Silicon Anode Composition With Oxystarch Binder for Cycle Stability
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Solution Overview
Problem
Lithium ion batteries face challenges due to the dramatic expansion and contraction of silicon during lithiation/delithiation, leading to irreversible capacity loss and capacity decay, which is not effectively addressed by prelithiation methods that consume lithium from the cathode.
Innovation Solution
A novel anode composition comprising a silicon-based active material, oxystarch as a binder, and optionally carbon materials, which improves electrochemical properties by enhancing adhesion, dispersibility, and stability, thereby reducing irreversible capacity loss and improving cycling performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If silicon-based active material is used to achieve high capacity, then theoretical capacity is improved, but volumetric expansion and contraction during lithiation/delithiation causes irreversible capacity loss and capacity decay
Solution Approach 1:
The anode is prelithiated before battery assembly to pre-compensate for the irreversible capacity loss that will occur during initial cycling. This preliminary action of adding extra lithium to the anode ensures that the silicon-based active material has sufficient lithium reservoir to maintain capacity throughout cycling, resolving the contradiction between high theoretical capacity and cycling reliability
Solution Approach 2:
The invention changes the lithium content parameter in the anode by controlling the prelithiation degree (ε) to be greater than the irreversible capacity loss ratio. This parameter adjustment transforms the anode from a lithium-deficient state (which would cause continuous capacity decay) to a lithium-sufficient state that can withstand the volumetric changes of silicon during cycling
2Power
If nano-sized active materials are used to shorten diffusion length and enhance reaction kinetics, then power density is improved, but surface area increases leading to high irreversible capacity loss due to SEI formation
Solution Approach 1:
The anode is prelithiated before battery assembly to pre-compensate for the irreversible capacity loss that will occur during initial cycling. This preliminary action of adding extra lithium to the anode ensures that the silicon-based active material has sufficient lithium reservoir to maintain capacity throughout cycling, resolving the contradiction between high theoretical capacity and cycling reliability
Solution Approach 2:
The invention changes the lithium content parameter in the anode by controlling the prelithiation degree (ε) to be greater than the irreversible capacity loss ratio. This parameter adjustment transforms the anode from a lithium-deficient state (which would cause continuous capacity decay) to a lithium-sufficient state that can withstand the volumetric changes of silicon during cycling
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 anode composition exhibits excellent electrochemical properties, including enhanced cycling and rate performances, while being economically viable and environmentally friendly, with improved stability and integrity during volume changes.
Implementation Method 1
a binder, wherein the binder is oxystarch
Implementation Method 2
during the lithiation/delithiation processes, silicon undergoes dramatic expansion and contraction
Implementation Method 3
the formation of a solid electrode interface (SEI)
Data Source
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AI summary
Provided is an anode composition for lithium ion batteries, comprising a) a silicon-based active material； and b) a binder, wherein the binder is selected from the group consisting of oxystarch, locust bean gum, tara gum, karaya gum and any combination thereof. Also provided are a process for preparing an anode for lithium ion batteries and a lithium ion battery.