The electrochemical properties Essay


Lithium-ion batteries were foremost proposed by M.S. Whittingham ( Binghamton University ) , so at Exxon, in the seventiess. Whittingham used Ti ( II ) sulphide as the cathode and Li metal as the anode.

The electrochemical belongingss of the Li embolism in black lead were foremost discovered in 1980 by Rachid Yazami et Al. at the Grenoble Institute of Technology ( INPG ) and Gallic National Centre for Scientific Research ( CNRS ) in France

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Lithium batteries in which the anode is made from metallic Li airs terrible safety issues. As a consequence, lithium-ion batteries were developed in which the anode, like the cathode, is made of a stuff incorporating Li ions. In 1981

In 1983, Michael Thackeray, John Goodenough, and coworkers identified manganese spinel as a cathode stuff. ] Spinel showed great promise, since it is a low-priced stuff, has good electronic and lithium ion conduction, and possesses a 3-dimensional construction which gives it good structural stableness

In 2002, Yet-Ming Chiang and his group at MIT published a paper in which they showed a dramatic betterment in the public presentation of Li batteries by hiking the stuff ‘s conduction by doping it with aluminum, Nb and Zr, though at the clip, the exact mechanism doing the addition became the topic of a het argument.

In 2004, Chiang once more increased public presentation by using iron-phosphate atoms of less than 100nm in diameter. This miniaturized the atom denseness by about a hundredfold, increased the surface country of the electrode and improved the battery ‘s capacity and public presentation.


The three participants in the electrochemical reactions in a lithium-ion battery are the anode, cathode, and electrolyte.

Both the anode and cathode are stuffs into which and from which Li can migrate. The procedure of Li traveling into the anode or cathode is referred to asinterpolation( or embolism ) , and the contrary procedure, in which Li moves out of the anode or cathode is referred to asextraction( ordeintercalation) . When a lithium-based cell is dispatching, the Li is extracted from the anode and inserted into the cathode. When the cell is bear downing, the contrary procedure occurs: Li is extracted from the cathode and inserted into the anode.

During discharge, the anode of a conventional Li-ion cell is made from C, the cathode is a metal oxide, and the electrolyte is a Li salt in an organic dissolver.

The cathode half-reaction ( with bear downing being forwards ) is:

Advantages and disadvantages


  • Lithium-ion batteries can be formed into a broad assortment of forms and sizes so as to expeditiously make full available infinite in the devices they power.
  • Lithium-ion batteries are lighter than other energy-equivalent secondary batteries
  • Lithium-ion batteries do non endure from the memory consequence. They besides have a self-discharge rate of about 5-10 % per month.

Disadvantages of traditional Li-ion engineering

Shelf life

  • A disadvantage of lithium-ion cells lies in their comparatively haplessrhythm life: upon every ( rhenium ) charge, sedimentations form inside the electrolyte that inhibits Li ion conveyance, ensuing in the capacity of the cell to decrease.
  • Besides, high charge degrees and elevated temperatures ( whether ensuing from bear downing or being ambient ) hasten lasting capacity loss for lithium-ion batteries
  • At a 100 % charge degree, a typical Li-ion laptop battery that is full most of the clip at 25 & A ; deg ; C or 77 & A ; deg ; F will irreversibly lose about 20 % capacity per twelvemonth.

Internal opposition

The internal opposition of lithium-ion batteries is high compared to other rechargeable chemical sciences such as nickel-metal hydride and nickel-cadmium. It increases with both cycling and chronological age. Rising internal opposition causes the electromotive force at the terminuss to drop under burden, cut downing the maximal current that can be drawn from them. Finally they reach a point at which the battery can no longer run the equipment it is installed in for an equal period.

Safety demands

Li-ion batteries are non every bit lasting as nickel metal hydride or nickel-cadmium designs and can be highly unsafe if mistreated. They may detonate if overheated or if charged to an overly high electromotive force. Furthermore, they may be irreversibly damaged if dischargedbelowa certain electromotive force. To cut down these hazards, lithium-ion batteries by and large contain a little circuit that shuts down the battery when it is discharged below approximately 3V or charged above approximately 4.2. In normal usage, the battery is hence prevented from being profoundly discharged

Other safety characteristics are besides required for commercial lithium-ion batteries:

  • shut-down centrifuge ( for over temperature ) ,
  • tear-away check ( for internal force per unit area ) ,
  • blowhole ( force per unit area alleviation ) , and
  • Thermal interrupt ( over current/overcharging ) .

Specifications and design

A lithium-ion battery from a nomadic phone.

  • Specific energy denseness: 150 to 200 Wh/kg ( 540 to 720 kJ/kg )
  • Volumetric energy denseness: 250 to 530 Wh/l ( 900 to 1900 J/cm & A ; sup3 ; )
  • Specific power denseness: 300 to 1500 W/kg ( @ 20 seconds and 285 Wh/l )

Because lithium-ion batteries can hold a assortment of cathode and anode stuffs, the energy denseness and electromotive force vary consequently.

Charging process

Phase 1:

Apply bear downing current bound until the electromotive force bound per cell is reached.

Phase 2:

Apply maximal electromotive force per cell bound until the current diminutions below 3 % of rated charge current.

Phase 3:

Sporadically use a top-off charge about one time per 500 hours.

The charge clip is approximately three to five hours, depending upon the courser used. By and large, cell phone batteries can be charged at 1C and laptop-types at 0.8C, where C is the current that would dispatch the battery in one hr. Charging is normally stopped when the current goes below 0.03C but it can be left indefinitely depending on desired charging clip.

Top-off charging is recommended to be initiated when electromotive force goes below 4.05 V/cell.

For safety grounds it is recommended to remain within the makers stated electromotive force and current evaluations during both charge and discharge rhythms.

Guidelines for protracting lithium-ion battery life

  • Lithium-ion batteries should ne’er be depleted below their minimal electromotive force ( 2.4 to 2.8 V/cell, depending on chemical science ) . If a lithium-ion battery is stored with excessively low a charge, there is a hazard that the charge will drop below the low-voltage threshold, ensuing in an irrecoverable dead battery.
  • Lithium-ion batteries should be kept cool. Ideally they are stored in a icebox.
  • Aging will take its toll much faster at high temperatures.


Lithium-ion batteries can tear, light, or explode when exposed to high-temperature environments, e.g. in an country that is prone to protract direct sunshine. Short-circuiting a lithium-ion battery can do it to light or detonate and any effort to open or modify the shell or circuitry is unsafe. For this ground they usually contain safety devices that protect the cells from maltreatment.

Replacing the Li Co oxide cathode stuff in lithium-ion batteries with lithiated metal phosphate leads to longer rhythm and shelf life, improves safety, but lowers capacity.

Another option is to utilize a manganese oxide or Fe phosphate cathode.

A new category of high power cathode stuffs, Li Ni manganese Co ( NMC ) oxide has late been introduced that have a significantly higher temperature tolerance compared to lithium Co oxide


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