Chromium-Doped Spinel Cathode for Lithium Ion Battery Capacity
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Solution Overview
Problem
Lithium ion batteries using lithiated cobalt oxide with a spinel-type crystal phase as cathode active material face insufficient discharge capacity due to limited volume change during charging/discharging.
Innovation Solution
A cathode active material comprising a spinel-type crystal phase with lithium, cobalt, chromium, and oxygen, represented by LiCoxCryMzO2±δ, where M is at least one of Al and Mn, with specific compositional ranges for x, y, and z, stabilizing the spinel-type crystal phase and enhancing battery capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If lithiated cobalt oxide with spinel-type crystal phase is used as cathode active material, then volume change during charging/discharging is small, but discharge capacity is insufficient
Solution Approach 1:
The patent modifies the compositional parameters of the spinel-type cathode material by controlling the ratio of divalent to trivalent metal ions (where sum equals 1-x and 0.85≤x<1). This parameter adjustment optimizes both the structural stability and discharge capacity, resolving the contradiction between volume stability and capacity.
Solution Approach 2:
The patent employs composite spinel-type materials containing multiple metal elements (Co, Mn, Al, Ni, Zn, Cu, or Cr) in specific combinations. This composite approach allows simultaneous achievement of structural stability and enhanced discharge capacity by leveraging the complementary properties of different metal ions.
2Quantity of substance
If chromium is added to spinel-type lithiated cobalt oxide, then discharge capacity increases significantly, but crystal phase stability may be compromised
Solution Approach 1:
The patent precisely controls the chromium content within the compositional framework where divalent and trivalent metal ions sum to (1-x) with 0.85≤x<1. This parameter control ensures chromium enhances capacity without destabilizing the spinel structure.
Solution Approach 2:
The patent introduces chromium at specific compositional positions within the spinel structure, creating local compositional variations that enhance capacity while maintaining overall structural stability through the balanced metal ion ratio.
Data Source
AI summary
When spinel-type lithiated cobalt oxide is employed for a cathode active material for a lithium ion battery, a sufficient discharge capacity is not always obtained. Thus, spinel-type lithiated cobalt oxide is doped with at least chromium, and specifically, a cathode active material for a lithium ion battery includes a spinel-type crystal phase including lithium, cobalt, chromium and oxygen, and the cathode active material has a composition represented by LiCoxCryMzO2±δ where M is at least one selected from Al and Mn, and 0.85≤x<1, 0<y≤0.15, 0≤z, and 0.85<x+y+z≤1.2.