Secondary Battery Negative Electrode Low Temperature Durability
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Solution Overview
Problem
Existing secondary battery technologies face challenges in achieving both low temperature regeneration characteristics and high temperature durability, with previous methods either compromising on one or the other due to issues related to reaction area increase and adhesion strength.
Innovation Solution
A secondary battery design featuring a negative electrode active material with graphite of 10 nm or more crystalline size and interlayer distance of 0.3356 to 0.3360 nm, combined with a rubber-based binding material of 120 to 250 nm average primary particle diameter, and a specific pore capacity, applied through pressure and carbonaceous material filling to optimize electrode structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If styrene-butadiene rubber with small particle diameter (100 nm or less) is used to improve adhesion strength, then adhesion strength is improved, but low temperature regeneration characteristics deteriorate
Solution Approach 1:
The invention optimizes the particle size parameter of the rubber-based binding material to a specific range (120 to 250 nm), which is larger than conventional small particle diameters (100 nm or less). This parameter change allows the binding material to form an effective network structure for adhesion while preventing excessive intrusion into graphite pores, thereby maintaining low temperature regeneration characteristics.
Solution Approach 2:
The invention creates different local structures: the rubber-based binding material forms a continuous network structure in the spaces between graphite particles for adhesion, while the graphite particles themselves maintain their internal pore structure for low temperature reaction. This local differentiation allows simultaneous achievement of strong adhesion and good low temperature regeneration.
Data Source
AI summary
A secondary battery according to one aspect of the present disclosure includes a negative electrode which includes a negative electrode core and a negative electrode active material layer provided on at least one surface of the negative electrode core. In this secondary battery, the negative electrode active material layer includes a negative electrode active material which contains graphite having a crystalline size of 10 nm or more and an interlayer distance d002 of 0.3356 to 0.3360 nm and a rubber-based binding material having an average primary particle diameter of 120 to 250 nm, the negative electrode active material has a pore capacity of 0.5 ml/g or less at a pore diameter of 0.2 to 1 μm measured by a mercury porosimeter, and the rate of the average primary particle diameter of the rubber-based binding material to the pore capacity of the negative electrode active material is 1.15 to 1.70 g/m2.