Battery system, vehicle with such a battery system, and method for operation of such a battery system

The invention relates to a battery system with a battery module (2) comprising a plurality of battery cells (3), wherein the battery cells (3) take the form, in particular, of lithium-ion battery cells or lithium-polymer battery cells, wherein the battery system (1) exhibits a first temperature-control-fluid guide (4) which is designed to be capable of being flowed through by a first temperature-control fluid (5) and, moreover, exhibits a first conveying unit (6) designed for a conveyance of the first temperature-control fluid (5) through the first temperature-control-fluid guide (4), and wherein the first temperature-control-fluid guide (4) is connected to the battery module (2) in heat-conducting manner, wherein the battery system (1) exhibits a second temperature-control-fluid guide (7) which is designed to be capable of being flowed through by a second temperature-control fluid (8) and, moreover, exhibits a second conveying unit (9) designed for an uptake of kinetic energy from the second temperature-control fluid (8), wherein the second temperature-control-fluid guide (7) exhibits at least one port (10) designed for a fluid-conducting connection to a further temperature-control-fluid guide (11), wherein the battery system (1) exhibits, moreover, a heat-exchanger unit (12) designed to the first temperature-control-fluid guide (4) and to the second temperature-control-fluid guide (7) in heat-conducting manner, which is designed to transfer heat between the first temperature-control-fluid guide (4) and the second temperature-control-fluid guide (7), wherein the first conveying element (6) and the second conveying element (9) are connected to one another in coupled manner in such a way that mechanical work can be transferred from the second conveying element (9) to the first conveying element (6).