Silicon Negative Electrode Surface Layer for Battery Cycle Life
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Solution Overview
Problem
Silicon-based active materials for batteries have a high capacity per mass but suffer from corrosion issues due to reactions with the electrolyte, leading to a decrease in battery capacity over repeated charging and discharging.
Innovation Solution
A silicon-containing negative electrode active material is developed with a surface layer containing carbon and titanium or aluminum, which suppresses the reaction between silicon and the electrolyte, preventing corrosion product accumulation and maintaining battery capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If silicon-based active materials are used to increase capacity per mass, then battery capacity is improved, but corrosion products accumulate due to reaction with electrolyte during repeated charging and discharging
Solution Approach 1:
The invention applies composite materials by combining silicon-based active material particles with a carbon-containing surface layer that includes titanium or aluminum. This composite structure allows the silicon core to provide high capacity while the carbon-titanium or carbon-aluminum surface layer prevents corrosion from electrolyte reactions, thus resolving the contradiction between high capacity and cycle life stability
Solution Approach 2:
The carbon-containing surface layer acts as an intermediary between the silicon-based active material and the electrolyte. This intermediate layer prevents direct contact and harmful reactions between silicon and electrolyte, while still allowing lithium ion insertion and extraction, thereby protecting the silicon from corrosion during repeated charging and discharging cycles
2Reliability
If a surface layer containing carbon and titanium or aluminum is provided on silicon-based active material, then corrosion is suppressed and cycle life is improved, but manufacturing complexity increases
Solution Approach 1:
The invention applies preliminary action by forming the protective carbon-containing surface layer on the silicon-based active material particles before they are assembled into the battery. This pre-coating approach ensures that the silicon particles are already protected against electrolyte corrosion from the outset, simplifying the overall manufacturing process compared to post-assembly protection methods
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 proposed solution effectively prevents corrosion and maintains battery capacity over multiple charge-discharge cycles, enhancing the cycle life of nonaqueous electrolyte secondary batteries.
Implementation Method 1
it has been proposed that a surface treatment is carried out with a silane coupling agent, in order to enhance cycle characteristics of the silicon-based active material
Implementation Method 2
the electron conductivity between an additive current collector and the active material is imparted by, for example, adding a conductive auxiliary agent
Data Source
AI summary
Proposed is a novel negative electrode for nonaqueous electrolyte secondary batteries in which the battery capacity does not decrease even when charging and discharging are repeated. Proposed is a silicon-containing negative electrode active material for nonaqueous electrolyte secondary batteries, comprising negative electrode active material particles which are provided with a surface layer containing carbon and titanium or aluminum on the entirety or a portion of the surface of the active material.