BATTERY

• John Goodenough: '"I was totally unable to anticipate what it would lead to," he said. "The engineers are pretty clever… they can do all kinds of things that you'd never even dreamed of doing."'
• Battery

  An electrical device consisting of one or more galvanic cells, with external connections provided to allow to power electrical devices
• Wet cell


  Battery where the electrolyte is a liquid, usually an aqueous salt
• Dry cell


  Battery where the electrolyte is in the form of a paste or a solid
• Primary batteries


  Cannot be returned to their original state by recharging
• Secondary batteries


  Can be returned to their original state by the application of an external electric current, which reverses the oxidation-reduction half cell reactions

  
• The first primary battery was developed in 1866 by Georges Leclanche and is called a Leclanche cell
• Leclanche cell


  Uses a zinc anode and a cathode made up of a mixture of carbon and manganese dioxide (s)

  
• Dry cell battery


  Leclanche battery modified to function by substituting an ammonium chloride paste for the aqueous ammonium chloride solution
• Alkaline battery

  Uses KOH as the electrolyte in the form of a paste or a gel, MnO2 mixed with graphite for the cathode, and a paste containing powdered zinc for the anode

  
• Alkaline battery is safe and comes in many sizes. It has no voltage drop, longer shelf life, and better performance in terms of power capability and stored energy

  
• Mercury battery


  Uses a zinc container as the anode (reducing agent) in a basic medium, with HgO as the oxidizing agent

  
• Silver battery

  Uses a zinc container as the anode (reducing agent) in a basic medium, with Ag2O as the oxidizing agent

  
• Disadvantages of mercury and silver batteries are the toxicity of discarded mercury and the high cost of silver
• Primary lithium battery


  Anode is lithium foil in a non-aqueous electrolyte, cathode is one of several metal oxides in which lithium ions lie between oxide layers

  
• Some pacemakers have a silver vanadium oxide (SVO; AgV2O5.5) cathode and can provide power (1.5 to 3.5 V) for several years, but at a low rate because energy storage is limited
• Secondary (rechargeable) battery


  Can be recharged by supplying electrical energy to reverse the cell reaction and re-form reactant

  
• Lead-acid battery

  Typical car battery has six cells connected in series, each cell contains two lead grids loaded with the electrode materials: high-surface-area (spongy) Pb in the anode and high-surface-area PbO2 in the cathode, immersed in an electrolyte solution of ~4.5 M H2SO4
• The main problems with the lead-acid battery are loss of capacity due to corrosion of the positive (Pb) grid and formation of large PbSO4 crystals that hinder recharging
• Lead-acid battery


  • Consists of six cells connected in series, each cell providing a potential of about 2 V
  • Contains two lead grids packed with high-surface-area (spongy) Pb in the anode and high-surface-area PbO2 in the cathode, immersed in a solution of 4.5 M H2SO4

  
• Problems with lead-acid battery

  • Loss of capacity due to corrosion of the positive (Pb) grid
  • Formation of large PbSO4 crystals that hinder recharging
  • Lead sulfate falls away from the electrodes due to mechanical shocks, battery can no longer be recharged and must be replaced
• Lead-acid battery discharge


  PbO2(s) + Pb(s) + 2H2SO4(aq) → 2PbSO4(s) + 2H2O(l), Ecell = 2.1 V

  
• Lead-acid battery recharge


  2PbSO4(s) + 2H2O(l) → PbO2(s) + Pb(s) + 2H2SO4(aq)

  
• Lead-acid batteries account for 88% of all lead consumed annually in the United States
• Consumption of Lead in India is in the range of 4 to 5 lakh tons per annum on average during 2008 to 2012, with 74% share in Batteries
• Nickel-cadmium (ni-cad) battery


  • Rechargeable, used in calculators and portable power tools
  • Susceptible to memory effect, where successive recharging results in shorter battery life

  
• Nickel-metal hydride (Ni-MH) battery

  • Anode half-reaction oxidizes hydrogen absorbed within a metal alloy (such as LaNi5) in a basic (KOH) electrolyte, while nickel(III) in the form of NiO(OH) is reduced at the cathode
  • Lightweight, high power, nontoxic, but discharges significantly during storage

  
• Lithium and lithium-ion batteries


  • Lighter weight and higher voltage (3-4 V) compared to nickel-based batteries
  • Lithium has a higher standard reduction potential and lower atomic weight than other metals
• Lithium battery


  1. Lithium metal anode, lithium salt (e.g. LiClO4) in organic solvent electrolyte, manganese dioxide cathode

  2. Oxidation of lithium at anode, reduction of MnO2 at cathode, Li+ ions migrate through electrolyte

  
• Lithium-ion battery


  • Graphite anode with lithium atoms inserted between carbon layers (LixC6), no lithium metal
  • Usual cathode is LiCoO2, electrolyte is lithium salt solution or solid-state polymer

  
• Lithium-ion batteries are used in watches, calculators, and other small consumer devices
• Li+ ions migration in lithium batteries

  1. Li+ ions migrate through the electrolyte from the anode to the cathode

  2. Electrons move from the anode to the cathode through the external circuit

  
• Lithium battery


  Uses a lithium metal anode
• Lithium-ion battery


  Uses a graphite anode that has lithium atoms inserted between its layers of carbon atoms (lithiated graphite, LixC6)

  
• Cathode in lithium-ion battery

  LiCoO2, a metal oxide that can incorporate Li+ ions into its structure

  
• Electrolyte in lithium-ion battery


  Either a solution of a lithium salt in an organic solvent or a solid-state polymer electrolyte
• Electrode reactions in lithium-ion battery

  1. Discharging: Anode - LixC6 → x Li+(soln) + 6 C(s) + x e-

  2. Cathode - Li(1-x)CoO2(s) + x Li+(soln) + x e- → LiCoO2(s)

  3. Charging: Reverse of discharging reactions

  
• Electrons flow through the circuit, while solvated Li+ ions flow from anode to cathode within the cell
• Negative electrode materials


  • Pure metal
  • Alloy
  • Hydrogen
• Negative electrode in lead-acid cell

  • Pure lead