This document discusses lithium ion batteries with silicon anodes as an improvement over traditional graphite anodes. Silicon can store 10 times more lithium than graphite, offering higher energy density and capacity. However, silicon's large volume changes during charging cause cracking issues. Researchers are using silicon nanowires which can accommodate these changes without breaking. Silicon nanowire battery electrodes provide good performance with high capacity and long cycle life. Potential applications of lithium ion silicon anode batteries include consumer electronics, electric vehicles, and stationary energy storage.

1. LITHIUM ION - SILICON
ANODE BATTERIES
BY : ASHIMA GUPTA
ECE 2
12310102811

2. CONTENTS
1. INTRODUCTION
2. STANDARD LITHIUM BATTERY
3. SPECIFICATIONS AND WORKING OF LITHIUM ION BATTERY
4. NEED FOR SILICON ANODE
5. SILICON ANODE BATTERY
6. SILICON NANOWIRES
7. APPLICATION OF LI-ON SI ANODE BATTERY

3. INTRODUCTION
Lithium-ion batteries are common in consumer electronics. They are one of
the most popular types of rechargeable batteries for portable electronics, with
a high energy density, no memory effect, and only a slow loss of charge when
not in use. Beyond consumer electronics, LIBs are also growing in popularity for
military, electric vehicle and aerospace applications.
Thus with such wide applications, it was felt the need for the lithium ion battery
to have a higher capacity and longer cycle life and hence the lithium battery
with silicon anode was developed .
Further , silicon anode was used as silicon nanowires for better performance.

4. STANDARD LITHIUM ION BATTERIES
• A lithium-ion battery (sometimes Li-ion battery or LIB) is a member of a family
of rechargeable battery types in which lithium ions move from the negative
electrode to the positive electrode during discharge and back when
charging.
• Li-ion batteries use an intercalated lithium compound as one electrode
material, compared to the metallic lithium used in a non-rechargeable
lithium battery. The electrolyte which allows for ionic movement, and the two
electrodes are the consistent components of a lithium-ion cell.
• These are rechargeable batteries for portable electronics, with a high energy
density, no memory effect, and only a slow loss of charge when not in use. Li-ion
batteries provide lightweight, high energy density power sources for a
variety of devices. Lithium-ion batteries are in smart phones, laptops, most
other consumer electronics, and the newest electric cars.

5. SPECIFICATIONS AND WORKING
OF LITHIUM ION BATTERY
• Specific energy density: 360 to 900 kJ/kg
• Volumetric energy density: 900 to 1900 J/cm³
• Specific power density: 300 to 1500 W/kg
• During charging, an external electrical power source (the charging circuit) applies an over-voltage
(a higher voltage but of the same polarity) than that produced by the battery,
forcing the current to pass in the reverse direction. The lithium ions then migrate from the
positive to the negative electrode, where they become embedded in the porous electrode
material in a process known as intercalation.
• During discharge, lithium ions Li+ carry the current from the negative to the positive electrode,
through the non-aqueous electrolyte

6. NEED FOR SILICON ANODE
• In a lithium-ion battery, charge moves from the cathode to
the anode, a critical component for storing energy. There
was a need for developing rechargeable lithium batteries
with higher energy capacity and longer cycle life for
applications in portable electronic devices, electric vehicles
and implantable medical devices.
• Silicon is an attractive anode material for lithium batteries
because it has a low discharge potential and the highest
known theoretical charge capacity (4,200 mAh) .It absorbs
eight times the lithium of current designs, and has
maintained its greatly increased energy capacity.
• Silicon is a promising anode material to replace graphite for
high capacity lithium ion cells since its theoretical capacity
is ~10 times of graphite and it is an abundant element on
earth.
‘structured’ silicon in the form of
micron-dimension pillars

7. SILICON - ANODE BATTERY
• Design variations of the lithium-ion battery have been announced, in which
the traditional graphite anode is replaced by a silicon anode .It potentially
improves battery performance.
• Silicon stores ten times more lithium than graphite, offering increased energy
density. The large surface area increases the anode's power density,
allowing for fast charging and high current delivery. The anode was invented
at Stanford University in 2007.
• Silicon expands during charging and disintegrates after a small number of
cycles.

8. SILICON - NANOWIRES
• Initially , the people kind of gave up on using silicon because the capacity wasn't
high enough and the cycle life wasn't good enough. And it was just because of the
shape they were using. It was just too big, and they couldn't undergo the volume
changes. Silicon anodes had been dismissed because they tended to crack and
become unusable, because it swelled by 400% intercalating lithium during charging
. This degrades the performance of the battery. So researchers concentrated on
finding ways to use silicon, maintaining anode conductivity.
• Silicon nanowire battery electrodes circumvent these issues as they can
accommodate large strain without pulverization, provide good electronic contact
and conduction, and display short lithium insertion distances. The theoretical charge
capacity for silicon anodes was achieved and the discharge capacity close to 75%
of this maximum, with little fading during cycling was maintained.
• Silicon nanowires also provide enhanced mass support.
Silicon Nanowire

9. • A nanowire battery uses nanowires to increase the surface area of one or both
of its electrodes.
• The lithium is stored in a forest of tiny silicon nanowires, each with a diameter
one-thousandth the thickness of a sheet of paper. The nanowires inflate four
times their normal size as they soak up lithium. But, unlike other silicon shapes,
they do not fracture. The nanowires were grown on a stainless steel substrate,
providing an excellent electrical connection.
Fabrication of
graphene sheet
wrapped nano-Si

10. • One approach mixes silicon particles in a flexible polymer binder, adding
carbon to the mix to conduct electricity. Unfortunately the repeated swelling
and shrinking of silicon as it acquires and releases lithium ions eventually push
away the carbon particles. What’s needed is a flexible binder that can conduct
electricity by itself, without added carbon.
• Thus , a tailored polymer that conducts electricity and binds closely to lithium-storing
silicon particles, even as they expand to more than three times their
volume during charging and then shrink again during discharge was fabricated.
Anodes made from these conducting polymers have low-cost materials and
are compatible with standard lithium-battery manufacturing technology.
Silicon nanoparticles and graphene
Scaffolding combine to give two
patents pending.

11. • At left , the traditional approach to
composite anodes using silicon ( blue
spheres ) for higher energy capacity has a
polymer binder (light brown) plus added
particles of carbon to conduct electricity.
• Silicon swells and shrinks while acquiring
and releasing lithium ions. Repeated
swelling and shrinking eventually break
contacts among the conducting carbon
particles . At night ,the new Berkley Lab
polymer ( purple) is itself conductive and
continues to bind tightly to silicon particles
despite repeated swelling and shrinking.

12. APPLICATIONS OF LI-ON SI ANODE
BATTERIES
• Canonical announced on July 22, 2013, that its Ubuntu Edge smartphone would
contain a silicon-anode lithium-ion battery.
• Hybrid and Electric vehicle ( EV ) applications . Nissan is one such company involved
in the manufacturing.
• They could also be used in homes or offices to store electricity, generated by
rooftop solar panels.
• To power laptops, iPods, video cameras, cell phones, and countless other devices.
• “GEN3” lithium-ion battery : The GEN3 battery is largely based on Argonne’s
provisionally patented silicon-graphene battery anode process . CalBattery says
that it can produce the GEN3 battery in the United States at a cost reduction of 70
percent.

13. …THANK YOU…
* BY: ASHIMA GUPTA *
ROLL NO.: 12310102811
ECE-2