Page 121 - Toucpad robotics C11

Lithium-ion (Li-ion) Batteries

Electrolyte
Porous
Separator
Electrolyte

ANODE (–)

Lithium-carbon
(Graphite)
CATHODE (+)
Lithium ION
Lithium Metal
Oxide

Lithium-ion batteries are a family of rechargeable batteries that have become ubiquitous in portable electronic devices
(like smartphones and laptops) and are increasingly dominant in advanced robotics, electric vehicles, and renewable
energy storage.

Description and Working Principle
A Lithium-ion battery generates electricity through the movement of lithium ions between a positive electrode
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(cathode) and a negative electrode (anode) through an electrolyte solution.
During discharge (when the battery is powering the robot), lithium ions move from the negative electrode through
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the electrolyte to the positive electrode, and electrons flow through the external circuit, creating electric current.
During charge (when the battery is being recharged), an external power source forces the lithium ions back from the
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positive electrode to the negative electrode, reversing the process and storing energy.
They do not contain free lithium metal; rather, the lithium ions are embedded within the electrode materials.
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Characteristics

High Energy Density: Can store a large amount of electrical energy relative to their weight and volume. This means
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a Lithium-ion battery can provide more power for a given size compared to many other battery types.
High Power Density: Can deliver high amounts of current rapidly, which is essential for powerful motors and fast
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movements.
Low Self-Discharge Rate: They retain their charge for a relatively long time when not in use.
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No Memory Effect: Unlike some older battery technologies, Lithium-ion batteries do not need to be fully discharged
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before recharging to maintain their capacity. They can be “top-up charged” frequently without degrading performance.
Various Chemistries: There are several sub-types (e.g., Lithium Cobalt Oxide, Lithium Manganese Oxide, Lithium Iron
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Phosphate) each with slightly different characteristics regarding energy density, power output, safety, and lifespan.

Applications in Robotics
Mobile Robots and Drones: Ideal for robotic vacuum cleaners, delivery drones, humanoid robots, and inspection
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robots due to their lightweight and high energy density.
Autonomous Vehicles: Used as the primary power source in many electric and hybrid autonomous cars.
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Industrial Robots (Battery-Powered AGVs/AMRs): Powering autonomous mobile robots in warehouses and
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factories where high uptime and energy efficiency are critical.
Advanced Prosthetics: Enabling extended operation of sophisticated robotic limbs.
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Electrical and Control Systems