CN117199576A - Charging method of lithium battery with silicon-containing negative electrode - Google Patents
Charging method of lithium battery with silicon-containing negative electrode Download PDFInfo
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- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 title claims abstract description 325
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 title claims abstract description 208
- 229910052710 silicon Inorganic materials 0.000 title claims abstract description 208
- 239000010703 silicon Substances 0.000 title claims abstract description 208
- 238000000034 method Methods 0.000 title claims abstract description 67
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims abstract description 101
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- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 2
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Abstract
The invention provides a charging method of a lithium battery with a silicon-containing negative electrode, which is characterized by comprising the following steps of: comprises a first charging stage and a second charging stage; in the first charging stage, charging with a C1 rate; in the second charging stage, charging with a C2 rate; wherein, C1 and C2 satisfy the following relation: c1 =n1×n2×c2× (p1×w1)/(p1×w1+p2×w2); wherein n1=0.3 to 0.7, n2=3.6 to 5×w1; c2 =1.25 to 12; wherein, in the silicon-containing anode, the anode active material includes silicon and graphite, P1 represents a silicon reversible capacity, P2 represents a graphite reversible capacity, W1 represents a silicon content, and W2 represents a graphite content; in the charging process of the lithium battery, when the SOC value of the lithium battery reaches a threshold value a in a first charging stage, the first charging stage is ended, and the charging stage is switched to a second charging stage; where a=n1× (p1×w1)/(p1×w1+p2×w2). The charging method is beneficial to improving the stability of the silicon particles in the charging process, ensuring the long-term exertion of the capacity of the silicon particles, optimizing the cycle performance of the battery and reducing the charging time.
Description
Technical Field
The invention belongs to the technical field of lithium batteries, and particularly relates to a charging method of a lithium battery with a silicon-containing negative electrode.
Background
Lithium precipitation is a major cause of affecting the rapid charging of lithium ion batteries, and is the direct reduction of lithium ions to metallic lithium at the surface of the negative electrode rather than into the negative electrode. During rapid charging of lithium ion batteries, there is a large polarization inside the battery, including ohmic impedance, concentration overpotential, and charge transfer overpotential, which can result in a large voltage loss.
Among the currently found lithium ion battery anode materials, the theoretical mass specific capacity of the silicon-based material is highest and is 4200 mAh.g -1 In addition, the embedding potential of the silicon-based material to the matrix is slightly higher than that of the graphite-based material, dendrites are not easy to form on the surface of the material, so that the safety problem is caused, and the silicon-based material becomes a cathode material with great potential and attractive.
In the current silicon-based anode materials, the silicon/graphite anode materials are widely researched and applied because the silicon and graphite raw materials are easy to obtain and have relatively stable electrochemical properties. The silicon is used as a semiconductor material, the ion migration capability of the silicon is poor, the highest multiplying power is calculated according to the requirement of quick charge time in each step according to the existing step charge strategy, and then the steps are sequentially reduced. In this method, since the silicon particles cannot adapt to the rapid lithium removal rate at first, the polarization phenomenon of the battery is aggravated, the input voltage cannot correspond to the charge amount, that is, the input energy is lost ineffectively, the charging time is prolonged finally,
Therefore, the method for charging the lithium battery suitable for the silicon/graphite negative electrode has great practical significance in improving the cycle capacity performance and the charging efficiency of the battery.
Disclosure of Invention
In order to solve the problems and the defects in the prior art, the invention provides a charging method of a lithium battery with a silicon negative electrode, which is beneficial to improving the stability of silicon particles in a charging process, ensuring the long-term exertion of the capacity of the silicon particles, optimizing the cycle performance of the battery and reducing the charging time.
The invention provides a charging method of a lithium battery with a silicon-containing negative electrode, which comprises a first charging stage and a second charging stage; in the first charging stage, charging with a C1 rate; in the second charging stage, charging with a C2 rate; wherein, C1 and C2 satisfy the following relation: c1 =n1×n2×c2× (p1×w1)/(p1×w1+p2×w2); wherein n1=0.3 to 0.7, n2=3.6 to 5×w1; c2 =1.25 to 12; wherein, in the silicon-containing anode, the anode active material includes silicon and graphite, P1 represents a silicon reversible capacity, P2 represents a graphite reversible capacity, W1 represents a silicon content, and W2 represents a graphite content; in the charging process of the lithium battery, when the SOC value of the lithium battery reaches a threshold value a in a first charging stage, the first charging stage is ended, and the charging stage is switched to a second charging stage; where a=n1× (p1×w1)/(p1×w1+p2×w2).
In the above formula, the silicon reversible content (P1) represents the first delithiation gram capacity of a half cell made of a silicon negative electrode sheet (where silicon negative electrode sheet means that the negative electrode active material is silicon only); the half cell is manufactured as follows: 1.5g of Carbon Nano Tube (CNT) and 15g of carboxymethyl cellulose (CMC) glue solution with the solid content of 1.4% are taken for homogenate, then 0.09g of conductive carbon black (SP) is weighed, 2.7g of negative electrode active substance is weighed, 9g of water is added for uniform stirring, and the obtained negative electrode slurry is coated on a negative electrode current collector for 350 mu m and baked for 2 hours at 80 ℃ to obtain a negative electrode plate; the negative plate and the lithium foil form a button cell, and the button cell is placed for at least 12 hours; the test method is as follows: standing for 2h; discharge to 5mv at 0.1C magnification; discharging to 5mv at 0.05C multiplying power; discharging to 5mv at 0.02C multiplying power; discharge to 5mv at 0.01C rate; charging to 2V at 0.1C multiplying power; the silicon reversible capacity was then calculated. Here, the reversible capacity of silicon=silicon (delithiated capacity/anode active material mass; the reversible capacity in the rate formula has been normalized to gram capacity.
