Batteries for energy storage in industry Flashcards
What types of electrical energy storage systems are available?
- Mechanical
- Thermal
- Chemical
- Electro-chemical
- Electrical
What are examples of mechanical storage?
- PHS
- CAES
- LAES (liquid air)
- Flywheels
What are examples of thermal storage?
- Thermo-chemical
- Sensible thermal
- Latent thermal
What are examples of chemical storage?
- Hydrogen storage
- SNG
What are examples of electro-chemical storage?
- Li-ion
- Lead Acid
- NaS (Sodium-Sulphur)
- Redox flow
What are examples of electrical storage?
Supercapacitors
Describe the basic principle of a battery.
The aim is using electrons to transform a component to another component in order to produce or to store electricity. Use of a reduction-oxidation reaction to convert chemical energy into electrical energy (discharge). Rechargeable batteries, called secondary batteries, can perform the inverse process to recover their initial state (charge).
What is the oxidation process?
Production of electrons
What is the reduction process?
Consumption of electrons
What are main advantages of batteries?
- Great energy density
- High efficiency
- Low self discharge
What are primary battery cells?
Single use chemistry => non-reversible chemical reaction, high energy density
(Zinc-Carbon, Alkaline)
What are secondary battery cells?
Reversible chemistry, reaction can be reversed
(Li-Ion, Lead Acid)
What is the state of charge?
Amount of energy remaining as percentage of actual storage capacity
What is the depth of discharge?
Percentage of energy taken from battery
What is EoL?
End of Life: When the remaining is typically 80/70/60% of its initial capacity.
What is the State of Health?
Present capacity compared to the initial capacity (100%)
What is Energy to Power ratio?
E2P is the ratio between installed energy and installed power
What is the C-rate?
Expression of (dis)charge current of battery in order to normalize against battery capacity
1C = discharge full capacity in 1 hour
C2 = discharge full capacity in 2 hours
2C = discharge full capacity in 0.5 hour
How does a Lead Acid Battery works?
During discharge, each electrode is converted to lead sulfate (PbSO4) =>Sulfuric acid is consumed from electrolyte. When recharging the lead sulfate is converted back to sulfuric acid, leaving a layer of lead dioxide on the cathode and pure lead on the anode.
What are main advantages of lead acid batteries?
- Very Low Cost
- Well established recycling
- Mature and reliable (140 years of development)
- Robust
- Tolerant to overcharging
- Low self-discharge, 5-10% per month
- Suitable for power and energy
What are main disadvantages of lead acid batteries?
- Danger of overheating, temperature sensitive
- Low energy density compared to Li-ion
- Low cycle life
- Lots of maintenance
- Not environmentally friendly
What is the working principle of Lithium-Ion batteries?
While charging, Li-ions move from the cathode to the anode and are intercalated into the graphite layer. During discharge the Li-ions move back via the electrolyte to the cathode
What are main advantages of Li-ion batteries?
- High round trip efficiency 90-96%
- High energy and power density
- Low self-discharge (5% per month)
- Low maintenance
- Long cycle and calendar life
- Lots of research, price continuously decreasing
What are the main disadvantages of Li-Ion?
- No inherent safety
- More complex BMS
- High energy cost (compared to Lead acid)
How does Sodium-Sulfur batteries work?
The system has to be hot (> 300*) to allow the electron flow during charge or discharge (independent heaters required). Liquid positive electrode of Sulfur and liquid negative electrode of Sodium.
What are the main advantages of NaS?
- Very low energy cost
- High power and energy density
- High cycle and calendar life
What are main disadvantages of NaS?
- High power cost
- So more suitable for energy applications’
- Must be kept at high temperatures
- Not that safe (Violent reactions)
How does Redox flow batteries work?
Two electrolytes, acting as liquid energy carriers, are pumped simultaneously through the two half-cells of the reaction cell separated by a membrane.
What are the main advantages of Redox Flow?
- Low energy cost
- Energy and power scalable independently
- High cycles and calendar life
- 100% DoD possible
What are the main disadvantages of Redox Flow?
- Leakage caused by acidic fluids, large amounts of acid
- Requires pumps, valves => maintenance
- Low energy density (but in development for decreasing)
How can a battery be divided?
Cell => Module => Rack/stack => containerized battery
System = multiple modules/racks + BMS
What does PCS stands for?
Power Conversion System
