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CN-116936968-B - Electrochemical device, charge-discharge method, and electronic apparatus

CN116936968BCN 116936968 BCN116936968 BCN 116936968BCN-116936968-B

Abstract

An electrochemical device, a charge-discharge method and an electronic apparatus, wherein a negative electrode active material of the electrochemical device includes a first active material and a second active material, a theoretical gram capacity of the first active material is smaller than a theoretical gram capacity of the second active material, and an upper limit of a discharge operation voltage of the first active material is higher than an upper limit of a discharge operation voltage of the second active material. The electrochemical device has charge capacities of Q 11 and Q 21 , respectively, of discharge cutoff voltages V 11 and V 21 or discharge cutoff currents I 11 and I 21 , respectively, of a single charge-discharge process of Q 12 and Q 22 , respectively, of a first and second ambient temperatures T 1 and T 2 , respectively, discharge cutoff voltages V 12 and V 22 , respectively, or discharge cutoff currents I 12 and I 22 ;Q 21 and Q 11 , respectively, of not more than 20% in a first cycle interval, and at least one of conditions a) to c) satisfies Q 12 ≤Q 11 ;V 12 ＞V 11 ;I 12 ＞I 11 , and at least one of conditions d) to f) satisfies Q 22 ≤Q 21 ;V 22 ＞V 21 ;I 22 ＞I 21 .

Inventors

  • LIU WEI

Assignees

  • 宁德新能源科技有限公司

Dates

Publication Date
20260512
Application Date
20220331

Claims (10)

  1. 1. An electrochemical device, wherein a negative active material of the electrochemical device includes a first active material and a second active material, a theoretical gram capacity of the first active material is smaller than a theoretical gram capacity of the second active material, an upper limit of a discharge operation voltage of the first active material is higher than an upper limit of a discharge operation voltage of the second active material, At a first ambient temperature T 1 , The electrochemical device has a charge capacity Q 11 and a discharge cut-off voltage V 11 in a single charge-discharge process in a first cycle interval; The electrochemical device has a charge capacity Q 12 during a single charge-discharge process in a second cycle interval, a discharge cut-off voltage V 12 , and satisfies at least one of conditions a) to b): a)Q 12 ≤Q 11 ; b)V 12 ＞V 11 ; At a second ambient temperature, T 2 , T 2 ＞T 1 , The charging capacity of the electrochemical device in a single charging and discharging process of the first cycle interval is that the difference between Q 21 , Q 21 and Q 11 is not more than 20%; the electrochemical device has a discharge cut-off voltage V 21 in a first cycle interval; The electrochemical device has a charge capacity Q 22 during a single charge-discharge process of the second cycle interval, a discharge cut-off voltage V 22 , and satisfies at least one of conditions d) to e): d)Q 22 ≤Q 21 ; e)V 22 ＞V 21 。
  2. 2. The electrochemical device of claim 1, wherein said second active material has a temperature coefficient of less than 0.98.
  3. 3. The electrochemical device of claim 1, wherein a single charge-discharge process of the electrochemical device comprises: Constant-current charging the electrochemical device to a first voltage, and constant-voltage charging the electrochemical device to a first current at the first voltage; constant-current charging the electrochemical device to a second voltage with the first current and constant-voltage charging the electrochemical device to a second current with the second voltage, and And charging the electrochemical device to a third voltage with the second current in a constant current manner, and charging the electrochemical device to a target charging cut-off current with the third voltage in a constant voltage manner.
  4. 4. The electrochemical device of claim 1, wherein T 1 <35℃,35℃≤T 2 +.60 ℃.
  5. 5. The electrochemical device of claim 1 wherein Q 22 differs from Q 12 by no more than 20%.
  6. 6. The electrochemical device of claim 1, wherein the electrochemical device is coupled to a processor configured to: acquiring a current temperature of the electrochemical device; Determining a target charge cutoff current of the electrochemical device according to the current temperature and a first mapping relation between the pre-established temperature and the charge cutoff current, wherein the first mapping relation comprises N temperatures and N corresponding charge cutoff currents, the higher temperature corresponds to the larger charge cutoff current, and N is an integer greater than or equal to 2; And controlling the electrochemical device to charge to the target charge cut-off current.
  7. 7. The electrochemical device of claim 6, wherein the processor is specifically configured to: And determining the temperature closest to the current temperature in the first mapping relation as a target temperature, and determining the charging cut-off current corresponding to the target temperature as the target charging cut-off current.
  8. 8. The electrochemical device of claim 6, wherein the processor is further configured to: acquiring the current charge-discharge cycle number of the electrochemical device; Determining a target cycle interval of the electrochemical device according to the current charge-discharge cycle number; determining a target discharge cutoff voltage according to the target circulation interval and a second mapping relation between a preset circulation interval and the discharge cutoff voltage, wherein the second mapping relation comprises M circulation intervals and corresponding M discharge cutoff voltages in sequence, and the circulation interval with a larger charge-discharge circulation number corresponds to a larger discharge cutoff voltage, wherein M is an integer greater than or equal to 2; Controlling discharge of the electrochemical device until the target discharge cutoff voltage.
  9. 9. An electronic device, characterized in that it comprises the electrochemical apparatus according to claims 1-8.
  10. 10. A charge-discharge method of an electrochemical device, wherein a negative active material of the electrochemical device includes a first active material and a second active material, a theoretical gram capacity of the first active material is smaller than a theoretical gram capacity of the second active material, and an upper limit of a discharge operation voltage of the first active material is higher than an upper limit of a discharge operation voltage of the second active material, the method comprising: At a first ambient temperature T 1 , Controlling the charge capacity of the electrochemical device in a single charge-discharge process of a first cycle interval to be Q 11 , and having a discharge cut-off voltage V 11 ; Controlling the electrochemical device to have a charge capacity Q 12 , a discharge cut-off voltage V 12 , and at least one of conditions a) to b): a)Q 12 ≤Q 11 ; b)V 12 ＞V 11 ; At a second ambient temperature, T 2 , T 2 ＞T 1 , The charging capacity of the electrochemical device in a single charging and discharging process of the first cycle interval is controlled to be Q 21 , so that the degree of difference between Q 21 and Q 11 is not more than 20%; the electrochemical device has a discharge cut-off voltage V 21 in a first cycle interval; Controlling the charge capacity of the electrochemical device in a single charge-discharge process of the second cycle interval to be Q 22 with a discharge cut-off voltage V 22 , wherein at least one of conditions d) to e) is satisfied: d)Q 22 ≤Q 21 ; e)V 22 ＞V 21 。