The graphite reversible capacity (P2) represents the first delithiation gram capacity of a half battery made of a graphite negative electrode sheet (the graphite negative electrode sheet refers to a negative electrode active material only including graphite); the half cell is manufactured as follows: 1.5g of CNT and 15g of CMC glue solution with the solid content of 1.4 percent are taken for homogenate, 0.09g of gSP is taken, 2.7g of negative electrode active substance is taken, 9g of water is added for stirring, 350um is coated, and 2H is baked at 80 ℃; the negative plate and the lithium foil form a button cell, and the button cell is placed for at least 12 hours; the test method is as follows: standing for 2h; discharge to 5mv at 0.1C magnification; discharging to 5mv at 0.05C multiplying power; discharging to 5mv at 0.02C multiplying power; discharge to 5mv at 0.01C rate; charging to 2V at 0.1C multiplying power; the reversible capacity of the graphite was then calculated. Here, graphite reversible capacity = graphite delithiation capacity/anode active material mass; the reversible capacity in the multiplying power formula has been normalized to gram capacity.
The silicon content (W1) represents the ratio of the mass of silicon to the total mass of silicon and graphite; the graphite content (W2) represents the ratio of the mass of graphite to the total mass of silicon and graphite.
n1 represents the silicon ratio of the pre-intercalated lithium, i.e., the mass of lithium intercalated silicon is a proportion of the mass of all silicon; the value of n1 is a value obtained from long-term experience; specifically, n1 is lower than 0.3, which results in redundant lithium intercalation capability of silicon and excessively long fast charge time; an n1 higher than 0.7 tends to cause an excessively high silicon-to-lithium ratio per unit time of silicon, and a large internal stress is generated inside the silicon particles. n2 represents the charging multiplying power at the maximum current density that silicon can bear, and is a value when the silicon reaches the 3C multiplying power according to the corresponding silicon surface current density in the actual test, wherein the fact that the silicon cannot bear means that the silicon surface current density is too large, and the generated internal stress breaks silicon particles, so that the loss of active lithium is increased. C2 represents the maximum rate required for the preset fast charge time, calculated by using the following formula: c2 =60/preset fast charge time, calculated from the fast charge time of the conventional battery being 5-48 minutes as the preset fast charge time.
In the charging method of the lithium battery with the silicon-containing negative electrode, the lithium battery is charged by adopting the smaller charging multiplying power C1, and then the lithium battery is charged by adopting the larger charging multiplying power C2, so that the stability of silicon particles in the silicon-containing negative electrode in the charging process is improved, the long-term capacity performance of the silicon particles is improved, the capacity attenuation rate of the lithium battery in a quick charging cycle is reduced, and the cycle performance of the lithium battery is improved.
The reason for the above results is that in the silicon/graphite composite anode, when the lithium battery is charged, silicon is lithiated first, i.e., lithium ions are intercalated into silicon particles first, and if the silicon particles are charged at a larger rate, the volume expansion change of the silicon particles is larger, and polarization due to poor lithium ion transmission kinetics of the silicon is larger, so that stability and capacity exertion of the silicon are deteriorated at a large rate, and thus cycle performance of the lithium battery is deteriorated. In the invention, the battery is charged by adopting the lower charging multiplying power, so that the silicon particles can have sufficient time for lithium intercalation in the initial stage, and the silicon particles can not bear excessive internal stress due to the excessive charging multiplying power in the initial stage, thereby being beneficial to slow expansion of the silicon particles, reducing the expansion change volume of the silicon particles and reducing polarization. After the lithium battery is charged for a certain time by using a smaller charging multiplying power, at the moment, certain content of silicon particles are prelithiated to a certain extent, namely lithium ions are embedded in the silicon particles with a certain content, at the moment, the charging multiplying power is switched to a larger charging multiplying power, the residual content of silicon particles and graphite particles are lithiated together during charging, and the lithium ion transmission dynamics performance of graphite is better than that of silicon, so that the larger charging multiplying power is adopted at the moment, too large internal stress can not be generated on the silicon particles, the stability of the silicon particles in the whole charging process is improved, the capacity exertion of the silicon particles is facilitated, the integral stability of the silicon/graphite negative electrode material is improved, and the cycle performance of the lithium battery is optimized.
Although the prior art also uses a small multiplying power and then uses a large multiplying power to charge the lithium battery, most of the charging methods in the prior art are directed to charging most of the batteries, for example, charging different batteries by using the same charging mode, but such charging mode is not suitable for each battery. Because the specific materials used in making the cells will vary from cell to cell, and thus the stress bearing capacity of the active material particles will vary from cell to cell, the corresponding C1 will also vary. If the same charging mode is adopted for different batteries, the charging performance and the cycle performance of the lithium battery are inevitably affected to a certain extent, and the cycle performance of the lithium battery is deteriorated faster by adopting an unsuitable charging mode for a long time. By controlling various factors influencing C1, the invention can determine an optimal C1 value for each different lithium battery, can provide a personalized charging mode for each lithium battery, is beneficial to long-term exertion of the capacity of the lithium battery and is beneficial to the cycle performance of the lithium battery.
In the above relation of the charging magnifications C1 and C2 in the first and second charging phases, the value of C2 is generally related to the fast charging requirement time, and the C2 is related to the fast charging requirement time for the maximum charging magnifications required by the fast charging requirement time, so that on one hand, it is beneficial to setting different maximum charging magnifications according to the requirements of customers, and on the other hand, it is beneficial to improving the charging efficiency of the lithium battery while ensuring the stability of the silicon/graphite anode material. While C1 is related to C2, but also to the charge ratio n2, the reversible capacity P1, the silicon content W1, the reversible capacity P2 of graphite and the graphite content W2 at the maximum current density that can be tolerated by the pre-lithium-intercalated silicon, C1 is more influenced by the reversible capacity of silicon because it determines the kinetics of lithium ion deintercalation of the silicon particles, whereas in the silicon/graphite composite anode, the silicon particles have poor ion transport capacity relative to the graphite particles and are susceptible to volume expansion causing silicon particle breakage leading to increased polarization. Therefore, in the silicon/graphite composite negative electrode, C1 and C2 meet the relation, so that the silicon particles have proper lithium intercalation speed in the initial charging process, the silicon particles have smaller internal pressure under smaller charging multiplying power C1, the silicon particles are not easy to break, the stability of the silicon particles is facilitated, the long-term capacity performance of the silicon particles is further facilitated, and the cycle performance of the lithium battery is improved. And other factors n1, W1, P2 and W2 can influence the lithium intercalation and deintercalation performance of the whole silicon/graphite composite negative electrode to a certain extent, and the cycle performance of the lithium battery is larger. Therefore, the C1 is related to the influence factors, so that the lithium intercalation-deintercalation performance and the stability of the whole silicon/graphite composite negative electrode are fully considered, and the small charging rate C1 more suitable for the lithium battery of the silicon/graphite composite negative electrode in the first charging stage is more beneficial to be obtained.
