Porous Graphite Negative Electrode Material for Low-Temperature Charging
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Solution Overview
Problem
Lithium-ion batteries face challenges in maintaining high performance at low temperatures, particularly in terms of discharge rate and preventing lithium precipitation, due to limitations in existing negative electrode materials which often compromise between kinetic performance and energy density.
Innovation Solution
A negative electrode material with carbonaceous active particles featuring specific pore structures and distributions, including pore sizes between 0.3 μm and 2.0 μm, and a proportion of particles with 2-5 pores, ensures improved low-temperature charge and discharge performance while maintaining mechanical strength and energy density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the particle size of graphite is reduced to shorten the lithium intercalating path, then the kinetic performance is improved, but the energy density is reduced
Solution Approach 1:
The patent introduces a porous structure into the graphite particles with controlled pore sizes (0.5-2.0 μm) and specific pore quantities (1-5 pores per particle). This porous structure creates multiple lithium ion pathways within the particle, effectively shortening the intercalation path without reducing the overall particle size, thus maintaining energy density while improving kinetic performance
Solution Approach 2:
The patent changes the internal structure parameters of graphite particles by introducing pores with specific size ranges (0.5-2.0 μm) and controlling the number of pores (1-5 per particle). This structural parameter modification allows lithium ions to access the particle interior more efficiently through the pores, improving reaction kinetics without sacrificing the particle size needed for high energy density
2Productivity
If the negative electrode material is directly coated to improve kinetic performance, then the discharge rate is improved, but the manufacturing cost increases
Solution Approach 1:
The patent employs a porous graphite structure that can be manufactured through conventional processing methods without requiring complex coating operations. The porous structure is formed during graphite synthesis, allowing cost-effective production while achieving high discharge rates through the enhanced lithium ion transport pathways provided by the pores
3Ease of operation
If the particle size is reduced to improve low-temperature performance, then the charging capability is improved, but the compacted density is reduced
Solution Approach 1:
The patent introduces a porous structure with controlled pore sizes (0.5-2.0 μm) that facilitates rapid lithium ion diffusion to the particle interior, significantly improving low-temperature charging capability. Meanwhile, the overall particle size is maintained at larger dimensions, ensuring high compacted density when the electrode is assembled, thus resolving the contradiction between low-temperature performance and energy density
Data Source
AI summary
A negative electrode material includes a carbonaceous active material. Observed in a 80 μm×100 μm region of an SEM image, the carbonaceous active material includes carbonaceous particles with pores. A proportion of a quantity of the carbonaceous particles with a quantity of the pores of N≤2 in a total quantity of the carbonaceous particles in the 80 μm×100 μm region is ≤60%, and a proportion of a quantity of the carbonaceous particles with a quantity of the pores of 3≤N≤5 in the total quantity of carbonaceous particles in the 80 μm×100 μm region is ≤30%.