Active Grid Technology

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Active Grid Technology

• Electro-Chemical Energy Storage System
  Enhancement through Ultrasound

Silver-Zinc Battery Enhancements
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AGT Application to Silver-Zinc Cells

• AGT significantly alters the chemical process
  within lead-acid cells.
• What can AGT do for a silver-zinc cell?
• Or any other zinc-based chemistry?
• Let us start by addressing one of the current
  problems with these types of cells.

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Zinc Electrode During Charge/Discharge

• During the discharge, zinc is converted to zinc
  oxide.
• Some of the zinc oxide dissolves in the
  electrolyte and is named zincate.
• During the charge, zinc oxide is converted back
  to zinc.
• Zincate also comes out of solution and re-plates
  on the electrode.

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Zincate Re-plating

• Problem If all zincate does not come out of
  solution during charge, active material is lost
  reducing capacity
• Problem When the zincate comes out of solution
  during the charge it does not re-plate where it
  originally came from
• This is shape change
• Zinc deposits preferentially towards the center
  of the electrode and closer to the bottom
• It plates out where there are
• High concentrations.
• Sharp edges.
• Protuberances.

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Objective Reduce Shape Change

• Distributing the zinc oxide sites more uniformly
  on the electrodes, during the discharge, reduces
  shape change and non-uniform current densities
• Thus reducing cell imbalances and dendrite
  treeing during overcharge event.
• This also allows more zincate to come out of
  solution during each charge due to the increased
  nucleation sites generated during the discharge
• Minimizing the zinc electrode loss during
  cycling.
• The manufacturer can reduce the excess zinc used.

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How Does AGT Affect Shape Change?

• AGT puts the disorder back into the system
• During the discharge, the zinc-to-zinc oxide
  conversion sites are more evenly distributed
  throughout the electrode.
• During the charge, the conversion of zinc oxide
  to zinc is greatly enhanced
• When zincate comes out of solution it will see
  many more nucleation sites and therefore it will
  plate out uniformly vice at normal preferential
  locations
• The zinc-oxide will not be given a chance to
  settle in during the discharge or charge
• Zinc will plate out uniformly across the entire
  electrode area during every charge.

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How Can We Be Sure AGT Uniformly Distributes the
Zinc back onto the Plate?

• Testing is the only way to be completely sure,
  but
• AGT is based on ultrasonic energy and it is
  used in several industries to address problems.
  It is used for
• Cleaning, sterilization, Bonding dissimilar
  metals, Melting metals, Prevention of algae
  growth, Non-destructive testing, Imagining,
  Sonar, Liposuction, Cell destruction, Tumor
  removal, Kidney stone reduction/elimination, Drug
  injection systems, etc..
• AGT substantially reduces the three main causes
  of uneven distribution.

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AGT Reduces the Three Main Causes of Uneven
Distribution

• High concentrations AGT agitates the
  electrolyte, thus reducing regions of high
  concentration and thus reducing large
  concentration gradients.
• Sharp edges AGT reduces the sharp edges caused
  by cycling. It overcomes the sharp edges
  introduced in manufacturing process. The
  electrode will be much smoother. Its topical
  morphology will be transformed.
• Protuberances AGT minimizes the size of
  discontinuities, thus reducing their adverse
  effects.

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Even Distribution
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How Does AGT Eliminate Dendrite Treeing?

• The smooth, uniform distribution of zinc on the
  electrode minimizes dendrite treeing.
• Uniform current density throughout the electrode
  also helps.
• In addition, the lower internal impedance keeps
  the voltages lower during the charge, thus
  reducing the restrictions during the charge.

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Dendrite Trees Are Crystal Structures

• When dendrite crystals grow, they pass through
  similar structures
• The trunk of the tree (fern) is of most interest
  to AGT. Envision it as a cantilever beam.
• As the crystals grow during an overcharge event,
  they branch out toward the opposite electrode
• If this growth continues, the needle-like
  structures penetrate the separator system.
• This can cause a catastrophic event.

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Crystal Dendrites Can Pierce the Separator
Membrane
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AGT Exploits the Known Crystal Structure and
Prevent Dendrite Treeing

• Crystal structures are susceptible to a resonant
  frequency
• AGT directs energy, in ultrasonic form, to
  regions where the crystals form
• The frequency of the energy targets the resonant
  frequency of the tree trunk
• The AGT energy barrier prevents the zinc-oxide
  formations from settling in and it prevents the
  tree trunk from branching off into the
  electrolyte
• The energy required to keep the zinc oxides in
  disarray is minimal
• The energy required to prevent branching is
  minimal

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AGT Energy Barrier Prevents the Trunk from
Branching Off
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Current Status and Next Step

• Have conducted two rounds of ST level initial
  testing with very positive results
• Have received EU patent protection in the UK,
  France, Sweden, Spain, Czech Republic, Ireland,
  Germany, Netherlands and Switzerland.
• Have applied for protections in the U.S. and
  Canada

• Looking for optimal collaboration and/or
  licensing relationship with interested battery
  vendor to complete RD phase and move AGT into
  the marketplace