In addition, regarding the charge magnification n2 at the maximum current density that silicon can withstand, it is related to the silicon content W1, and the higher the silicon content, the smaller n 2. This is because the higher the silicon content, the lower the initial efficiency of the lithium battery, i.e., the lower the maximum current density that can be tolerated per unit mass of silicon. Therefore, the silicon content determines the charge rate at the maximum current density that silicon can withstand, and the silicon content also has a significant impact on the charging performance of the overall lithium battery system.
And switches to the second charging phase as to when the first charging phase ends, which is determined by the SOC value of the battery. When the SOC reaches the threshold b in the first charging stage, it means that a certain content of silicon in the silicon/graphite composite electrode has been intercalated with lithium, the polarization of the lithium battery is relatively low, and the remaining content of silicon and graphite can be intercalated with lithium at the same time, so that graphite particles disperse a part of internal stress, and even under a larger charging rate, the silicon particles are not broken, so that the lithium battery has better stability. The threshold b is related to the silicon ratio n1 of the pre-intercalated lithium, the silicon reversible capacity P1, the silicon content W1, the graphite reversible capacity P2 and the graphite content W2, and the lithium deintercalation performance and the stability of the silicon/graphite composite negative electrode are considered to have a larger correlation with the factors, so that the factors are comprehensively considered, the stress bearing of the silicon/graphite composite negative electrode is favorably judged, the more proper threshold b is obtained, the stability of silicon particles is ensured, and the charging efficiency of the lithium battery is improved to the greatest extent.
Detailed Description
The invention provides a charging method of a lithium battery with a silicon-containing negative electrode, which comprises a first charging stage and a second charging stage; in the first charging stage, charging with a C1 rate; in the second charging stage, charging with a C2 rate; wherein, C1 and C2 satisfy the following relation: c1 =n1×n2×c2× (p1×w1)/(p1×w1+p2×w2); wherein n1=0.3 to 0.7, n2=3.6 to 5×w1; c2 =1.25 to 12; wherein, in the silicon-containing anode, the anode active material includes silicon and graphite, P1 represents a silicon reversible capacity, P2 represents a graphite reversible capacity, W1 represents a silicon content, and W2 represents a graphite content; in the charging process of the lithium battery, when the SOC value of the lithium battery reaches a threshold value a in a first charging stage, the first charging stage is ended, and the charging stage is switched to a second charging stage; where a=n1× (p1×w1)/(p1×w1+p2×w2).
In the charging method of the lithium battery with the silicon-containing negative electrode, the lithium battery is charged by adopting the smaller charging multiplying power C1, and then the lithium battery is charged by adopting the larger charging multiplying power C2, so that the stability of silicon particles in the silicon-containing negative electrode in the charging process is improved, the long-term capacity performance of the silicon particles is improved, the capacity attenuation rate of the lithium battery in a quick charging cycle is reduced, and the cycle performance of the lithium battery is improved.
The reason for the above results is that in the silicon/graphite composite anode, when the lithium battery is charged, silicon is lithiated first, i.e., lithium ions are intercalated into silicon particles first, and if the silicon particles are charged at a larger rate, the volume expansion change of the silicon particles is larger, and polarization due to poor lithium ion transmission kinetics of the silicon is larger, so that stability and capacity exertion of the silicon are deteriorated at a large rate, and thus cycle performance of the lithium battery is deteriorated. In the invention, the battery is charged by adopting the lower charging multiplying power, so that the silicon particles can have sufficient time for lithium intercalation in the initial stage, and the silicon particles can not bear excessive internal stress due to the excessive charging multiplying power in the initial stage, thereby being beneficial to slow expansion of the silicon particles, reducing the expansion change volume of the silicon particles and reducing polarization. After the lithium battery is charged for a certain time by using a smaller charging multiplying power, at the moment, certain content of silicon particles are prelithiated to a certain extent, namely lithium ions are embedded in the silicon particles with a certain content, at the moment, the charging multiplying power is switched to a larger charging multiplying power, the residual content of silicon particles and graphite particles are lithiated together during charging, and the lithium ion transmission dynamics performance of graphite is better than that of silicon, so that the larger charging multiplying power is adopted at the moment, too large internal stress can not be generated on the silicon particles, the stability of the silicon particles in the whole charging process is improved, the capacity exertion of the silicon particles is facilitated, the integral stability of the silicon/graphite negative electrode material is improved, and the cycle performance of the lithium battery is optimized.
Although the prior art also uses a small multiplying power and then uses a large multiplying power to charge the lithium battery, most of the charging methods in the prior art are directed to charging most of the batteries, for example, charging different batteries by using the same charging mode, but such charging mode is not suitable for each battery. Because the specific materials used in making the cells will vary from cell to cell, and thus the stress bearing capacity of the active material particles will vary from cell to cell, the corresponding C1 will also vary. If the same charging mode is adopted for different batteries, the charging performance and the cycle performance of the lithium battery are inevitably affected to a certain extent, and the cycle performance of the lithium battery is deteriorated faster by adopting an unsuitable charging mode for a long time. By controlling various factors influencing C1, the invention can determine an optimal C1 value for each different lithium battery, can provide a personalized charging mode for each lithium battery, is beneficial to long-term exertion of the capacity of the lithium battery and is beneficial to the cycle performance of the lithium battery.
