NOVELTY - A mixture (Ia) contains a mixture (IIa) and borate, carbonate, phosphate, sulfate and/or silicate ester(s). Mixture (IIa) consists of a solid with a primary particle size of 5 nm to 20 mum and a polymer.    USE - The mixture or composite (A) is used for the production of and in a solid state electrolytes, separator or electrode, sensor, electrochemical window, display, capacitor or ion-conducting film (claimed). The electrochemical cell (EC) is used as car battery, battery in equipment or flat battery (all claimed) or polymer battery.    ADVANTAGE - The solid (III) increases the resistance to short circuits and the compression strength, especially at temperatures above 120degreesC, and also increases the porosity, which suppressed the formation of lithium dendrites. The solid also improves the cycle stability and increases the current capacity of electrochemical cells. If the solid is basic, is neutralizes acid formed during operation of am electrochemical cell. Addition of the esters (E1-5) improves the mechanical properties of foils made from the mixture and facilitates peel from temporary substrates. The esters also act as electrolytes.    DETAILED DESCRIPTION - Mixture (Ia) contains a mixture (IIa) and borate, carbonate, phosphate, sulfate and/or silicate ester(s) of formulae (E1-5). Mixture (IIa) consists of    (a) 1-95 wt.% solid (III), preferably a basic solid, with a primary particle size of 5 nm to 20 mum and    (b) 5-99 wt.% polymer (IV) where (IV) is obtained by polymerization of    (i) 5-100 wt.% condensation product (V) of compound(s) (VI) reacting with carboxylic and/or sulfonic acid(s) and/or derivative(s) and not less than 1 mole/mole (VI) of a carboxylic or sulfonic acid (VII) containing functional group(s) subject to free radical polymerization; and    (ii) 0-95 wt.% compound (VIII) with a number average molecular weight (Mn) not less than 5000, which has polyether segments in the main or side chain.    R1, R2, R3, R4 = linear or branched 1-4 carbon (C) alkyl, (-CH2-CH2-O)n-CH3, 3-6 C cycloalkyl or optionally substituted aromatic hydrocarbyl;    n = 1-3;    at least one of R1, R2, R3, R4 = (-CH2-CH2-O)n-CH3    INDEPENDENT CLAIMS are included for:-    (1) Another mixture (Ib) containing a different polymer (IX) which also has polyether segments in the main or side chain.    (2) A composite (A) comprising a first layer containing an electron-conductive, electrochemically active compound and a second layer of mixture free from a compound of this type;    (3) Solid state electrolytes (B), separators (C), electrodes (D), sensors, electrochromic windows, displays, capacitors and ion conducting films containing the composite (A); and    (4) An electrochemical cell (EC) containing (B), (C) and/or (D).