All Solid Cell Anode Coating Prevents Lithium Precipitation
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Solution Overview
Problem
In all solid cells, the direct electrical contact between conductive materials and solid electrolytes leads to lithium precipitation, causing interfacial reactions and performance degradation, such as dendrite growth and reduced charge/discharge capacity.
Innovation Solution
An anode structure is developed with a conductive coating layer, primarily composed of nonconductive oxides like P2O5, B2O3, and SiO2, which prevents direct electrical contact between the conductive material and the solid electrolyte, thereby suppressing lithium generation. This structure includes a conductive material with a needle-like shape and an anode current collector, with the coating layer formed through heat-treating at temperatures between 300 to 700°C.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conductive material directly contacts the solid electrolyte in an all solid cell, then electrical conductivity is improved, but lithium precipitation occurs causing performance degradation
Solution Approach 1:
An oxide coating layer is introduced as an intermediary between the conductive material and the solid electrolyte. This coating layer prevents direct contact and lithium precipitation while maintaining electrical conductivity through the conductive material, thus resolving the contradiction between conductivity and lithium precipitation prevention
2Reliability
If a coating layer is added to prevent lithium precipitation, then cell performance is improved, but manufacturing complexity increases
Solution Approach 1:
The oxide coating layer is formed by controlling the sintering temperature (900-1100°C) of the electrode mixture, transforming the physical and chemical properties of the conductive material surface in situ. This parameter-based approach simplifies manufacturing compared to traditional multi-step coating processes
3Reliability
If graphite-based material is used as conductive material, then electrical conductivity is improved, but potential imbalance occurs leading to lithium precipitation
Solution Approach 1:
The oxide coating layer acts as a mediator that prevents the direct interaction between graphite-based conductive material and lithium ions in the solid electrolyte. This eliminates the potential imbalance issue while preserving the electrical conductivity benefits of graphite materials
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 solution effectively increases the charge/discharge capacity and lifespan of all solid cells by preventing lithium precipitation and subsequent degradation, as demonstrated by capacity measurements and stability tests.
Implementation Method 1
the conductive coating layer may, at least substantially, prevent the conductive material and the solid electrolyte from being electrically connected to each other
Implementation Method 2
forming a conductive coating layer on the conductive material by heat-treating at a temperature of about 300 to 700° C.
Data Source
AI summary
Provided are an anode for an all solid cell and a method of fabricating the same. The anode may include an anode current collector, a conductive material of which one end contacts a part of the anode current collector, a conductive coating layer surrounding the conductive material, an anode active material which contacts the other end of the conductive material, and a solid electrolyte. The conductive coating layer may prevent the conductive material and the solid electrolyte from being electrically connected to each other.