In the above relation of the charging magnifications C1 and C2 in the first and second charging phases, the value of C2 is generally related to the fast charging requirement time, and the C2 is related to the fast charging requirement time for the maximum charging magnifications required by the fast charging requirement time, so that on one hand, it is beneficial to setting different maximum charging magnifications according to the requirements of customers, and on the other hand, it is beneficial to improving the charging efficiency of the lithium battery while ensuring the stability of the silicon/graphite anode material. While C1 is related to C2, but also to the charge ratio n2, the reversible capacity P1, the silicon content W1, the reversible capacity P2 of graphite and the graphite content W2 at the maximum current density that can be tolerated by the pre-lithium-intercalated silicon, C1 is more influenced by the reversible capacity of silicon because it determines the kinetics of lithium ion deintercalation of the silicon particles, whereas in the silicon/graphite composite anode, the silicon particles have poor ion transport capacity relative to the graphite particles and are susceptible to volume expansion causing silicon particle breakage leading to increased polarization. Therefore, in the silicon/graphite composite negative electrode, C1 and C2 meet the relation, so that the silicon particles have proper lithium intercalation speed in the initial charging process, the silicon particles have smaller internal pressure under smaller charging multiplying power C1, the silicon particles are not easy to break, the stability of the silicon particles is facilitated, the long-term capacity performance of the silicon particles is further facilitated, and the cycle performance of the lithium battery is improved. And other factors n1, W1, P2 and W2 can influence the lithium intercalation and deintercalation performance of the whole silicon/graphite composite negative electrode to a certain extent, and the cycle performance of the lithium battery is larger. Therefore, the C1 is related to the influence factors, so that the lithium intercalation-deintercalation performance and the stability of the whole silicon/graphite composite negative electrode are fully considered, and the small charging rate C1 more suitable for the lithium battery of the silicon/graphite composite negative electrode in the first charging stage is more beneficial to be obtained.
In addition, regarding the charge magnification n2 at the maximum current density that silicon can withstand, it is related to the silicon content W1, and the higher the silicon content, the smaller n 2. This is because the higher the silicon content, the lower the initial efficiency of the lithium battery, i.e., the lower the maximum current density that can be tolerated per unit mass of silicon. Therefore, the silicon content determines the charge rate at the maximum current density that silicon can withstand, and the silicon content also has a significant impact on the charging performance of the overall lithium battery system.
And switches to the second charging phase as to when the first charging phase ends, which is determined by the SOC value of the battery. When the SOC reaches the threshold b in the first charging stage, it means that a certain content of silicon in the silicon/graphite composite electrode has been intercalated with lithium, the polarization of the lithium battery is relatively low, and the remaining content of silicon and graphite can be intercalated with lithium at the same time, so that graphite particles disperse a part of internal stress, and even under a larger charging rate, the silicon particles are not broken, so that the lithium battery has better stability. The threshold b is related to the silicon ratio n1 of the pre-intercalated lithium, the silicon reversible capacity P1, the silicon content W1, the graphite reversible capacity P2 and the graphite content W2, and the lithium deintercalation performance and the stability of the silicon/graphite composite negative electrode are considered to have a larger correlation with the factors, so that the factors are comprehensively considered, the stress bearing of the silicon/graphite composite negative electrode is favorably judged, the more proper threshold b is obtained, the stability of silicon particles is ensured, and the charging efficiency of the lithium battery is improved to the greatest extent.
Preferably, w1=0.01 to 0.5, w2=1 to w1, n2=1.1 to 3.55.
Preferably, p1=1500-2000 mAh/g and p2=330-370 mAh/g.
Preferably, n1=0.4 to 0.6.
Preferably, n2=2.5 to 3.55.
When n1 or n2 are respectively in the numerical ranges, the regulation and control of the value of C1 is more favorable for the first charging stage, so that the silicon particles are not broken due to excessive internal stress when being prelithiated, the silicon particles can be prelithiated faster, the charging time of the first stage is shortened, and the charging efficiency of the whole charging process is further improved.
Preferably, in the first charging phase, the SOC of the initial charge of the lithium battery is <20%. In the first charging stage, the SOC of initial charging of the lithium battery is guaranteed to meet the conditions, lithium ions can be fully embedded in silicon particles in the process of the first charging stage, full proportion of the silicon particles are guaranteed to be prelithiated, lithium ions can be simultaneously embedded by residual silicon particles and graphite particles when the lithium ions enter the second charging stage, partial internal stress can be effectively shared by the graphite particles under the condition of high charging multiplying power, the silicon particles are prevented from being broken easily, and the stability of the silicon particles is improved.
Preferably, before the first charging phase, a precharge phase is also included; when the precharge phase ends, the SOC of the lithium battery is <10%.
Preferably, in the first charging stage, the peak value of the current density of the silicon-containing anode surface is not more than 9.2mA cm -2 . The current density on the surface of the silicon-containing anode here means the current that the anode can withstand per unit area density. The current density on the surface of the silicon-containing negative electrode is guaranteed to meet the conditions, particles in the silicon-containing negative electrode are not easy to break, stability of the silicon-containing negative electrode in a charging process is guaranteed, and the cycling stability of the lithium battery is improved.
Preferably, in the second charging stage, the peak value of the current density of the silicon-containing anode surface is not less than bmA cm -2 B=4.6×c1. The peak value of the current density on the surface of the silicon-containing anode in the second charging stage is not satisfiedBut can ensure the lithium battery to charge rapidly, improve the charging efficiency, and is favorable for the stability of the silicon-containing cathode in the whole charging process and the capacity exertion and the cycle performance of the lithium battery.
Preferably c1=0.2 to 2C. And C1 is in the numerical range, so that the stability of silicon particles in the silicon-based negative electrode in the first charging process is guaranteed, and the long-term capacity performance of silicon is exerted.
