Sulfide Solid-State Lithium-Ion Cathode for Low Resistance
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Solution Overview
Problem
Lithium-ion batteries using a positive electrode active material with a Li-deficient O2-type structure face challenges with resistance.
Innovation Solution
A lithium-ion battery design incorporating a positive electrode active material layer with a Li-deficient O2-type structure and a sulfide solid electrolyte, where the Raman spectrum and XPS spectrum satisfy specific intensity ratios, and the positive electrode active material layer is pressed at a temperature below 165°C.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a positive electrode active material with a Li-deficient O2-type structure is used, then the battery capacity is improved, but the resistance increases
Solution Approach 1:
The patent changes the chemical composition parameters of the positive electrode active material by controlling the Li/O ratio to be less than 0.5, creating a Li-deficient O2-type structure. This parameter change enables higher battery capacity while the resulting improved electrochemical performance actually reduces resistance, resolving the technical contradiction.
Solution Approach 2:
The patent employs a composite positive electrode active material comprising multiple elements (Li, Na, Mn, Ni, Co, Al) in specific ratios to form a Li-deficient O2-type structure. This composite material approach achieves both high capacity and low resistance by optimizing the synergistic effects of different elements.
2Manufacturing precision
If the positive electrode active material layer is pressed at high temperature, then the density is improved, but the PS4 skeleton of the sulfide solid electrolyte is damaged and resistance increases
Solution Approach 1:
The patent changes the pressing temperature parameter from conventional high temperatures to a specific range of 100°C to 160°C. This parameter change allows achieving sufficient density while preserving the PS4 skeleton structure of the sulfide solid electrolyte, thereby maintaining low resistance.
Solution Approach 2:
The patent applies preliminary anti-action by carefully controlling the pressing temperature to prevent the thermal degradation of the sulfide solid electrolyte before it can occur. By staying below the critical temperature threshold that would damage the PS4 skeleton, the patent prevents resistance increase while still achieving adequate density.
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 battery achieves low resistance, as evidenced by the Raman and XPS spectrum ratios, indicating effective maintenance of the sulfide solid electrolyte's PS4 skeleton and suppression of reactions that increase resistance.
Implementation Method 1
pressing the positive electrode mixture at a temperature of lower than 165° C. to obtain a positive electrode active material layer
Implementation Method 2
A Raman spectrum of the positive electrode active material layer satisfies relationships (1) and (2) below: IR1: peak intensity from P2S6 4− in the Raman spectrum; IR2: peak intensity from PS4 3− in the Raman spectrum; IR3: peak intensity from S—S in the Raman spectrum
Implementation Method 3
an XPS spectrum of the positive electrode active material layer satisfies relationships (3) and (4) below: IX1: peak intensity from P—S—P in the XPS spectrum for S2p; IX2: peak intensity from PS4 3− in the XPS spectrum for S2p; IX3: peak intensity from POxS4−x 3− in the XPS spectrum for P2p; IX4: peak intensity from PS4 3− in the XPS spectrum for P2p
Data Source
AI summary
A lithium-ion battery having low resistance is disclosed. The lithium-ion battery of the present disclosure comprises a positive electrode active material layer, an electrolyte layer, and a negative electrode active material layer, wherein the positive electrode active material layer comprises a positive electrode active material having a Li-deficient O2-type structure and a sulfide solid electrolyte, and a Raman spectrum of the positive electrode active material layer satisfies relationships of IR1/IR2≤0.20 and IR3/IR2≤0.20 (IR1: peak intensity from P2S64− in the Raman spectrum, IR2: peak intensity from PS43− in the Raman spectrum, and IR3: peak intensity from S—S in the Raman spectrum).