Solid-State Battery Cathode Structure for Stable Electrolyte Contact
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Solution Overview
Problem
Current all-solid-state batteries face limitations in achieving satisfactory performance in terms of long-term cycle-life characteristics, high capacity, and high energy density due to the limitations of conventional positive electrode active materials.
Innovation Solution
A positive electrode for all-solid-state batteries is developed, comprising a lithium nickel-based composite oxide with radially arranged primary particles and single particles, combined with a solid electrolyte, conductive agent, and binder, which facilitates improved contact and connectivity, minimizing volume change during charging and discharging, and enhancing penetration of the electrolyte.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional positive electrode active materials are used, then the battery structure is simple and easy to manufacture, but the cycle-life characteristics, capacity, and energy density are insufficient
Solution Approach 1:
The positive electrode active material is divided into multiple primary particles that aggregate to form secondary particles. This segmentation allows each primary particle to maintain structural integrity during lithium insertion/extraction, while the aggregate structure provides overall stability, thereby improving cycle-life characteristics without excessive complexity
Solution Approach 2:
The patent uses composite lithium nickel-based materials with specific molecular structures (LiNi0.8Co0.1Mn0.1O2 with controlled crystalline structure). This composite approach combines the advantages of different metal oxides to achieve high capacity and long cycle-life while maintaining a manufacturable structure
2Quantity of substance
If high capacity and high energy density materials are used, then the energy density and capacity improve, but the volume change during charging and discharging increases causing separation between active material and solid electrolyte
Solution Approach 1:
The patent optimizes the crystalline structure parameters of the lithium nickel-based composite oxide, controlling the ratio of cubic to hexagonal phases and adjusting particle size distribution. These parameter changes enable high capacity while minimizing volume expansion during cycling, preventing separation from the solid electrolyte
Solution Approach 2:
Primary particles are nested within aggregates to form secondary particles with controlled morphology. This nested structure allows the inner primary particles to accommodate volume changes while the outer aggregate structure maintains overall dimensional stability, preventing electrolyte separation
3Quantity of substance
If particle components are closely packed to improve energy density, then the space between particles is minimized, but the contact property between solid electrolyte and active material deteriorates
Solution Approach 1:
The patent creates local quality variations in the positive electrode structure by forming aggregates with specific pore distributions and surface characteristics. The outer regions of aggregates have optimized surface area for electrolyte contact, while inner regions provide dense packing for high energy density, achieving both goals simultaneously
Data Source
Figure 1(A)~1(C)
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AI summary
Provided are a positive electrode for an all-solid-state battery, a method of preparing the same, and an all-solid-state battery including the same, the positive electrode for an all-solid-state battery includes a positive electrode active material including a first positive electrode active material including a lithium nickel-based composite oxide and being in a form of secondary particles in which a plurality of primary particles are aggregated and at least a portion of the primary particles are radially arranged, and a second positive electrode active material including a lithium nickel-based composite oxide and being in a form of single particles; a solid electrolyte; a conductive agent; and a binder.