Lithium-Ion Battery Anode With Metal Sulfide Additive for Cycle Stability
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Solution Overview
Problem
Lithium ion batteries face challenges with capacity and cycle performance due to the expansion of negative electrode materials like silicon alloys during charge and discharge, leading to capacity decay and impedance issues.
Innovation Solution
Incorporating a metal sulfide additive, such as copper sulfide or cuprous sulfide, into the negative electrode active material layer or applying it on the surface, which forms a conductive network and reduces impedance, preventing positive electrode metal ion dissolution and alleviating volume expansion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If silicon alloy material is used as negative electrode to increase capacity, then capacity is improved, but volume expansion during cycle occurs leading to particle pulverization and capacity decay
Solution Approach 1:
The patent uses a composite structure where silicon alloy particles are embedded in a carbon matrix. The carbon material provides structural stability and accommodates volume expansion, while silicon alloy provides high capacity. This composite approach resolves the contradiction by combining the high capacity of silicon with the structural stability of carbon.
Solution Approach 2:
The patent employs a carbon coating layer as a flexible shell around silicon alloy particles. This thin film structure allows for volume expansion during lithiation while maintaining particle integrity and preventing pulverization. The flexible carbon shell accommodates dimensional changes without causing particle failure.
2Reliability
If carbon material is used as negative electrode to ensure long cycle life, then cycle performance is improved, but capacity is limited and further increase is challenging
Solution Approach 1:
The patent merges carbon material with silicon alloy material in a composite structure. The carbon provides long cycle life while silicon alloy contributes high capacity. By combining these two materials, the patent achieves both extended cycle life and increased capacity, resolving the limitation of pure carbon electrodes.
Solution Approach 2:
The patent creates local regions of high-capacity silicon alloy within the stable carbon matrix. The silicon alloy is distributed as particles or regions throughout the carbon structure, providing localized high capacity while the surrounding carbon maintains overall structural stability and long cycle life.
3Reliability
If additive is added to reduce impedance and improve capacity, then conductivity is improved, but device complexity increases
Solution Approach 1:
The carbon matrix serves multiple functions simultaneously: it provides structural stability, accommodates volume expansion, conducts electrons, and binds silicon particles together. This multi-functionality reduces the need for separate additives for each function, thereby reducing overall complexity while maintaining improved conductivity and capacity.
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
This approach enhances the cycle performance and capacity retention of lithium ion batteries by improving ion and electron transport, maintaining high capacity while lowering impedance.
Implementation Method 1
using a metal sulfide having high conductivity and inercalation/deintercalation of lithium as an additive... advantageous in reducing impedance and exerting a higher capacity
Implementation Method 2
metal sulfide having high conductivity and inercalation/deintercalation of lithium
Implementation Method 3
the sulfur ions in the additive may precipitate the positive electrode metal ions to prevent dissolution on the surface of the negative electrode
Implementation Method 4
the additive is combined with a negative electrode active material capable of intercalating and deintercalating lithium... provides a fast path for the transmission of electrons and ions
Data Source
AI summary
A negative electrode including a negative electrode active material layer and an additive. The additive includes a metal sulfide. The additive is distributed in the negative electrode active material layer, and/or distributed on the surface of the negative electrode active material layer. The negative electrode effectively improves the performance of the lithium ion battery, and greatly improves the capacity and cycle performance of the lithium ion battery.