TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Composition: The borate-based anion is chosen from bis(oxalato)borate, difluorooxalatoborate, bis(malonato)borate, bis(perfluoropinacolato)borate, tetrafluoroborate, triborate, tetraborate and metaborate. The ionic liquid comprises cation chosen from lithium cation, optionally substituted imidazolium cation, optionally substituted piperidinium cation, optionally substituted pyrrolidinium cation, optionally substituted pyrazolium cation, optionally substituted triazolium cation, optionally substituted isotriazolium cation, optionally substituted thiazolium cation, optionally substituted oxazolium cation, optionally substituted isooxazolium cation, optionally substituted pyridazinium cation, optionally substituted pyrimidinium cation, optionally substituted pyrazinium cation, optionally substituted pyridinium cation, optionally substituted isothiazolium cation, optionally substituted azathiazolium cation, optionally substituted oxothiazolium cation, optionally substituted oxaborolium cation, optionally substituted dithiazolium cation, optionally substituted selenozolium cation, optionally substituted oxaphospholium cation, optionally substituted pyrrollium cation, optionally substituted borolium cation, optionally substituted furanium cation, optionally substituted thiophenium cation, optionally substituted pentazolium cation, optionally substituted indolium cation, optionally substituted indolinium cation, optionally substituted tetrazolium cation, optionally substituted benzofuranium cation, optionally substituted dibenzofuranium cation, optionally substituted benzothiophenium cation, optionally substituted dibenzothiophenium cation, optionally substituted thiadiazolium cation, optionally substituted piperazinium cation, optionally substituted morpholinium cation, optionally substituted pyranium cation, optionally substituted annolinium cation, optionally substituted phthalazinium cation, optionally substituted quinazolinium cation, optionally substituted quinazalinium cation, optionally substituted quinolinium cation, optionally substituted isoquinolinium cation, optionally substituted thiazinium cation, optionally substituted oxazinium cation, optionally substituted azaannulenium cation, optionally substituted phosphonium cation and optionally substituted ammonium cation.    TECHNOLOGY FOCUS - POLYMERS - Preferred Composition: The polymer compound is ester-containing polymer compound and fluorine-based polymer compound. The ester-containing polymer compound chosen from optionally substituted carboxylate-containing polymer compound and optionally substituted (meth)acrylate-containing polymer compound. The positive electrode protective layer composition contains (in weight%) polymer compound (1-20 weight%), ionic liquid (1-10 weight%) and solvent (70-98 weight%).