Uniformly Modified Silicon Composite for Stable Fast-Charging Anodes
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Solution Overview
Problem
Silicon-based materials for lithium-ion batteries face challenges due to significant volume changes during lithium deintercalation, leading to pulverization and low first-cycle efficiency.
Innovation Solution
A uniformly modified silicon-based composite material (SiCxAyOz) is developed with carbon and A elements uniformly distributed on an atomic scale, improving electroconductivity and cycling stability through bulk-phase doping and a multi-phase dispersive microstructure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If silicon-based materials are used for high specific capacity, then the energy density of lithium-ion batteries is improved, but the volume change during lithium deintercalation causes pulverization and low first-cycle efficiency
Solution Approach 1:
The patent employs a nested structure where silicon particles are embedded within a carbon matrix, forming a core-shell configuration. The silicon core maintains high specific capacity while the carbon shell provides structural support and accommodates volume expansion, preventing pulverization during cycling. This nested architecture allows the inner silicon to perform its high-capacity function while the outer carbon layer protects against mechanical degradation.
Solution Approach 2:
The patent creates a composite material system combining silicon and carbon in a specific configuration. The composite structure leverages the high capacity of silicon while incorporating carbon's mechanical strength and flexibility to handle volume changes. This composite approach resolves the contradiction by integrating materials with complementary properties, where silicon provides electrochemical performance and carbon provides structural stability.
2Reliability
If carbon coating is applied to improve surface electroconductivity and buffer volume change, then cycling performance is improved, but the electroconductivity inside particles remains insufficient for rapid charging
Solution Approach 1:
The patent applies local quality by creating different carbon configurations in different regions of the material. The carbon coating on the surface provides mechanical buffering and surface conductivity, while the carbon distributed within the particle interior (through doping or internal structures) provides internal conductivity pathways. This spatial differentiation of carbon's functions simultaneously improves cycling performance through surface protection and enables rapid charging through internal conductive networks.
Data Source
AI summary
A silicon-based composite material includes SiCxAyOz, 0<x<20, 0<y<10 and 0<z<10. A is one or more of B, Al, Mg, Ca, Fe, Co, Ni, Cu, Zn, Ge, Sn and LiC is uniformly dispersed in the particles of the composite material at an atomic scale with no agglomerations of carbon atoms larger than 20 nm; the carbon atoms are combined with the silicon atom to generate disordered Si—C keys; the elemental silicon, elemental carbon, elemental A and elemental oxygen are uniformly distributed in the particle; the microstructure of the composite material is a multiphase dispersion structure; the average particle size of the composite material is 1 nm-100 μm, and the specific surface area of the composite material is 0.5 m2/g-40 m2/g; the mass of the carbon atoms accounts for 0.1%-40% of the mass of the composite material; the mass of the A atoms accounts for 3%-40% of the mass of the composite particle.