Capacity compensation additive and preparation method therefor, positive electrode sheet, battery, and electric device
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Solution Overview
Problem
Existing capacity compensation agents in batteries have poor conductivity and require high decomposition voltages, leading to irreversible changes in the positive-electrode active material and reduced cycling performance due to side reactions with the electrolyte solution.
Innovation Solution
A capacity compensation additive comprising a catalyst-containing carbon material coated on a capacity compensation agent, which improves conductivity and reduces decomposition voltage, allowing active ions to be released at lower voltages to compensate for SEI film formation losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing capacity compensation agents are used, then capacity compensation can be achieved, but conductivity is poor and decomposition voltage is high
Solution Approach 1:
The patent uses a composite material consisting of a capacity compensation agent (such as lithium carbonate, lithium oxalate, or sodium oxalate) combined with a conductive material (such as acetylene black, carbon nanotubes, or graphene). This composite structure improves the overall conductivity of the capacity compensation additive while maintaining its capacity compensation function, thereby reducing the decomposition voltage and avoiding side reactions with the electrolyte solution.
Solution Approach 2:
The patent modifies the physical and chemical parameters of the capacity compensation additive by controlling particle size distribution (Dv10, Dv50, Dv90 values) and composition ratios. By optimizing these parameters, the decomposition voltage is reduced and conductivity is improved, allowing the additive to release active ions at lower voltages without causing harmful side reactions.
2Quantity of substance
If high decomposition voltage is required for deintercalation of active ions, then capacity compensation can occur, but electrolyte side reactions and irreversible structural changes occur
Solution Approach 1:
The patent changes the decomposition voltage parameter of the capacity compensation additive by using materials with lower decomposition potentials (such as lithium carbonate, lithium oxalate, sodium oxalate) and optimizing their particle size and composition. This allows active ions to be released at lower voltages, preventing electrolyte decomposition and positive electrode material structure degradation while still achieving effective capacity compensation.
3Reliability
If capacity compensation agent is added to positive electrode plate, then active ion loss during SEI film formation is compensated, but conductivity remains poor
Solution Approach 1:
The patent creates a composite capacity compensation additive by combining capacity compensation agents (lithium carbonate, lithium oxalate, sodium oxalate) with conductive materials (acetylene black, carbon nanotubes, graphene). This composite structure provides both the active ion compensation capability needed for SEI film formation and the electrical conductivity required for good battery performance.
Solution Approach 2:
The patent optimizes the local composition and particle size distribution within the capacity compensation additive to achieve different properties in different regions. By controlling Dv10, Dv50, and Dv90 values, the additive achieves good conductivity in certain regions while maintaining active ion compensation capability in others, resolving the contradiction between conductivity and compensation effectiveness.
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 additive enhances battery capacity and cycling performance by reducing decomposition voltage, avoiding electrolyte side reactions and irreversible changes in the positive-electrode active material.
Implementation Method 1
the conductivity of the capacity compensation agent can be improved
Implementation Method 2
the catalyst and the capacity compensation agent are not easy to fall off from each other, which is beneficial to the exertion of the catalytic performance of the catalyst, and the conductivity of the capacity compensation agent can be improved, thereby reducing the decomposition voltage of the capacity compensation additive
Data Source
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AI summary
The present application discloses a capacity compensation additive and a preparation method therefor, as well as a positive electrode plate, a battery and an electrical apparatus. The capacity compensation additive includes a capacity compensation agent and a catalyst-containing carbon material, and the catalyst-containing carbon material is coated on at least a portion of a surface of the capacity compensation agent.