Silicon Core Negative Electrode with Gradient Metal Oxide Coating
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Solution Overview
Problem
Current lithium-ion secondary batteries face challenges with the cycle characteristics and rapid charge-discharge capabilities of silicon (Si) negative electrode active materials, particularly due to the instability of SiO coatings and high equipment costs associated with vapor phase coating methods.
Innovation Solution
A negative electrode active material is developed with a core particle of silicon coated with a metal oxide or hydroxide, where the coating composition varies continuously from the center to the surface, formed using a sol-gel hydrolysis process and reduced through heat treatment, incorporating elements like Ge, Ni, and Co to enhance conductivity and interdiffusion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If SiO coating is used to improve cycle characteristics, then cycle stability is improved, but manufacturing cost and equipment complexity increase due to requiring CVD vapor phase coating equipment
Solution Approach 1:
The patent replaces the mechanical/vapor-phase coating system (CVD equipment) with a chemical solution-based coating system (sol-gel process). The coating is applied by immersing Si particles in a metal alkoxide solution followed by hydrolysis and heat treatment, eliminating the need for expensive vapor phase coating equipment while achieving stable SiO coating.
Solution Approach 2:
The patent uses inexpensive, readily available metal alkoxide solutions and simple heat treatment equipment instead of expensive CVD equipment. The coating process uses common laboratory equipment like beakers and hotplates, making the process accessible and cost-effective for widespread manufacturing.
2Stability of the object's composition
If vapor phase coating method is used to coat Si surface, then coating stability is improved, but manufacturing cost increases due to expensive equipment installation
Solution Approach 1:
The patent substitutes the complex vapor phase deposition system with a simple solution-based sol-gel process. The coating is formed by chemical hydrolysis of metal alkoxides in solution, followed by low-temperature heat treatment, replacing expensive CVD equipment with simple, inexpensive laboratory equipment.
Solution Approach 2:
The patent changes the coating process parameters from high-temperature vapor phase deposition to low-temperature solution-based hydrolysis and heat treatment. This parameter change enables the use of simple equipment while maintaining coating stability through controlled chemical reactions and thermal processing.
3Quantity of substance
If Si material is used to increase capacity, then battery capacity is improved, but rapid charge-discharge capability deteriorates
Solution Approach 1:
The patent creates a compositional gradient in the coating layer, with metal elements concentrated at the surface and SiO in the interior. This local quality distribution optimizes surface properties for rapid charge-discharge (through metal element conductivity) while maintaining interior stability (through SiO structure), thereby improving both capacity and rate capability.
Solution Approach 2:
The patent creates a composite coating structure combining SiO and metal elements (such as Ge, Ni, Co) with different functional properties. The SiO provides structural stability and capacity, while the metal elements enhance electrical conductivity and surface reactivity, enabling rapid charge-discharge capability.
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 improves the active material properties of silicon, enabling better cycle characteristics and rapid charge-discharge capabilities while reducing the complexity and cost of coating processes.
Implementation Method 1
reduced through heat treatment
Implementation Method 2
formed using a sol-gel hydrolysis process
Data Source
AI summary
A negative electrode active material includes a core particle comprising silicon; and at least one metal element selected from the group consisting of: Ge, Sn, Ni, Mo, W, Ag, Pd, Cu, Bi, Fe, Co, Mn, Cr, V, Ga, B, Sb, In, Te, Cd, Rh, Ru, Nb, Ta, Re, Os, Ir, Pt, Pb and P. The negative electrode active material has an elemental composition that varies continuously from a center of the core particle to a surface of the core particle. A negative electrode, a battery, an electric vehicle, an electric storage apparatus, an electronic apparatus and a power storage system each include the negative electrode active material.