1. Batteries and capacitors
Guoqing Ning

2. Batteries Capacitors Content Types NiH battery Li ion batteries
Suppercapacitor
Li-ion capacitor

3. Batteries

4. Types of batteries Primary cells or non-rechargeable batteries
Alkaline battery, Aluminium–air battery, Lithium battery, Dry cell, Nickel oxyhydroxide氢氧化物 battery, Zinc–air battery, Zinc–carbon battery
Secondary cells or rechargeable batteries
Lead–acid battery, Lithium-ion battery, Nickel–cadmium镉battery, Nickel hydrogen battery, Nickel–iron battery, Sodium-ion battery

5. Primary cells zinc–carbon battery -- "zinc–manganese" cell
the overall reaction

6. Primary cells - Alkaline battery
From left to right: C, AA, AAA, N, and 9V alkaline batteries

7. Primary cells - Alkaline battery
Alkaline batteries are a type of primary battery dependent upon the reaction between zinc and manganese(IV) oxide (Zn/MnO2). A rechargeable alkaline battery allows reuse of specially designed cells.
Compared with zinc-carbon batteries of the zinc chloride types, alkaline batteries have a higher energy density and longer shelf- life, with the same voltage. The alkaline battery gets its name because it has an alkaline electrolyte of potassium hydroxide, instead of the acidic ammonium chloride or zinc chloride electrolyte of the zinc-carbon batteries.
Alkaline batteries account for 80% of manufactured batteries in the US and over 10 billion individual units produced worldwide. In Japan alkaline batteries account for 46% of all primary battery sales.

8. Chemistry
In an alkaline battery, the negative electrode is zinc and the positive electrode manganese (IV) oxide. The alkaline electrolyte of potassium hydroxide is not part of the reaction, only the zinc and manganese (IV) oxide are consumed during discharge. The alkaline electrolyte of potassium hydroxide remains, as there are equal amounts of OH− consumed and produced.

9. Section through an alkaline battery
The positive electrode mixture is a compressed paste of manganese (IV) oxide with carbon powder added for increased conductivity.
The negative electrode is composed of a dispersion of zinc powder in a gel containing the potassium hydroxide electrolyte.

10. Secondary cells Lead–acid battery Specific energy 33–42 Wh/kg
Energy density
60–110 Wh/l
Specific power
180 W/kg
Charge/discharge efficiency
50–95%
Energy/consumer- price
7(sld)–18(fld) Wh/US$
Self-discharge rate
3–20%/month
Cycle durability
500–800 cycles
Nominal cell voltage
2.0 V
Charge temperature interval
min. −35 °C, max. 45 °C

11. Lead–acid battery
The lead–acid battery is the oldest type of rechargeable battery. Despite having a very low energy-to-weight ratio and a low energy-to-volume ratio, its ability to supply high surge currents means that the cells have a relatively large power-to-weight ratio. These features, along with their low cost, makes it attractive for use in motor vehicles to provide the high current required by automobile starter motors.

12. Lead–acid battery Discharge Negative plate reaction:
Fully discharged: two identical lead sulfate plates
Discharge
Negative plate reaction:
Positive plate reaction:
The total reaction

13. Li ion battery
An example of a Li-ion battery (used on the Nokia 3310 mobile phone)
Specific energy
100–265 W·h/kg
(0.36–0.95 MJ/kg)
Energy density
250–676 W·h/L
(0.90–2.43 MJ/L)
Specific power
~250-~340 W/kg
Charge/discharge efficiency
80–90%
Energy/consumer-price
2.5 W·h/US$
Self-discharge rate
8% at 21 °C 15% at 40 °C 31% at 60 °C (per month)
Cycle durability
400–1200 cycles
Nominal cell voltage
NMC 3.6 / 3.7 V, LiFePO4 3.2 V

14. Li ion battery
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 constituent components of a lithium-ion battery cell.

