Prelithiated Silicon Oxide Particles for Low-Stress Li-Ion Anodes
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Solution Overview
Problem
Current silicon-based anode materials for lithium-ion batteries face significant volumetric expansion and contraction during cycling, leading to fatigue cracking, capacity fade, and limited cycle life, especially in high-energy applications, and existing pre-lithiation methods involve expensive and hazardous pure lithium.
Innovation Solution
A method of centrifugally distributing a molten precursor comprising silicon, lithium oxide, and optionally silicon dioxide in a centrifugal atomizing reactor to form prelithiated silicon oxide materials with a mixture of lithium silicide and lithium silicate, reducing the need for pure lithium and enhancing mechanical strength and cycle life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If pure lithium is used for pre-lithiation, then lithium consumption is reduced, but handling complexity and safety risks increase due to high reactivity
Solution Approach 1:
The patent replaces expensive and hazardous pure lithium with a more stable and easier to handle pre-lithiation agent that can be safely incorporated into the electrode manufacturing process. This substitute material achieves the same pre-lithiation effect without the handling complexities and safety risks associated with pure lithium metal.
2Quantity of substance
If silicon-based anode materials are used, then charge capacity is increased, but volumetric expansion and contraction lead to fatigue cracking and capacity fade
Solution Approach 1:
The patent applies pre-lithiation to the silicon-based anode material before electrode assembly. This preliminary action compensates for the lithium inventory loss that occurs during initial cycling and creates a buffer against the volumetric expansion and contraction stresses, thereby extending cycle life while maintaining high charge capacity.
Solution Approach 2:
The patent creates a composite anode structure combining silicon particles with a pre-lithiated matrix material. This composite approach allows the silicon to provide high charge capacity while the pre-lithiated matrix accommodates volumetric changes and prevents fatigue cracking, thereby improving both capacity and cycle life.
3Use of energy by moving object
If electrode loading levels are increased for high-energy applications, then energy density is improved, but volumetric changes cause decrepitation and loss of electrical contact
Solution Approach 1:
The patent develops a composite electrode structure where high-loading silicon particles are embedded in a pre-lithiated matrix material. This composite design allows the electrode to achieve high energy density through increased loading while the pre-lithiated matrix absorbs volumetric stresses and maintains electrical contact stability during cycling.
Solution Approach 2:
The pre-lithiation is performed before electrode assembly and high-loading application. This preliminary action creates a buffer inventory of lithium and establishes a mechanically stable matrix that can accommodate the high volumetric changes associated with high-loading silicon electrodes, preventing decrepitation and maintaining electrical contact.
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 method produces prelithiated silicon oxide materials with reduced lithium consumption and stress, improving mechanical properties and cycle life performance of lithium-ion batteries by forming both lithium silicide and silicate phases, thereby minimizing volumetric expansion and capacity fade.
Implementation Method 1
centrifugally distributing a molten precursor comprising silicon, lithium oxide, and optionally silicon dioxide in a centrifugal atomizing reactor
Implementation Method 2
solidifying the molten precursor to form a plurality of substantially round solid electroactive particles
Data Source
AI summary
Methods of making a negative electrode material for an electrochemical cell that cycles lithium ions is provided. The method may include centrifugally distributing a molten precursor comprising silicon, oxygen, and lithium by contacting the molten precursor with a rotating surface in a centrifugal atomizing reactor. The molten precursor is formed by combining lithium, silicon, and oxygen. For example, the precursor may be formed from a mixture comprising silicon dioxide (SiO2), lithium oxide (Li2O), and silicon (Si). The method may further include solidifying the molten precursor to form a plurality of substantially round solid electroactive particles comprising a mixture of lithium silicide (LiySi, where 0<y≤4.4) and a lithium silicate (Li4SiO4) and having a D50 diameter of less than or equal to about 20 micrometers.