UBE announced that we attend the 24th Annual Advanced Automotive Battery Conference (AABC) on 10 – 12 December 2024.

We reported on “Polyimide Binder for Lithium-ion Battery”, which is applying water solvent, at the poster session. Data of NMP solvent polyimide binder is shown as below contents. The data has been obtained that polyimide binder are effective for Si-system materials.

Applicability of Polyimide binder for Si-system anode

Trend towards high capacity and high input/output.

The use of Si-based active materials with large theoretical capacity is actively being studied.
Issues: pulverization and cycle degradation due to large expansion and contraction.

Requirements for binders:

It is assumed that it is important to have a high “breaking energy,“
which is an indicator of the durability until the binder breaks
Breaking energy MJ/㎥ = S-S Curve Square
・High breaking energy = Potential applicable of Polyimide binder

High strength Polyimide binder for Lithium-ion battery
(NMP solvent)

High strength Polyimide binder for Lithium-ion battery (NMP solvent)

・Developed an NMP-based polyimide binder with enhanced strength by improving UPIA®-AT-1001
・Potential applicability to pure Si, which has an even higher capacity than SiO

Serial Coating Trial and Charge-Discharge Evaluation of
Si Electrodes Using Newly Developed Polyimide Binder
(NMP Solvent)

In roll-to-roll coating electrode, no occurrence of curling and electrodes with good coat ability were obtained.

Composition of Negative Electrode

Si(3000mAh/g) wt%	Binder wt%	AB wt%
72.0	18.0	10.0

How to make Negative Electrode

Charge-discharge evaluation of Si Electrodes Using Newly Developed Polyimide Binder(NMP Solvent)

Fabrication of full-cell using prototype Si electrode

・Fabricated a full cell to verify the performance of the prototype electrode.
・Fabricated a full cell using graphite as a comparison electrode.
・Monitored the internal state of the battery and compared performance when applying the current load that flows when the drone moves up, down, left, right, or hovering.

　　

		Silicon Electrode	Cf. Graphite Electrode
Anode		Silicon （3.5 mAh/㎠)	Artificial Graphite （3.5 mAh/㎠)
Cathode		Ternary system （3.0 mAh/㎠)	Ternary system （3.0 mAh/㎠)
Separator		Ceramic coated separator(19µm)
Electrolyte		1M LiPF6 EC:DEC (1:1)＋1wt%VC
Cell Dimension	Thickness	5.5±3 mm
	Length	188±2 mm
	Width (Inc. Tab)	317±2 mm
Weigh		442 g	370 g
Rated Capacity		22 Ah (@25℃)	16 Ah (@25℃)

Doron simulation using prototype Si electrode

Output confirmation during drone flight

【Voltage during flight and current profile】

Current value during flight / C-rate	Max current value /C-rate	Battery Temperature	Flight time
15-23 A 2.9-4.5CA	41.5 A 8.1CA	33℃	15.6min

Measure the current value during flight and calculate the current value required for movement in all directions and hovering.

Silicon anode battery using polyimide binder vs. commercial graphite single battery

⇒ Confirmed the superiority of polyimide binder

【Discharge characteristics of Si battery】

【Discharge characteristics of Si battery】