Li5FeO4 Cathode Coating for Lower Resistance and Lithium Release
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Solution Overview
Problem
Lithium iron complex oxides exhibit high resistance and insufficient irreversible capacity, limiting their effectiveness as pre-doped materials in lithium-ion secondary batteries.
Innovation Solution
A lithium iron complex oxide represented by Li5FeO4 with specific quadrupole splitting values and isomer shift values, coated with lithium silicate or diamond-like carbon, to enhance irreversible capacity and reduce resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If lithium iron complex oxide is used as cathode material, then it can provide lithium ions for the battery, but the resistance is high and irreversible capacity is insufficient
Solution Approach 1:
The patent applies parameter changes by controlling the particle size of lithium iron complex oxide to be 1 μm or less, and adjusting the sintering temperature to 600-800°C. These parameter modifications optimize the material's electrical conductivity and irreversible capacity, resolving the contradiction between high resistance and sufficient lithium ion release capability.
Solution Approach 2:
The patent uses composite materials by combining lithium iron complex oxide with conductive carbon materials and other metal oxides. This composite approach improves the overall electrical conductivity of the cathode material while maintaining its lithium ion release capability, thereby reducing resistance and enhancing irreversible capacity simultaneously.
2Quantity of substance
If graphite is used as anode active material, then it has excellent life and output characteristics, but the capacity has reached theoretical value
Solution Approach 1:
The patent applies preliminary action by pre-doping lithium into the cathode material using lithium iron complex oxide before battery operation. This preliminary lithium insertion ensures that sufficient lithium ions are available from the cathode side, enabling the anode to achieve higher capacity without compromising cycle life, as the lithium supply is guaranteed from the outset.
3Quantity of substance
If alloy-based anode active materials are used, then capacity increases several to ten times, but irreversible structural changes occur and lithium ions are trapped
Solution Approach 1:
The patent applies preliminary anti-action by pre-inserting lithium ions into the cathode material using lithium iron complex oxide before the alloy anode undergoes structural changes. This preliminary lithium presence compensates for the lithium that would otherwise be trapped during initial charging, preventing the net loss of capacity while allowing the alloy anode to maintain its high capacity potential and structural transformation.
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 modified lithium iron complex oxide increases irreversible capacity and improves the performance of lithium-ion secondary batteries by enhancing lithium ion release and reducing resistance.
Implementation Method 1
the lithium iron complex oxide having a large irreversible capacity at the time of initial charging/discharging is used for the cathode
Implementation Method 2
in order to improve the high resistance of the lithium iron complex oxide, carbon coating by chemical vapor deposition is performed to improve the characteristics
Data Source
AI summary
A lithium iron complex oxide is represented by Li5FeO4, two peaks with different quadrupole splitting values (QS) analyzed using 57Fe Mössbauer spectroscopy are shown, one of the two peaks, a peak A, satisfies QS>0, and the other one of the two peaks, a peak B, satisfies QS=0.