Preferably, in the silicon-containing anode, w1=0.1 to 0.3. The silicon content in the silicon-containing negative electrode is ensured to be within the range, so that on one hand, the situation that the capacity of the lithium battery cannot be effectively improved due to too little silicon content is avoided, and on the other hand, the situation that the overall expansion rate of the silicon/graphite composite negative electrode is increased due to too much silicon content can be avoided, and the cycle performance of the lithium battery is deteriorated.
Preferably, in the second charging stage, the charging rates are sequentially reduced in accordance with the highest rate C2.
Preferably, the second charging phase ends and the SOC of the lithium battery is not lower than 80%.
Preferably, in the charging method of a lithium battery with a silicon-containing anode, the method further comprises a third charging stage; in the third charging stage, the initial SOC of the lithium battery is not less than 80%.
Preferably, the lithium battery further comprises a positive electrode including a positive electrode active material including a nickel cobalt manganese ternary material.
According to another aspect of the present invention, a charging device for a lithium battery is provided, and a charging method for the lithium battery using the above-described silicon-containing anode is provided.
In order that those skilled in the art will better understand the present invention, a technical solution of the embodiments of the present invention will be clearly and completely described below, and it is apparent that the described embodiments are only some embodiments of the present invention, not all embodiments.
The following examples and comparative examples are mainly made by selecting different lithium batteries for charging, and by controlling the parameters affecting charging in each example and comparative example, the influence of the charging method provided by the invention on the charging time and cycle performance of the lithium batteries is explored.
Example 1
1. Relevant parameters of lithium battery
Through relevant tests and calculations, relevant parameters of the lithium battery in this embodiment are as follows: the reversible content P1 of silicon is 1600 mAh.g -1 The reversible content P2 of graphite is 350 mAh.g -1 The silicon content W1 is 0.1, the graphite content W2 is 0.9, the threshold a is 0.236, the silicon ratio n1 of the pre-intercalated lithium is 0.7, the charging rate n2 at the maximum current density that the silicon can withstand is 2.7, the C1 of the first charging stage is 1.9C, and the C2 of the second charging stage is set to 3C.
2. Charging of lithium batteries
The lithium battery is charged according to the following steps:
(1) A precharge phase: charging the lithium battery to 5% soc at 0.33C;
(2) A first charging stage: the lithium battery was then charged to 23.6% soc at 1.9C;
(3) A second charging stage: then taking 3C as the highest charging multiplying power, and charging the lithium battery to 80% of SOC in a reduced form of reducing 0.2C each time, wherein the final cut-off charging multiplying power in the second charging stage is 1.4C;
(4) Third charging phase: finally, the lithium battery was charged to 100% soc at 0.33C.
In the second charging stage, the specific charging operation of the lithium battery is as follows: (1) charging from 23.6% soc to 40% soc at 3C; (2) charging from 40% soc to 42% soc at 2.8C; (3) charging from 42% soc to 45% soc at 2.6C; (4) charging from 45% soc to 50% soc at 2.4C; (5) charging from 50% soc to 60% soc at 2.2C; (6) charging from 60% soc to 65% soc at 2.0C; (7) charged from 65% soc to 68% soc at 1.8C; (8) charging from 68% soc to 70% soc at 1.6C; (9) charged from 70% soc to 80% soc at 1.4C.
In addition, the time required for the first charge is taken as the charging time, and the charging time is recorded.
3. Cycle test process for lithium battery
The cycle performance test was performed on lithium batteries according to the following steps:
step 1: standing the lithium battery for 2 hours at 25 ℃ to ensure that the lithium battery reaches thermal balance;
step 2: discharging the lithium battery to 2.8V at 1/3C;
step 3: standing the lithium battery for 30min;
step 4: charging the lithium battery in the above-described charging method (reference 2. Charging of the lithium battery);
step 5: standing the lithium battery for 10min;
step 6: repeating the steps 2-5 until the battery is in a healthy state to 80% SOH.
Example 2
1. Relevant parameters of lithium battery
Through relevant tests and calculations, relevant parameters of the lithium battery in this embodiment are as follows: the reversible content P1 of silicon is 1600 mAh.g -1 The reversible content P2 of graphite is 350 mAh.g -1 The silicon content W1 is 0.1, the graphite content W2 is 0.9, the threshold a is 0.202, the silicon ratio n1 of the pre-intercalated lithium is 0.6, the charging rate n2 at the maximum current density that the silicon can withstand is 2.7, the C1 of the first charging stage is 1.6C, and the C2 of the second charging stage is set to 3C.
2. Charging of lithium batteries
The lithium battery is charged according to the following steps:
(1) A precharge phase: charging the lithium battery to 5% soc at 0.33C;
(2) A first charging stage: the lithium battery was then charged to 20.2% soc at 1.6C;
(3) A second charging stage: then taking 3C as the highest charging multiplying power, and charging the lithium battery to 80% of SOC in a reduced form of reducing 0.2C each time, wherein the final cut-off charging multiplying power in the second charging stage is 1.4C;
(4) Third charging phase: finally, the lithium battery was charged to 100% soc at 0.33C.
Wherein, in the second charging stage, the specific charging operation of the lithium battery was performed from 20.2% soc to 40% soc at 3C in (1), and the rest of the downshifting conditions were identical to those of example 1.
In addition, the time required for the first charge is taken as the charging time, and the charging time is recorded.
3. Cycle test process for lithium battery
The cycle performance test for the lithium battery in this example was identical to that of example 1.
Example 3
1. Relevant parameters of lithium battery
Through relevant tests and calculations, relevant parameters of the lithium battery in this embodiment are as follows: the reversible content P1 of silicon is 600 mAh.g -1 The reversible content P2 of graphite is 350 mAh.g -1 The silicon content W1 is 0.1, the graphite content W2 is 0.9, the threshold a is 0.135, the silicon ratio n1 of the pre-intercalated lithium is 0.4, the charging rate n2 at the maximum current density that the silicon can withstand is 2.7, the C1 of the first charging stage is 1.1C, and the C2 of the second charging stage is set to 3C.