15. Li ion battery
Handheld electronics mostly use LIBs based on lithium cobalt oxide (LiCoO2), which offers high energy density, but presents safety risks, especially when damaged.
Lithium iron phosphate (LiFePO4), lithium manganese oxide (LMO) and lithium nickel manganese cobalt oxide (NMC) offer lower energy density, but longer lives and inherent safety. Such batteries are widely used for electric tools, medical equipment and other roles. NMC in particular is a leading contender for automotive applications.
The new lithium sulphur batteries promise the highest performance to weight ratio.

16. Construction
The four primary functional components of a lithium- ion battery are the positive and negative electrodes, separator and electrolyte.

17. Construction

18. Construction
Generally, the negative electrode of a conventional lithium-ion cell is made from carbon. The positive electrode is a metal oxide, and the electrolyte is a lithium salt in an organic solvent. The electrochemical roles of the electrodes reverse between anode and cathode, depending on the direction of current flow through the cell.
The most commercially popular negative electrode is graphite. The positive electrode is generally one of three materials: a layered oxide (such as lithium cobalt oxide), a polyanion聚阴离子 (such as lithium iron phosphate) or a spinel尖晶石 (such as lithium manganese oxide).

19. Construction
The electrolyte is typically a mixture of organic carbonates such as ethylene carbonate or diethyl carbonate containing complexes of lithium ions. These non- aqueous electrolytes generally use non- coordinating非配位 anion阴离子 salts such as lithium hexafluorophosphate (LiPF6)六氟磷酸 锂.

20. Electrochemistry The cathode (marked +) half-reaction is:
The anode (marked -) half reaction is:
Overdischarge supersaturates lithium cobalt oxide, leading to the production of lithium oxide, possibly by the following irreversible reaction:
Overcharge up to 5.2 volts leads to the synthesis of cobalt(IV) oxide, as evidenced by x-ray diffraction:

21. Extreme temperatures
Charging temperature limits for Li-ion are stricter than the operating limits. Lithium-ion chemistry performs well at elevated temperatures but prolonged exposure to heat reduces battery life.
Li‑ion batteries offer good charging performance at cooler temperatures and may even allow 'fast- charging' within a temperature range of 5 to 45 °C. Charging should be performed within this temperature range.

22. Extreme temperatures
At temperatures from 0 to 5 °C charging is possible, but the charge current should be reduced. During a low-temperature charge the slight temperature rise above ambient due to the internal cell resistance is beneficial.
High temperatures during charging may lead to battery degradation and charging at temperatures above 45 °C will degrade battery performance, whereas at lower temperatures the internal resistance of the battery may increase, resulting in slower charging and thus longer charging times.

23. Battery life
Rechargeable battery life is typically defined as the number of full charge-discharge cycles before significant capacity loss. Storage also reduces capacity.
Manufacturers‘ information typically specify lifespan in terms of the number of cycles (e.g., capacity dropping linearly to 80% over 500 cycles), with no mention of chronological age实际年龄. Research rejects this common industry practice. On average, lifetimes consist of 1000 cycles, although battery performance is rarely specified for more than 500 cycles. This means that batteries of mobile phones, or other hand-held devices in daily use, are not expected to last longer than three years.

24. Safety
If overheated or overcharged, Li-ion batteries may suffer thermal runaway and cell rupture. In extreme cases this can lead to combustion.
To reduce these risks, lithium-ion battery packs contain fail-safe circuitry that disconnects the battery when its voltage is outside the safe range of 3–4.2 V per cell. Lithium-ion cells are very susceptible to damage outside the allowed voltage range that is typically within (2.5 to 3.65) V for most LFP cells. Exceeding this voltage range results in premature aging过早老化 of the cells and, furthermore, results in safety risks due to the reactive components in the cells. When stored for long periods the small current draw电流消耗 of the protection circuitry may drain the battery below its shutoff voltage; normal chargers充电器 may then be useless. Many types of lithium-ion cells cannot be charged safely below 0 °C.

25. Capacitors

26. Capacitors
A capacitor is a passive two-terminal electrical component used to store electrical energy temporarily in an electric field.

