Lithium Cobalt Oxide Cathode Blend for High-Voltage Cycle Stability
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Solution Overview
Problem
Lithium cobalt oxide positive electrode materials face rapid capacity fading and cycling performance drop when charge/discharge cut-off voltage exceeds 4.5 V, necessitating a material with stable electrochemical properties and higher energy density.
Innovation Solution
A positive electrode material is developed by mixing lithium cobalt oxide with O3 phase structure and O2 phase structure, where the O3 phase is doped with metal elements and coated with specific metal oxides, and the O2 phase is doped with Al, Mg, or Mn, to achieve improved capacity, rate, and cycling performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If lithium cobalt oxide with O2 phase structure is used, then capacity and rate performance are improved, but cycling performance deteriorates
Solution Approach 1:
The patent creates a composite positive electrode material containing both O2 phase lithium cobalt oxide (providing high capacity and rate performance) and O3 phase lithium cobalt oxide (providing stable cycling performance). This composite structure allows the material to simultaneously exhibit the advantages of both phases, resolving the contradiction between high capacity and good cycling stability.
2Use of energy by moving object
If charge/discharge cut-off voltage exceeds 4.5 V, then energy density is improved, but structural stability deteriorates
Solution Approach 1:
The composite structure combines O2 phase (high voltage capability) with O3 phase (structural stability at high voltage) lithium cobalt oxide, enabling the material to maintain structural integrity while operating at charge/discharge cut-off voltages exceeding 4.5 V, thus achieving high energy density without sacrificing structural stability.
Solution Approach 2:
The patent modifies the phase composition parameters of lithium cobalt oxide, creating a specific ratio of O2 and O3 phases that optimizes both voltage capability and structural stability, allowing operation at higher cut-off voltages for improved energy density.
3Reliability
If lithium cobalt oxide with O3 phase structure is used, then cycling performance is improved, but capacity deteriorates
Solution Approach 1:
The patent combines O3 phase lithium cobalt oxide (excellent cycling performance) with O2 phase lithium cobalt oxide (high capacity) in a composite structure, allowing the material to achieve both high capacity and superior cycling stability by leveraging the complementary strengths of both phases.
Data Source
AI summary
Disclosed are a positive electrode material, and a positive electrode plate including the positive electrode material and a battery. The positive electrode material including lithium cobalt oxide with an O3 phase structure and lithium cobalt oxide with an O2 phase structure in the present disclosure has a higher capacity and a significantly improved rate while also having excellent cycling performance.