while simplifying the overall process, eliminating the need for separate doping steps and inert atmosphere requirements
Solution Approach 2:
The patent changes the processing parameters by conducting the treatment in air atmosphere at controlled temperatures (e.g., 400-900°C) rather than requiring inert atmosphere. This parameter change simplifies the process conditions while still achieving effective coating formation and lithium doping in one step, improving both reliability and reducing process complexity
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 coating enhances the initial charge-discharge efficiency of silicon-based anode materials by reducing irreversible lithium loss and maintaining a stable lithium content.
Implementation Method 1
heating at least a portion of the wetted mixture to form the coating on the particles comprising silicon
Implementation Method 2
heating at least a portion of the wetted mixture to form the coating on the particles comprising silicon
Data Source
AI summary
This invention provides compositions comprising coated particles comprising silicon in which the coating is comprised of carbon and one or more lithium silicates, the coated particles comprising silicon having a carbon content of about 0.10 wt % or more and a lithium content of about 1 wt % or more, relative to the total weight of the coated particle. Processes for preparing these compositions are also provided.