What is the battery of the heat battery?LiFePO4 battery

A thermal battery is a primary storage battery that is activated by melting a molten salt as an electrolyte and melting it with a heat source. Because of its high specific energy and specific power, wide operating environment temperature, long storage time, fast and reliable activation, compact structure, simple process, low cost, and no maintenance, it has been favored by the military for development. It is an ideal power source for modern weapons such as missiles, nuclear weapons and artillery, and it plays an important role in the military field.

The early thermal battery mainly used cup-type structure, the cathode material used WO3/V2O5, etc., the anode material used Ca, Mg, etc., the electrolyte material was LiCl-KCl eutectic sucked on the glass cloth, and the heating material was Zr-BaCrO4 Pilot paper. The battery has a complicated structure, a short discharge time, and severe electrical noise, which greatly limits its use. The Ca/CaCrO4 thermal battery developed in the 1960s uses an advanced sheet structure with LiCl-KCl as the electrolyte and a Fe/KClO4 mixture as the heating material. The battery not only greatly simplifies the preparation process, but also prolongs the working life and improves the overall performance of the thermal battery, but the electrical noise existing in the thermal battery has not been overcome. In order to meet the needs of high-speed development of modern weapons, the LiMx/FeS2 thermal battery (LiMx is a lithium alloy) developed in the 1970s not only overcomes the long-term electrical noise of the thermal battery, but also greatly improves the specific energy and specific power. It is an ideal thermal battery system and a major technological breakthrough in the development of thermal batteries, representing the current trend of thermal battery development.

On the basis of learning foreign advanced technology, the development of China's thermal battery has completed the journey of the initial stage of development of foreign thermal batteries in a short period of time. In the 1970s, it began to develop LiMx/FeS2 with advanced countries. Thermal battery system. In the 1980s, major technological advances were made, and various products were developed and successfully applied to weapons. LiMx/FeS2 thermal batteries are currently the preferred product in the newly developed weapon system. A multi-component, competitive and competitive thermal battery development and production system has been formed.

A thermal battery is a thermally activated primary reserve battery. Generally, a stack consisting of a plurality of single cell strings, connected in parallel with a heating sheet, is placed in a combined casing, and the stack is connected to a terminal on the battery cover through a drain bar, and the entire battery is composed of a stack, an activation mechanism, and a combination. The shell, the composite cover and the like are formed by argon arc welding.

The single cell is composed of a positive electrode, an electrolyte, and a negative electrode, and each of the single cells is provided with a heating sheet at both ends. When the battery is required to work, use an external electrical signal or mechanical force to ignite the igniter inside the battery, and ignite the heating system inside the battery to make the single battery reach its working temperature (400-600 ° C), which will be non-conductive at normal temperature. The solid electrolyte is heated and melted into an ionic conductor, and an electrochemical reaction occurs between the positive and negative electrodes to generate electrical energy. After being connected to the external line, the battery enters a working state.

The working life of a thermal battery is controlled by both the electrical and thermal life of the battery. The electrical life refers to the reaction characteristics of the battery, that is, the working time that the battery should be discharged within a specified voltage range and discharged under a specified load. Thermal life refers to the temperature characteristic of the battery, that is, the time during which the battery is maintained within a suitable operating temperature range. When the active material of the battery is exhausted, the electrical life is terminated, the working life of the battery is terminated, and when the internal temperature of the battery drops to the freezing point of the electrolyte, At the end of the thermal life, the battery's working life is also terminated.

The operation of the thermal battery is divided into two processes, one is the activation process of the battery, and the other is the discharge process of the battery. The battery is activated, the internal working temperature of the battery rises rapidly from normal temperature to its highest temperature (about 550 °C), which is the activation process of the battery; then the battery enters the discharge process, during the discharge of the battery, the internal temperature of the battery is discharged Slow down. The activation process of the thermal battery is the activation process of the battery, during which the internal resistance of the thermal battery is quickly increased by several hundred M! Change to a few ", even a few hundred. After the battery enters the working state, as the discharge progresses, the temperature inside the battery slowly decreases, the ionic conductivity of the electrolyte is weakened, and the internal resistance of the battery is correspondingly increased, when the temperature drops. To a certain extent, the electrolyte gradually solidifies.