SEC 598 – PV SYSTEMS ENGINEERINGProject -1

A Brief Study on Lithium-Ion Battery Technology For Large Scale Residential Systems

- GOVINDARAJASEKHAR SINGU

Contents Introduction and Purpose

Battery Science & Electrochemistry

Power & Energy Density

Construction & Manufacturing Technologies

SWOT Analysis

Conclusion

Introduction With a tenfold increase in the market for small solar power storage systems expected over the next three years, it is important that Second Solar aggressively develop and produce battery-supported photovoltaic (PV) systems for residential applications at large deployment scales to capitalize on this opportunity. Lithium-ion batteries have been selected for a suitability analysis, and are advocated by the others to serve as the preferred battery choice for these residential systems.

Battery Science & ElectrochemistryThe smallest working unit in a battery is the electrochemical cell, consisting of a cathode and an anode separated and connected by an electrolyte.

The electrolyte conducts ions but is an insulator to electrons. In a charged state, the anode contains a high concentration of intercalated lithium while the cathode is depleted of lithium.

During the discharge, a lithium ion leaves the anode and migrates through the electrolyte to the cathode.

Contd.. The chemical reaction of lithium-cobalt battery at anode and cathode is,

Cathode:

Anode:

In a lithium-ion battery the lithium ions are transported to and from the positive or negative electrodes by oxidizing the transition metal, cobalt (Co), in Li1-xCoO2 from Co3+ to Co4+ during charge, and reduced from Co4+ to Co3+ during discharge.

Cathode Materials: Cobalt, Manganese, Phosphate, Nickel-cobalt-manganese

Anode Materials: Graphite and Copper foils.

Power & Energy Density Power Density (W/L) – The maximum available power per unit volume

P = Voltage * Ampere-hours

Energy Density (Wh/L) – The nominal battery energy per unit volume.

E = Power (Wh) /mass

For residential energy storage systems Nickel-Cobalt-Manganese-Oxide and Nickel-Cobalt- Aluminum-Oxide are considered because of their higher energy and power density.

Contd.. Manufacturer’s specifications of NMC battery,

Construction & Manufacturing Tech’s

Lithium ion cells are available in three different shapes they are: cylindrical, prismatic, pouch cells. The figure is shown below,

Contd.. General manufacturing procedure of li-ion batteries is,

Contd…Currently existing technologies to construct and manufacture a lithium ion cell, they are,

Magnetron Sputtering - a target material is bombarded with microwaves during discharge, which ionizes and vaporizes the target material.

Aerosol Deposition - an electrolyte solution is aerosolized and fed to an extremely hot oxygen-hydrogen flame which deposits a layer of “glass soot” on a chosen substrate or electrode material.

Contd.. Pulsed Laser Deposition – It is an accurate and reliable way to deposit extremely thin (down to 1.2 nm thick) films on top of a chosen substrate.

Assembly Techniques:

Bolt Joining (Cylindrical), Ultrasonic/Tab welding(Pouch), Projected welding(Prismatic/Cylindrical)

SWOT Analysis Strengths – Light weight than Lead Acid batteries

- Higher Energy density

- Long Lasting

Weaknesses – Need for Battery Management Systems

- Expensive than other battery technologies

Opportunities – Li-ion batteries may become cheaper as electric vehicle industry matures.

- Global market of PV Systems coupled with power systems is expected to increase over next three years.

Threats – Emerging battery technologies

- Resource limitations (Recycling process is complicated for Li-ion batteries)

Conclusion Based on the study it is concluded that Li-ion can store large amount of energy for a long time than any other existing battery technology.

It has low discharge rate and able to withstand cold weather conditions which is mainly suitable for residential energy storage systems.

It can be dispose easily and recyclable too which reduces environmental hazards.

Thank You