Description

Electrochemical device, charge-discharge method, and electronic apparatus Technical Field The embodiment of the application relates to the technical field of batteries, in particular to an electrochemical device, a charging and discharging method and electronic equipment. Background The cycle performance of an electrochemical device directly affects its life and quality. The better the cycle performance, the longer the life of the electrochemical device, which can reduce not only the use cost of the user but also the resource consumption. The cycle performance of the electrochemical device includes normal temperature cycle performance and high temperature cycle performance. For silicon-based batteries and other electrochemical devices with low temperature coefficients, the high temperature cycle performance is very different from the normal temperature cycle performance. Taking a silicon system battery as an example, due to the characteristics of the silicon system battery, the voltage platform is lower, the temperature coefficient is lower, the charging capacity at high temperature is higher than that at normal temperature, the positive electrode of the silicon system battery is over-delithiated, and the high-temperature cycle performance of the silicon system battery is seriously deteriorated. In addition, during long-term use of the silicon system battery, the silicon material expands, which affects the cycle performance of the full life cycle of the silicon system battery. Disclosure of Invention In view of the above, embodiments of the present application provide an electrochemical device, a charge-discharge method and an electronic apparatus, so as to at least partially solve the above-mentioned problems. According to a first aspect of an embodiment of the present application, there is provided an electrochemical device, a negative active material of which includes a first active material and a second active material, a theoretical gram capacity of the first active material being smaller than a theoretical gram capacity of the second active material, an upper limit of a discharge operation voltage of the first active material being higher than an upper limit of a discharge operation voltage of the second active material, At a first ambient temperature T 1, the electrochemical device has a charge capacity of Q 11 during a single charge-discharge process of a first cycle interval, and has a discharge cutoff voltage V 11 or a discharge cutoff current I 11; The electrochemical device has a charge capacity Q 12 during a single charge-discharge process in a second cycle interval, and has a discharge cut-off voltage V 12 or a discharge cut-off current I 12, wherein at least one of conditions a) to c) is satisfied: a)Q12≤Q11; b)V12＞V11; c)I12＞I11; At a second ambient temperature T 2 and T 2＞T1, the electrochemical device has a charging capacity of Q 21 in a single charging and discharging process in the first cycle interval, and the difference between Q 21 and Q 11 is not more than 20%, and the electrochemical device has a discharging cut-off voltage V 21 or a discharging cut-off current I 21 in the first cycle interval; The electrochemical device has a charge capacity Q 22 during a single charge-discharge process in the second cycle interval, and has a discharge cut-off voltage V 22 or a discharge cut-off current I 22, wherein at least one of conditions d) to f) is satisfied: d)Q22≤Q21; e)V22＞V21; f)I22＞I21。 in a possible implementation manner, in combination with the first aspect, a temperature coefficient of the second active material is lower than 0.98. In another possible implementation manner, in combination with the first aspect, the second active material includes a transition metal oxide. In a further possible implementation manner, with reference to the first aspect, the single charge-discharge process of the electrochemical device includes constant-current charging the electrochemical device to a first voltage at a charging current and constant-voltage charging the electrochemical device to a first current at the first voltage, constant-current charging the electrochemical device to a second voltage at the first current and constant-voltage charging the electrochemical device to a second current at the second voltage, and constant-current charging the electrochemical device to a third voltage at the second current and constant-voltage charging the electrochemical device to a target charge-off current at the third voltage. In a further possible implementation manner, in combination with the above first aspect, T 1<35℃,35℃≤T2 is less than or equal to 60 ℃. In a further possible implementation manner, in combination with the first aspect, a degree of difference between Q 22 and Q 12 is not greater than 20%. In a further possible implementation manner, with reference to the first aspect, the electrochemical device is connected to a processor, and the processor is configured to obtain a current temperat