2. Charging of lithium batteries
The lithium battery is charged according to the following steps:
(1) A precharge phase: charging the lithium battery to 5% soc at 0.33C;
(2) A first charging stage: the lithium battery was then charged to 13.5% soc at 1.1C;
(3) A second charging stage: then taking 3C as the highest charging multiplying power, and charging the lithium battery to 80% of SOC in a reduced form of reducing 0.2C each time, wherein the final cut-off charging multiplying power in the second charging stage is 1.4C;
(4) Third charging phase: finally, the lithium battery was charged to 100% soc at 0.33C.
Wherein, in the second charging stage, the specific charging operation of the lithium battery was performed from 13.5% soc to 40% soc at 3C in (1), and the remaining downshifting situation was identical to example 1.
In addition, the time required for the first charge is taken as the charging time, and the charging time is recorded.
3. Cycle test process for lithium battery
The cycle performance test for the lithium battery in this example was identical to that of example 1.
Example 4
1. Relevant parameters of lithium battery
Through relevant tests and calculations, relevant parameters of the lithium battery in this embodiment are as follows:the reversible content P1 of silicon is 1600 mAh.g -1 The reversible content P2 of graphite is 350 mAh.g -1 The silicon content W1 is 0.1, the graphite content W2 is 0.9, the threshold a is 0.101, the silicon ratio n1 of the pre-intercalated lithium is 0.3, the charging rate n2 at the maximum current density that the silicon can withstand is 2.7, the C1 in the first charging stage is 0.8C, and the C2 in the second charging stage is set to 3C.
2. Charging of lithium batteries
The lithium battery is charged according to the following steps:
(1) A precharge phase: charging the lithium battery to 5% soc at 0.33C;
(2) A first charging stage: the lithium battery was then charged to 10.1% soc at 0.8C;
(3) A second charging stage: then taking 3C as the highest charging multiplying power, and charging the lithium battery to 80% of SOC in a reduced form of reducing 0.2C each time, wherein the final cut-off charging multiplying power in the second charging stage is 1.4C;
(4) Third charging phase: finally, the lithium battery was charged to 100% soc at 0.33C.
Wherein, in the second charging stage, in the specific charging operation of the lithium battery, the 3C was charged from 10.1% soc to 40% soc in (1), and the rest of the downshifting conditions were identical to those of example 1.
In addition, the time required for the first charge is taken as the charging time, and the charging time is recorded.
3. Cycle test process for lithium battery
The cycle performance test for the lithium battery in this example was identical to that of example 1.
Example 5
1. Relevant parameters of lithium battery
Through relevant tests and calculations, relevant parameters of the lithium battery in this embodiment are as follows: the reversible content P1 of silicon is 600 mAh.g -1 The reversible content P2 of graphite is 350 mAh.g -1 The silicon content W1 is 0.1, the graphite content W2 is 0.9, the threshold a is 0.168, the silicon pre-lithium-intercalation silicon ratio n1 is 0.5, the charging rate n2 at the maximum current density that the silicon can withstand is 3.55, the C1 in the first charging stage is 1.8C, and the C2 in the second charging stage is set to 3C.
2. Charging of lithium batteries
The lithium battery is charged according to the following steps:
(1) A precharge phase: charging the lithium battery to 5% soc at 0.33C;
(2) A first charging stage: the lithium battery was then charged to 16.8% soc at 1.8C;
(3) A second charging stage: then taking 3C as the highest charging multiplying power, and charging the lithium battery to 80% of SOC in a reduced form of reducing 0.2C each time, wherein the final cut-off charging multiplying power in the second charging stage is 1.4C;
(4) Third charging phase: finally, the lithium battery was charged to 100% soc at 0.33C.
Wherein, in the second charging stage, the specific charging operation of the lithium battery was performed from 16.8% soc to 40% soc at 3C in (1), and the remaining downshifting situation was identical to example 1.
In addition, the time required for the first charge is taken as the charging time, and the charging time is recorded.
3. Cycle test process for lithium battery
The cycle performance test for the lithium battery in this example was identical to that of example 1.
Example 6
1. Relevant parameters of lithium battery
Through relevant tests and calculations, relevant parameters of the lithium battery in this embodiment are as follows: the reversible content P1 of silicon is 1600 mAh.g -1 The reversible content P2 of graphite is 350 mAh.g -1 The silicon content W1 is 0.1, the graphite content W2 is 0.9, the threshold a is 0.168, the silicon pre-lithium-intercalation silicon ratio n1 is 0.5, the charging rate n2 at the maximum current density that the silicon can withstand is 3.5, the C1 in the first charging stage is 1.78C, and the C2 in the second charging stage is set to 3C.
2. Charging of lithium batteries
The lithium battery is charged according to the following steps:
(1) A precharge phase: charging the lithium battery to 5% soc at 0.33C;
(2) A first charging stage: the lithium battery was then charged to 16.8% soc at 1.78C;
(3) A second charging stage: then taking 3C as the highest charging multiplying power, and charging the lithium battery to 80% of SOC in a reduced form of reducing 0.2C each time, wherein the final cut-off charging multiplying power in the second charging stage is 1.4C;
(4) Third charging phase: finally, the lithium battery was charged to 100% soc at 0.33C.
Wherein, in the second charging stage, the specific charging operation of the lithium battery was performed from 16.8% soc to 40% soc at 3C in (1), and the remaining downshifting situation was identical to example 1.
In addition, the time required for the first charge is taken as the charging time, and the charging time is recorded.
3. Cycle test process for lithium battery
The cycle performance test for the lithium battery in this example was identical to that of example 1.
Example 7
1. Relevant parameters of lithium battery
Through relevant tests and calculations, relevant parameters of the lithium battery in this embodiment are as follows: the reversible content P1 of silicon is 1600 mAh.g -1 The reversible content P2 of graphite is 350 mAh.g -1 The silicon content W1 is 0.1, the graphite content W2 is 0.9, the threshold a is 0.168, the silicon pre-lithium-intercalation silicon ratio n1 is 0.5, the charging rate n2 at the maximum current density that the silicon can withstand is 2.5, the C1 in the first charging stage is 1.3C, and the C2 in the second charging stage is set to 3C.
