Solid-State Battery Anode Structure for Low-Pressure Contact Stability
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Solution Overview
Problem
The development of all-solid-state lithium secondary batteries faces challenges in achieving sufficient lithium ion diffusivity and maintaining contact between battery components due to volume changes during charging and discharging, leading to mechanical stress and degradation.
Innovation Solution
A solid state battery design incorporating bi-modal mixed particles of silicon-based first particles and softer second particles, which form discrete domains to compensate for size changes, maintaining contact and enabling lithium diffusion at lower pressures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high pressure is applied to maintain contact between battery components, then contact stability is improved, but mechanical stress and degradation increase
Solution Approach 1:
The patent changes the mechanical property parameter of the buffer material by selecting materials with specific elasticity moduli (softer than silicon particles) to compensate for volume changes. This parameter change allows the battery to maintain contact stability without requiring high external pressure, thereby reducing mechanical stress on components.
Solution Approach 2:
The patent introduces a buffer material as an intermediary component between the silicon particles and the solid electrolyte. This buffer material absorbs volume changes and maintains stable contact, acting as a mediator that prevents direct mechanical stress transmission to other battery components during charging and discharging cycles.
2Quantity of substance
If silicon particles are used as anode material to increase capacity, then energy density is improved, but volume changes during cycling cause loss of contact
Solution Approach 1:
The patent segments the anode structure by dispersing silicon particles individually or in small clusters within a matrix of buffer material. This segmentation prevents large-scale volume changes that would cause contact loss, while still utilizing the high capacity of silicon. The buffer material segments the stress distribution, maintaining contact stability throughout cycling.
Solution Approach 2:
The patent creates a composite anode structure combining silicon particles with buffer material having different mechanical properties. This composite structure leverages the high capacity of silicon while the buffer material compensates for volume changes, achieving both high energy density and stable contact during charging and discharging cycles.
3Strength
If pressure is reduced to minimize mechanical stress, then mechanical degradation is reduced, but contact between components is lost
Solution Approach 1:
The buffer material provides self-service by automatically compensating for volume changes of silicon particles during lithiation and delithiation. As silicon expands during charging, the buffer material compresses; as silicon shrinks during discharging, the buffer material expands. This self-adjusting mechanism maintains contact without requiring external pressure, enabling the battery to operate at low or zero pressure while preventing contact loss.
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 design enhances lithium ion diffusivity and maintains stable contact between battery components, improving the operational efficiency and longevity of the battery.
Implementation Method 1
second particles comprising a material configured to form an alloy with lithium
Implementation Method 2
The solid electrolyte is configured to enable transport of lithium ions between the cathode and the anode
Implementation Method 3
as the first particles expand in size, the second particles are compressed in size at a given pressure applied to the solid state battery and further such that, as the first particles shrink in size, the second particles expand in size
Data Source
AI summary
Solid state battery apparatus are provided. The present disclosure relates to a solid state battery comprising a cell which comprises a cathode, an anode, and a solid electrolyte positioned between the cathode and the anode. The anode comprises first particles comprising silicon and second particles comprising a material configured to form an alloy with lithium. The second particles are substantially softer than the first particles and configured to compensate for size changes of the first particles during charging and discharging cycles of the solid state battery such that, as the first particles expand in size, the second particles are compressed in size at a given pressure applied to the solid state battery and further such that, as the first particles shrink in size, the second particles expand in size at a given pressure applied to the solid state battery.