HQ-1150 pages

Technical Data

October 2012

3M™ Battery Electrolyte HQ-115
Introduction
3M™ Battery Electrolyte HQ-115 (lithium bis-trifluoromethanesulfonimide) is a high purity electrolyte salt ideal for use
in rechargeable lithium ion and lithium polymer batteries, as well as primary lithium batteries. Electrolyte HQ-115 is
widely used as an electrolyte additive at low concentrations in LiPF6-based electrolytes for enhancing the performance
and life of high capacity rechargeable lithium ion batteries. Because of its high conductivity, solubility and thermal
stability, electrolyte HQ-115 is also an ideal supporting electrolyte salt for rechargeable lithium polymer and primary
lithium battery systems.
3M Battery Electrolyte HQ-115 is manufactured to meet the strict purity requirements of the lithium battery industry.
Electrolyte HQ-115 is available in both dry and aqueous versions.

Advantages
Longer Battery Life
Battery performance can degrade rapidly when cells are exposed to high temperatures that are typical in consumer batteries
and even more common in large format transportation or grid storage batteries. The use of electrolyte HQ-115 as an
additive in high capacity lithium ion batteries has been shown to provide a 10% increase in capacity retention after only
300 cycles at 50°C. Used at a concentration of 2-5 wt%, electrolyte HQ-115 thus provides a cost effective method to
improve battery performance when cycled at high temperature. Studies have shown that there is a synergy between
electrolyte HQ-115 and VC (vinylene carbonate) and a combination of these two additives (utilizing 1-2 wt% VC)
generally works best for improving capacity retention and reducing the build-up of impedance in cells at elevated
temperatures.
Reduced Gas Generation
Generation of gases during high temperature cycling or storage can cause undesirable venting in lithium ion wound cells
and swelling in pouch or prismatic cells. The use of electrolyte HQ-115 in low concentrations can create a protective layer
at the electrode-electrolyte interface (SEI) and thereby suppress parasitic electrochemical reactions that can lead to the
generation of these gases. Consequently, gas generation and the resulting venting and swelling of cells can be reduced
through the use of electrolyte HQ-115.
Cell Impedance Control and Safety
The protective layers formed at the SEI when using electrolyte HQ-115 have been shown to provide a stabilizing effect on
cell impedance. As a result, the buildup of impedance (or resistance) within the cell during cycling or storage is reduced
and satisfactory rate capability can be maintained for longer periods through the use of low levels of electrolyte HQ-115,
thus extending the useful life of the battery. In certain types of lithium ion cells equipped with single layer polyethylene
separators, soft shorts can develop under high temperature storage (or float) conditions. This can limit the useful life of the
battery and is also a safety concern. Without electrolyte HQ-115, charged cells stored at 60°C have been seen to develop
soft shorts after approximately 20 days of storage. Adding electrolyte HQ-115 as an additive has been shown to eliminate
the incidents of shorting over at least a 35 day period, thus improving cell safety and extending the life of the cells. As a
result, electrolyte HQ-115 can enable improved cell designs that are more thermally stable and lower in cost.

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