2. Charging of lithium batteries
The lithium battery is charged according to the following steps:
(1) A precharge phase: charging the lithium battery to 5% soc at 0.33C;
(2) A first charging stage: the lithium battery was then charged to 16.8% soc at 1.3C;
(3) A second charging stage: then taking 3C as the highest charging multiplying power, and charging the lithium battery to 80% of SOC in a reduced form of reducing 0.2C each time, wherein the final cut-off charging multiplying power in the second charging stage is 1.4C;
(4) Third charging phase: finally, the lithium battery was charged to 100% soc at 0.33C.
Wherein, in the second charging stage, the specific charging operation of the lithium battery was performed from 16.8% soc to 40% soc at 3C in (1), and the remaining downshifting situation was identical to example 1.
In addition, the time required for the first charge is taken as the charging time, and the charging time is recorded.
3. Cycle test process for lithium battery
The cycle performance test for the lithium battery in this example was identical to that of example 1.
Example 8
1. Relevant parameters of lithium battery
Through relevant tests and calculations, relevant parameters of the lithium battery in this embodiment are as follows: the reversible content P1 of silicon is 1600 mAh.g -1 The reversible content P2 of graphite is 350 mAh.g -1 The silicon content W1 is 0.1, the graphite content W2 is 0.9, the threshold a is 0.168, the silicon ratio n1 of the pre-intercalated lithium is 0.5, the charging rate n2 at the maximum current density that the silicon can withstand is 1.1, the C1 in the first charging stage is 0.6C, and the C2 in the second charging stage is set to 3C.
2. Charging of lithium batteries
The lithium battery is charged according to the following steps:
(1) A precharge phase: charging the lithium battery to 5% soc at 0.33C;
(2) A first charging stage: the lithium battery was then charged to 16.8% soc at 0.6C;
(3) A second charging stage: then taking 3C as the highest charging multiplying power, and charging the lithium battery to 80% of SOC in a reduced form of reducing 0.2C each time, wherein the final cut-off charging multiplying power in the second charging stage is 1.4C;
(4) Third charging phase: finally, the lithium battery was charged to 100% soc at 0.33C.
In the second charging phase, the case of reduction in the specific charging operation of the lithium battery was identical to example 1.
In addition, the time required for the first charge is taken as the charging time, and the charging time is recorded.
3. Cycle test process for lithium battery
The cycle performance test for the lithium battery in this example was identical to that of example 1.
Example 9
1. Relevant parameters of lithium battery
Through relevant tests and calculations, relevant parameters of the lithium battery in this embodiment are as follows: the reversible content P1 of silicon is 1600 mAh.g -1 The reversible content P2 of graphite is 350 mAh.g -1 The silicon content W1 is 0.15, the graphite content W2 is 0.85, the threshold a is 0.237, the silicon ratio n1 of the pre-intercalated lithium is 0.7, the charging rate n2 at the maximum current density that the silicon can withstand is 2.7, the C1 of the first charging stage is 1.9C, and the C2 of the second charging stage is set to 3C.
2. Charging of lithium batteries
The lithium battery is charged according to the following steps:
(1) A precharge phase: charging the lithium battery to 5% soc at 0.33C;
(2) A first charging stage: the lithium battery was then charged to 23.7% soc at 1.9C;
(3) A second charging stage: then taking 3C as the highest charging multiplying power, and charging the lithium battery to 80% of SOC in a reduced form of reducing 0.2C each time, wherein the final cut-off charging multiplying power in the second charging stage is 0.4C;
(4) Third charging phase: finally, the lithium battery was charged to 100% soc at 0.33C.
Wherein, in the second charging stage, the specific charging operation of the lithium battery was performed from 23.7% soc to 40% soc at 3C in (1), and the remaining downshifting situation was identical to example 1.
In addition, the time required for the first charge is taken as the charging time, and the charging time is recorded.
3. Cycle test process for lithium battery
The cycle performance test for the lithium battery in this example was identical to that of example 1.
Example 10
1. Relevant parameters of lithium battery
Through relevant tests and calculations, relevant parameters of the lithium battery in this embodiment are as follows: the reversible content P1 of silicon is 1600 mAh.g -1 The reversible content P2 of graphite is 350 mAh.g -1 The silicon content W1 is0.1, a graphite content W2 of 0.9, a threshold value a of 0.168, a silicon pre-intercalating lithium of 0.5 with a silicon ratio n1, a charging rate n2 at maximum current density that silicon can withstand of 3.7, C1 in the first charging stage of 0.4C, and C2 in the second charging stage of 3C.
2. Charging of lithium batteries
The lithium battery is charged according to the following steps:
(1) A precharge phase: charging the lithium battery to 5% soc at 0.33C;
(2) A first charging stage: the lithium battery was then charged to 16.8% soc at 1.9C;
(3) A second charging stage: then taking 3C as the highest charging multiplying power, and charging the lithium battery to 80% of SOC in a reduced form of reducing 0.2C each time, wherein the final cut-off charging multiplying power in the second charging stage is 0.4C;
(4) Third charging phase: finally, the lithium battery was charged to 100% soc at 0.33C.
Wherein, in the second charging stage, the specific charging operation of the lithium battery was performed from 16.8% soc to 40% soc at 3C in (1), and the remaining downshifting situation was identical to example 1.
In addition, the time required for the first charge is taken as the charging time, and the charging time is recorded.
3. Cycle test process for lithium battery
The cycle performance test for the lithium battery in this example was identical to that of example 1.
Example 11
1. Relevant parameters of lithium battery
Through relevant tests and calculations, relevant parameters of the lithium battery in this embodiment are as follows: the reversible content P1 of silicon is 1600 mAh.g -1 The reversible content P2 of graphite is 350 mAh.g -1 The silicon content W1 is 0.1, the graphite content W2 is 0.9, the threshold a is 0.168, the silicon ratio n1 of the pre-intercalated lithium is 0.5, the charging rate n2 at the maximum current density that the silicon can withstand is 0.8, the C1 in the first charging stage is 1.9C, and the C2 in the second charging stage is set to 3C.
