Materials for Energy Fuel Cells and Redox Batteries Andy Creeth, CTO January 2015

© ACAL Energy Ltd Energy Storage – Hydrogen as Energy Vector Energy storage Eg Redox Battery Return to Grid Energy conversion Electrolysis Hydrogen Energy vector Renewables

© ACAL Energy Ltd Fuel and engines 19 th Century 20 th Century 21 st Century Fuel from non-renewable fossil fuel Hydrogen as Energy Vector from renewable source

© ACAL Energy Ltd

5 Commercial

© ACAL Energy Ltd Fuel Cell Markets Transport Power Supply – at multiple scales Remote/back-up power Chp Portable Hydrogen supply needed

© ACAL Energy Ltd Who are ACAL Energy? British based clean energy chemical/electrochemical company Designed the first low cost, high performance hydrogen fuel cell for both automotive and stationary power markets 75% platinum replaced by low cost liquid catalyst solution – polyoxometallate Other storage applications – batteries, electrolysers ACAL Energy will license its technology to OEM’s and Tier 1’s while retaining ownership & distribution of the “secret sauce” chemical compound Core Technology proven. Now ready for customer and supply chain product development Projects/advanced discussions with major automotive OEM’s & leading stationary power providers, plus some supply chain partners £18m raised to date from leading international tech investors including:

© ACAL Energy Ltd Conventional PEM Fuel Cell Weaknesses MembraneCathode  Too Costly – got to compete with IC Materials - Pt System complexity  Poor durability. Membrane and catalyst suffer degradation.  Auto companies challenge - low Pt and acceptable durability ‘Platinum agglomeration is key reliability issue’ - Japanese Auto Maker 8

© ACAL Energy Ltd Materials for Standard PEM Fuel Cell Ultra-low precious metal content catalyst materials Currently 30 g/car. Need to reach g/car Well-resourced – not certain that target is achievable – compromise with durability Membrane Electrolytes Need to operate at 95 C and above – a drying atmosphere Well-resourced Hydrogen tanks 700 bar Carbon fibre-reinforced plastic Currently too expensive

© ACAL Energy Ltd  Polymer Electrolyte Membrane (PEM)-type  FlowCath technology replaces air/Pt electrode by soluble catalyst/mediator  Catalyst reduces oxygen to oxidize mediator in regenerator  Mediator reduced in cell to make electricity  Major cost & durability advantages ACAL Energy FlowCath ® Concept Liquid Phase Oxygen Catalyst/Mediator to Drive Fuel Cell

© ACAL Energy Ltd  Polyoxometallate System  Highly Stable - Thermodynamically stable  Inorganic self- associating structure  V-based redox process  Recent developments  Catalysis at higher redox potential – ie higher voltage in cell  Potential for further increase in redox potential – not limited by Pt reaction Catalyst Development 11

© ACAL Energy Ltd World Leading Performance in Auto Cycle Durability Testing Test protocol supplied by Japanese auto maker, designed to be a accelerated test Includes anode air purge every ~ 40 minutes; 80 C no applied pressure 10,000 h achieved – standard PEM not achieved more than 5000 h Over 8000 hours and over 12,000 anode air purge cycles with no change in performance h

© ACAL Energy Ltd Inherently more durable Catalyst is thermodynamically stable Oxygen reduction occurs away from cell, so no contribution of reactive species to damage in the cell Oxygen reduction occurs in Regenerator

© ACAL Energy Ltd ACAL Energy New Materials Interests New catalyst materials and formulation ingredients Foam generation and removal Porous electrode materials Engineering concepts Manufacturing routes Membrane optimisation

© ACAL Energy Ltd Energy Storage Cost-competitive technologies Life cycle cost analysis shows competitiveness of redox battery and electrolyser/fuel cell combination Source: Economic Analysis of Large-ScaleHydrogen Storage for Renewable Utility Applications, S Schoenung, Sandia National Laboratories Battery costs Fuel Cell costs Electrolyser/Fuel Cell combination have cheaper lifetime costs than Batteries – cheaper energy store

© ACAL Energy Ltd Overview of Redox Batteries Convert chemical energy to electrical energy and back again High round-trip efficiency – target 75% Immediate response Consist of conversion unit and chemical storage of energy Chemical storage in flow batteries is outside conversion unit Conversion unit sized for power input/output Storage unit sized for energy storage Energy Storage Unit Energy Conversion Unit Energy storage and conversion are sized and costed separately

© ACAL Energy Ltd Redox Batteries Materials Challenges Cost of storage materials – cheaper than Li ion batteries Low power density –cf ACAL Energy fuel cell Selective membranes to prevent crossover Porous electrode materials Optimisation of electrolytes for electrode kinetics Opportunity to improve power density by factor 5-10 Energy Storage Unit Energy Conversion Unit Energy storage and conversion are sized and costed separately

© ACAL Energy Ltd Conclusions Hydrogen Fuel Cells commercial development underway Opportunity for CO2 reduction and to move away from fossil fuels for transport Hydrogen as energy vector Materials needs Oxygen reduction (and evolution) catalysts Robust and selective membranes Foam management Porous electrode materials Redox batteries – option for grid storage; opportunity for lower cost high power output conversion units. Need: Selective membranes Porous electrode materials Electrolyte optimisation