Positive Electrode Composite Coating for Stable Solid-State Battery Resistance
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Solution Overview
Problem
Solid-state batteries using conventional positive electrode materials face high initial resistance and increased resistance with repeated charging/discharging, especially when conductive additives are used to reduce resistance.
Innovation Solution
A positive electrode material comprising a positive electrode active material complex with a conductive additive covered by a sulfide solid electrolyte containing Li, Ti, and X (where X is Ca, Mg, Al, Y, or Zr), where the solid electrolyte covers the conductive additive, ensuring low initial resistance and preventing resistance increase during cycling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conductive additive is added to reduce resistance, then initial resistance decreases, but resistance increases easily with repeated charging/discharging
Solution Approach 1:
A solid electrolyte coating layer is introduced as an intermediary between the conductive additive and the positive electrode active material. This coating layer prevents direct contact and potential degradation reactions between the conductive additive and active material during cycling, while still allowing ionic transport. The solid electrolyte acts as a protective mediator that maintains low resistance initially and prevents resistance increase during repeated charging/discharging operations.
Solution Approach 2:
The positive electrode material employs a composite structure consisting of multiple components: positive electrode active material particles, conductive additive, and solid electrolyte coating. This composite material design combines the electrical conductivity of the conductive additive with the protective and ion-conducting properties of the solid electrolyte, achieving both low initial resistance and long-term stability during cycling.
2Duration of action of stationary object
If a solid electrolyte coating is applied to cover the conductive additive, then resistance stability during cycling improves, but manufacturing complexity increases
Solution Approach 1:
The solid electrolyte coating is applied by combining the solid electrolyte powder with a solvent to form a slurry, which is then mixed with the positive electrode active material and conductive additive. This merging approach integrates the coating step into the existing electrode fabrication process, avoiding the need for separate complex coating equipment or multiple processing stages.
Solution Approach 2:
The solid electrolyte coating is formed by controlling the solvent evaporation process and drying conditions. By adjusting parameters such as drying temperature, time, and atmosphere, the coating achieves optimal thickness and uniformity. This parameter-based control simplifies the manufacturing process compared to requiring precise mechanical or chemical vapor deposition techniques.
Data Source
AI summary
There is provided a positive electrode material that can be used to manufacture a solid-state battery whose initial resistance is kept low and at which it is difficult for resistance to increase even if charging/discharging are repeated. The positive electrode material of the present disclosure contains a positive electrode active material complex and a sulfide solid electrolyte. The positive electrode active material complex contains: a positive electrode active material, a conductive additive covering at least a portion of a surface of the positive electrode active material, and a solid electrolyte covering at least a portion of the conductive additive. The solid electrolyte contains Li, Ti, X and F. The X is at least one selected from the group consisting of Ca, Mg, Al, Y and Zr.