smart multifunctional fluids for lithium ion batteries: …

Lithium-ion batteries are attractive power sources in the consumer electronics market and are currently actively developing batteries for road transport.
However, the problem of safety and reliability needs to be in large-
The scale of these batteries is absorbed.
Recently, material with anti-mechanical abuse capability has been significantly developed and evaluated with the aim of strengthening the battery to prevent perforation during collision.
Most of the work on the mechanical safety of the battery is concentrated on the external packaging of the battery, with little attention to the closed electrolyte.
We report intelligent multi-functional fluid, which is both a highly conductive electrolyte for lithium-ion batteries and an inherent mechanical protector for lithium-ion batteries.
These fluids exhibit a shear thickening effect under pressure or impact, resulting in excellent crushing resistance.
In addition, these fluids show higher ionic conductivity and comparable redox stability windows than commercial liquid electrolyte.
Composite electrolyte is synthesized by mixing gas phase silica particles with different weight ratios (S5505, Sigma-Aldrich)
In a commercial electrolyte consisting of ethylene carbonate/Diester carbonate (EC/DMC)(
Volume ratio 1:1)with 1u2005M LiPF (Jiangsu Guotai)in an argon-
Box full of gloves
Stable suspension of EC/DMC/LiPF with 63 wt.
% SiO, EC/DMC/LiPF with 9. 1 wt.
EC/DMC/LiPF for % SiO and 10. 7 wt.
Get % SiO and save it in the glove box until ready to use.
Before use, dry silica particles by vacuum suction.
The gas phase method silica primary particles are inevitably fused into large aggregates that cannot be cut and destroyed.
Suspended solids are transparent and do not show visual evidence of increased phase separation, precipitation or turbidity over a long period of time.
This phenomenon was also observed by other groups.
Using coin-plating tests on battery performance at different current densities at room temperature
Half cell type (2032 type).
These batteries are in ar-
Filling glove box for commercial LiFePO and graphite electrodes (Massachusetts Institute of Technology
The self-made LiCoO electrode is used as the working electrode respectively;
Use Li metal as an anti-electrode;
Porous Polyethylene (Celgard 2500)
Used as a separator;
Composite solution of synthesis (
The exposed EC/DMC/LiPF, EC/DMC/LiPF were 6. 3 wt.
% SiO, EC/DMC/LiPF with 9. 1 wt.
EC/DMC/LiPF for % SiO and 10. 7 wt. % SiO)
Used as electrolyte, respectively.
LiCoO electrode was prepared from the active material (LiCoO)
Carbon Black and poly-difluoride adhesive (PVDF, Sigma-Aldrich)
The weight ratio is 8: 1.
The coated electrode dries for 20 hours at 100 °c and then rolls
Press before use.
The thickness of the LiCoO electrode is about 0. 1u2005mm.
The battery cycles in the voltage range of 2. 2–3. 8u2005V (versus Li/Li)
Half cells of LiFePO 3. 0–4. 3u2005V (versus Li/Li)
For LiCoO half cells, 0. 01–1. 5u2005V (versus Li/Li)
Graphite semi-battery.
Using a chemical workstation to measure the impedance change of the battery before and after impact (CHI604C).
Specifically, for the analysis of ion conductivity, the electrical impedance spectrum (EIS)
The chemical workstation was used to test the bare electrolyte and electrolyte with different SiO weight ratios in two platinum electrode conductivity batteries in the glove box (CHI604C)
Within the frequency range from 1 hz to 0. 1u2005MHz.
The ion conductivity of all samples is calculated based on the peak of the straight line curve obtained from the impedance data and the intercept of the real axis. The coin-type cells (2032 type)
Also used for impact testing.
The LiFePO electrode, the LiCoO electrode and the graphite electrode are assembled into three semi-batteries respectively.
Fill the glove box with the electrolyte: exposed EC/DMC/LiPF, EC/DMC/LiPF and 6. 3 wt.
% SiO, EC/DMC/LiPF with 9. 1 wt.
% SiO and EC/DMC/LiPF and 10. 7 wt. % SiO.
After assembling the batteries, remove them from the glove box, and then place them in the oven at 40 °c for 4 hours to allow the electrolyte to soak fully into the separator and electrode.
Impact test using slide device ()
Stainless steel truncated cone is allowed (140u2005g)
Slide from a certain height to hit the battery ()
When they were discharged
Collect the discharge curve using the NEWARE battery tester and measure the impact force using a force sensor.
Although the difference in the composition of the battery resulted in different degrees of impact tolerance, neither the bare electrolyte nor the composite electrolyte with 6 were available. 3 wt. % SiO (
Show the effect of shear thinning)
Provide better protection for the battery ().
Composite electrolyte of 9. 1 wt. % SiO and 10. 7 wt. % SiO (
With shear thickening effect)
However, they were found to provide additional protection.
Several parallel experiments were conducted on these three cells to obtain repeatable results.