Silicon Oxide Anode Composites for Irreversible Capacity Loss
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Solution Overview
Problem
Existing negative electrode materials for lithium ion batteries, particularly silicon, suffer from high irreversible capacity loss and poor discharge and recharge cycling due to structural changes and large volume expansions, leading to decreased cycling efficiency.
Innovation Solution
The use of silicon oxide based active materials in combination with supplemental lithium, electrically conductive components, and smaller particle sizes, along with high energy mechanical milling and heat treatment, to form composites that stabilize the electrode structure and improve cycling performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If silicon based negative electrode material is used, then energy density is increased, but irreversible capacity loss increases and cycling performance deteriorates
Solution Approach 1:
The patent changes the chemical composition parameter by using silicon oxide (SiOx) instead of pure silicon, and controls the oxidation state parameter to reduce volume expansion during lithium intercalation, thereby maintaining high energy density while improving cycling stability
Solution Approach 2:
The patent creates composite materials by combining silicon oxide with conductive carbon materials and metal particles, forming a composite structure that maintains high capacity while improving electrical conductivity and structural stability during cycling
2Use of energy by moving object
If high capacity negative electrode materials are used, then energy density is increased, but structural integrity is destroyed due to volume expansion
Solution Approach 1:
The patent changes the oxidation state parameter of silicon from 0 in pure silicon to +2 or +4 in silicon oxide, which fundamentally alters the volume expansion behavior during lithium intercalation, reducing expansion from 300% in pure silicon to approximately 150% in SiOx
Solution Approach 2:
The patent introduces conductive carbon materials as an intermediary matrix that surrounds and supports the silicon oxide particles, absorbing volume expansion stress and maintaining structural integrity during cycling
3Reliability
If silicon oxide based composites are used, then cycling stability is improved, but electrical conductivity decreases
Solution Approach 1:
The patent creates composite materials by combining silicon oxide with conductive carbon materials and metal particles, forming a composite structure that maintains high capacity while improving electrical conductivity and structural stability during cycling
Solution Approach 2:
The patent introduces conductive carbon materials as an intermediary that provides electrical pathways between silicon oxide particles, mediating the electrical conductivity issue while maintaining the cycling stability benefits of silicon oxide
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 silicon oxide based composites exhibit improved cycling stability and high specific capacity, maintaining discharge capacity and reducing irreversible capacity loss, enabling the production of high energy density batteries suitable for commercial applications.
Implementation Method 1
lithium intercalation/alloying
Implementation Method 2
lithium intercalation/alloying
Implementation Method 3
high energy mechanical milling
Implementation Method 4
heat treatment
Data Source
AI summary
Silicon oxide based materials, including composites with various electrical conductive compositions, are formulated into desirable anodes. The anodes can be effectively combined into lithium ion batteries with high capacity cathode materials. In some formulations, supplemental lithium can be used to stabilize cycling as well as to reduce effects of first cycle irreversible capacity loss. Batteries are described with surprisingly good cycling properties with good specific capacities with respect to both cathode active weights and anode active weights.