Monocrystalline Cathode Material for High-Energy Lithium Batteries
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Solution Overview
Problem
Conventional Ni-based cathode active materials for lithium secondary batteries synthesized via co-precipitation methods suffer from micro-cracking, leading to interface exposure and side reactions, resulting in battery performance deterioration and limited high energy density characteristics due to secondary particle disintegration and excessive residual lithium.
Innovation Solution
A monocrystalline nickel-rich cathode active material represented by Li x P y Ni 1-a-b Co,A b O 2, where 0.98≤x≤1.02, 0<y≤0.007, 0<a≤0.2, 0≤b≤0.3, and A includes elements like Mn, Al, or V, is synthesized using a method involving a premixture of lithium and transition metal sources with a phosphorus source, thermally treated under oxidizing conditions to form single particles with a layered structure and reduced residual lithium content.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If electrode density is increased to greater than 3.3g/cc to implement high energy density, then energy density is improved, but secondary particles disintegrate and side reactions with liquid electrolyte increase, resulting in deterioration of initial lifetime characteristics
Solution Approach 1:
The patent changes the fundamental parameter of particle morphology from secondary particles to monocrystalline single particles. This structural parameter change enables the material to withstand high electrode density conditions without disintegration, while maintaining low side reaction rates and excellent initial lifetime characteristics.
Solution Approach 2:
The patent employs composite doping with multiple elements (P, B, and A elements such as Mn, Al, or V) within the monocrystalline structure. This composite approach optimizes both energy density and stability, allowing the material to achieve high capacity while resisting particle disintegration and side reactions.
2Ease of manufacture
If conventional co-precipitation method is used to synthesize Ni-based cathode active material, then manufacturing process is established, but micro-cracking occurs between secondary particles with repeated charging/discharging, leading to interface exposure and accelerated side reactions
Solution Approach 1:
The patent changes the particle morphology parameter from secondary particles to monocrystalline single particles through modified synthesis conditions. This fundamental structural change eliminates micro-cracking issues while maintaining manufacturing feasibility through a systematic thermal treatment process.
Solution Approach 2:
The patent applies preliminary thermal treatment at high temperature (900-1200°C) before final cathode material formation. This preliminary action creates a robust monocrystalline structure that prevents micro-cracking during subsequent charging/discharging cycles, ensuring long-term structural stability.
3Ease of manufacture
If excessive residual lithium compound (LiOH, Li2CO3) is present on surface of Ni-based cathode active material, then manufacturing is simplified, but carbon dioxide gas is generated during charging/discharging, significantly affecting battery stability
Solution Approach 1:
The patent performs preliminary high-temperature thermal treatment (900-1200°C) in an oxidizing atmosphere before final cathode material formation. This preliminary action completely removes residual lithium compounds from the surface, preventing CO2 gas generation during battery operation while maintaining manufacturing efficiency.
Solution Approach 2:
The patent uses an oxidizing atmosphere during thermal treatment to accelerate the removal of residual lithium compounds. The strong oxidation conditions at high temperature effectively eliminate LiOH and Li2CO3 from the surface, preventing harmful CO2 generation without requiring additional surface treatment steps.
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 monocrystalline cathode active material achieves a 20% increase in capacity per volume and improved stability and lifetime characteristics by preventing particle disintegration and reducing residual lithium, enabling higher energy density and longer battery life.
Implementation Method 1
thermally treated under oxidizing conditions to form single particles with a layered structure and reduced residual lithium content
Implementation Method 2
thermally treated under oxidizing conditions
Data Source
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AI summary
Provided is a monocrystalline cathode active material for a lithium secondary battery, the monocrystalline cathode active material being represented by the Formula of LixPyNi1-a-bCoaAbO2.