27. Capacitors
The forms of practical capacitors vary widely, but all contain at least two electrical conductors (plates) separated by a dielectric (i.e. an insulator that can store energy by becoming polarized). The conductors can be thin films, foils or sintered beads of metal or conductive electrolyte, etc. The nonconducting dielectric acts to increase the capacitor‘s charge capacity. A dielectric can be glass, ceramic, plastic film, air, vacuum, paper, mica云母, oxide layer etc.
Capacitors are widely used as parts of electrical circuits in many common electrical devices. Unlike a resistor, an ideal capacitor does not dissipate消散 energy. Instead, a capacitor stores energy in the form of an electrostatic field between its plates.

28. Supercapacitors
Supercapacitors (SC) don’t have a conventional solid dielectric. The capacitance value of an electrochemical capacitor is determined by two storage principles, both of which contribute to the total capacitance of the capacitor: double layer capacitance and pseudo capacitance.

29. Double-layer capacitance
Double-layer capacitance – Storage is achieved by separation of charge in a Helmholtz double layer at the interface between the surface of a conductor and an electrolytic solution电解液溶液. The distance of separation of charge in a double-layer is on the order of a few Angstroms (0.3–0.8 nm). This storage is electrostatic in origin.

30. double layer capacitor
Schematic of double layer capacitor.
1. Inner Helmholtz Layer
2. Outer Helmholtz Layer
3. Diffuse layer
4. Solvated ions 溶剂化离子
5. Specifically adsorptive ions (Pseudocapacitance)
6. Solvent molecule

31. Pseudocapacitance
Pseudocapacitance – Storage is achieved by redox reactions, electrosorbtion or intercalation on the surface of the electrode or by specifically adsorpted ions that results in a reversible faradaic charge- transfer. The pseudocapacitance is faradaic 感应电流的 in origin.
The ratio of the storage resulting from each principle can vary greatly, depending on electrode design and electrolyte composition. Pseudocapacitance can increase the capacitance value by as much as an order of magnitude over that of the double-layer by itself.

32. Supercapacitors
Supercapacitors are divided into three families, based on the design of the electrodes:
Double-layer capacitors – with carbon electrodes or derivates with much higher static double-layer capacitance than the faradaic pseudocapacitance赝电容
Pseudocapacitors准电容器 – with electrodes out of metal oxides or conducting polymers with a high amount of faradaic pseudocapacitance
Hybrid capacitors – capacitors with special and asymmetric electrodes that exhibit both significant double-layer capacitance and pseudocapacitance, such as lithium-ion capacitors

34. Supercapacitors
While existing supercapacitors have energy densities that are approximately 10% of a conventional battery, their power density is generally 10 to 100 times greater.
Power density is defined as the product of energy density, multiplied by the speed at which the energy is delivered to the load. The greater power density results in much shorter charge/discharge cycles than a battery is capable, and a greater tolerance for numerous charge/discharge cycles. This makes them well-suited for parallel connection with batteries, and may improve battery performance in terms of power density.

35. Ragone chart showing power density vs
Ragone chart showing power density vs. energy density of various capacitors and batteries

36. Lithium-ion capacitor
A lithium-ion capacitor is a hybrid electrochemical energy storage device which combines the intercalation mechanism of a lithium ion battery with the cathode of an electric double- layer capacitor (EDLC).
The packaged energy density of an LIC is approximately 20 Wh/kg generally four times higher than an EDLC and five times lower than a lithium ion battery. The power density however has been shown to match that of EDLCs able to completely discharge in seconds.
The negative electrode (cathode) often employs activated carbon material at which charges are stored in an electric double layer that is developed at the interface between the carbon and the electrolyte.

37. Lithium-ion capacitor
The positive electrode (anode) was originally made with lithium titanate oxide, but is now more commonly made with graphitic carbon material to maximize energy density. The graphitic electrode potential initially at -0.1 Volts versus SHE (standard hydrogen electrode) is lowered further to -2.8V by the intercalation of lithium ions. This process step is referred to as doping and often takes place in the device between the anode and a sacrificial lithium electrode. The pre-doping process is critical to the device functioning as it can significantly affect the development of the Solid Electrolyte Interphase layer. Doping the anode lowers the anode potential and leads to a higher output voltage of the capacitor.