Editing Lithium polymer battery (section)

== Future developments ==

A solid polymer electrolyte (SPE) is a solvent-free salt solution in a polymer medium. It may be, for example, a compound of lithium bis(fluorosulfonyl)imide (LiFSI) and high molecular weight [[Polyethylene glycol|poly(ethylene oxide)]] (PEO),<ref name="polymer 1">{{cite journal |journal=Electrochimica Acta |volume=133 |date=1 July 2014 |pages=529–538 |title=Lithium bis(fluorosulfonyl)imide/poly(ethylene oxide) polymer electrolyte |last1=Zhang |first1=Heng |last2=Liu |first2=Chengyong |last3=Zheng |first3=Liping |doi=10.1016/j.electacta.2014.04.099}}</ref> a high molecular weight [[poly(trimethylene carbonate)]] (PTMC),<ref name="polymer 2">{{cite journal |journal=Solid State Ionics |volume=262 |date=1 September 2014 |pages=738–742 |title=Polycarbonate-based solid polymer electrolytes for Li-ion batteries |last1=Sun |first1=Bing |last2=Mindemark |first2=Jonas |last3=Edström |first3=Kristina |author-link3=Kristina Edström |last4=Brandell |first4=Daniel |doi=10.1016/j.ssi.2013.08.014}}</ref> polypropylene oxide (PPO), poly[bis(methoxy-ethoxy-ethoxy)phosphazene] (MEEP), ''etc''. PEO exhibits the most promising performance as a solid solvent for lithium salts, mainly due to its flexible ethylene oxide segments and other oxygen atoms that comprise a strong donor character, readily solvating Li<sup>+</sup> cations. PEO is also commercially available at a very reasonable cost.<ref name=":0" /> The performance of these proposed electrolytes is usually measured in a [[half-cell]] configuration against an electrode of metallic [[lithium]], making the system a "[[lithium battery|lithium-metal]]" cell. Still, it has also been tested with a common lithium-ion cathode material such as [[Lithium iron phosphate battery|lithium-iron-phosphate]] (LiFePO<sub>4</sub>).

Cells with solid polymer electrolytes have not been fully commercialised<ref>{{cite web |last1=Blain |first1=Loz |title=Solid state battery breakthrough could double the density of lithium-ion cells |url=https://newatlas.com/science/deakin-solid-state-battery-polymer-electrolyte/ |website=New Atlas |date=27 November 2019 |publisher=Gizmag |access-date=6 December 2019}}</ref> and are still a topic of research.<ref>{{cite journal |last1=Wang |first1=Xiaoen |last2=Chen |first2=Fangfang |last3=Girard |first3=Gaetan M.A. |last4=Zhu |first4=Haijin |last5=MacFarlane |first5=Douglas R. |last6=Mecerreyes |first6=David |last7=Armand |first7=Michel |last8=Howlett |first8=Patrick C. |last9=Forsyth |first9=Maria |title=Poly(Ionic Liquid)s-in-Salt Electrolytes with Co-coordination-Assisted Lithium-Ion Transport for Safe Batteries |journal=Joule |date=November 2019 |volume=3 |issue=11 |pages=2687–2702 |doi=10.1016/j.joule.2019.07.008 |doi-access=free }}</ref> Prototype cells of this type could be considered to be between a traditional [[lithium-ion]] battery (with liquid electrolyte) and a completely plastic, [[solid-state lithium-ion battery]].<ref name="book_3"/> The simplest approach is to use a polymer matrix, such as [[polyvinylidene fluoride]] (PVdF) or [[polyacrylonitrile|poly(acrylonitrile)]] (PAN), gelled with conventional salts and solvents, such as [[lithium hexafluorophosphate|LiPF<sub>6</sub>]] in [[Ethylene carbonate|EC]]/[[Dimethyl carbonate|DMC]]/[[Diethyl carbonate|DEC]].

Other attempts to design a polymer electrolyte cell include the use of [[inorganic chemistry|inorganic]] [[ionic liquid]]s such as 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIM]BF<sub>4</sub>) as a plasticizer in a microporous polymer matrix like poly(vinylidene fluoride-co-hexafluoropropylene)/poly(methyl methacrylate) (PVDF-HFP/PMMA).<ref name="polymer 3">{{cite journal |journal=Electrochimica Acta |volume=133 |date=1 July 2014 |pages=623–630 |title=Study of PVDF-HFP/PMMA blended micro-porous gel polymer electrolyte incorporating ionic liquid [BMIM]BF<sub>4</sub> for Lithium ion batteries |last1=Zhai |first1=Wei |last2=Zhu |first2=Hua-jun |last3=Wang |first3=Long |doi=10.1016/j.electacta.2014.04.076}}</ref>