2. Charging of lithium batteries
The lithium battery is charged according to the following steps:
(1) A precharge phase: charging the lithium battery to 5% soc at 0.33C;
(2) A first charging stage: the lithium battery was then charged to 16.8% soc at 0.4C;
(3) A second charging stage: then taking 3C as the highest charging multiplying power, and charging the lithium battery to 80% of SOC in a reduced form of reducing 0.2C each time, wherein the final cut-off charging multiplying power in the second charging stage is 1.4C;
(4) Third charging phase: finally, the lithium battery was charged to 100% soc at 0.33C.
Wherein, in the second charging stage, the specific charging operation of the lithium battery was performed from 16.8% soc to 40% soc at 3C in (1), and the remaining downshifting situation was identical to example 1.
In addition, the time required for the first charge is taken as the charging time, and the charging time is recorded.
3. Cycle test process for lithium battery
The cycle performance test for the lithium battery in this example was identical to that of example 1.
Example 12
1. Relevant parameters of lithium battery
The relevant parameters of the lithium battery in this example were identical to those of example 1 except that C2 was not identical to example 1, wherein C2 was set to 2C.
2. Charging of lithium batteries
The lithium battery is charged according to the following steps:
(1) A precharge phase: charging the lithium battery to 5% soc at 0.33C;
(2) A first charging stage: the lithium battery was then charged to 23.6% soc at 1.9C;
(3) A second charging stage: then taking 2C as the highest charging multiplying power, and charging the lithium battery to 80% of SOC in a reduced form of reducing 0.2C each time, wherein the final cut-off charging multiplying power in the second charging stage is 0.4C;
(4) Third charging phase: finally, the lithium battery was charged to 100% soc at 0.33C.
In the second charging stage, the specific charging operation of the lithium battery is as follows: (1) charged from 23.6% soc to 65% soc at 2C; (2) charged from 65% soc to 68% soc at 1.8C; (3) charging from 68% soc to 70% soc at 1.6C; (4) charging from 70% soc to 80% soc at 1.4C; (5) charged from 80% soc to 100% soc at 0.33C.
In addition, the time required for the first charge is taken as the charging time, and the charging time is recorded.
3. Cycle test process for lithium battery
The cycle performance test for the lithium battery in this example was identical to that of example 1.
Comparative example 1
1. Relevant parameters of lithium battery
The present comparative example charges the lithium battery directly with the large magnification C2, and thus there is no first charging stage of the small magnification C1, i.e., the lithium battery goes directly to the second charging stage after undergoing the precharge stage, and C2 of the second charging stage is set to 3C. And the relevant parameters of the lithium battery in this comparative example are as follows: the reversible content P1 of silicon is 1600 mAh.g -1 The reversible content P2 of graphite is 350 mAh.g -1 The silicon content W1 was 0.1, and the graphite content W2 was 0.9.
2. Charging of lithium batteries
The lithium battery is charged according to the following steps:
(1) A precharge phase: charging the lithium battery to 5% soc at 0.33C;
(2) A second charging stage: then taking 3C as the highest charging multiplying power, and charging the lithium battery to 80% of SOC in a reduced form of reducing 0.2C each time, wherein the final cut-off charging multiplying power in the second charging stage is 0.4C;
(3) Third charging phase: finally, the lithium battery was charged to 100% soc at 0.33C.
In the second charging stage, the specific charging operation of the lithium battery is as follows: (1) charging from 5% soc to 40% soc at 3C; (2) charging from 40% soc to 42% soc at 2.8C; (3) charging from 42% soc to 45% soc at 2.6C; (4) charging from 45% soc to 50% soc at 2.4C; (5) charging from 50% soc to 60% soc at 2.2C; (6) charging from 60% soc to 65% soc at 2.0C; (7) charged from 65% soc to 68% soc at 1.8C; (8) charging from 68% soc to 70% soc at 1.6C; (9) charged from 70% soc to 80% soc at 1.4C.
In addition, the time required for the first charge is taken as the charging time, and the charging time is recorded.
3. Cycle test process for lithium battery
The cycle performance test for the lithium battery in this comparative example was identical to that of example 1.
Comparative example 2
1. Relevant parameters of lithium battery
Through relevant tests and calculation, relevant parameters of the lithium battery in the comparative example are as follows: the reversible content P1 of silicon is 1600 mAh.g -1 The reversible content P2 of graphite is 350 mAh.g -1 The silicon content W1 is 0.1, the graphite content W2 is 0.9, the threshold a is 0.303, the silicon ratio n1 of the pre-intercalated lithium is 0.9, the charging rate n2 at the maximum current density that the silicon can withstand is 3, C1 in the first charging stage is 2.7C, and C2 in the second charging stage is set to 3C.
2. Charging of lithium batteries
The lithium battery is charged according to the following steps:
(1) A precharge phase: charging the lithium battery to 5% soc at 0.33C;
(2) A first charging stage: the lithium battery was then charged to 30.3% soc at 2.7C;
(3) A second charging stage: then taking 3C as the highest charging multiplying power, and charging the lithium battery to 80% SOC in a reduced form of reducing 0.2C each time, wherein the final cut-off charging multiplying power in the second charging stage is 0.4C; (4) a third charging phase: finally, the lithium battery was charged to 100% soc at 0.33C.
Wherein, in the second charging stage, in the specific charging operation of the lithium battery, the 3C was charged from 30.3% soc to 40% soc in (1), and the rest of the downshifting conditions were identical to those of example 1.
In addition, the time required for the first charge is taken as the charging time, and the charging time is recorded.
3. Cycle test process for lithium battery
The cycle performance test for the lithium battery in this comparative example was identical to that of example 1.
Comparative example 3
1. Relevant parameters of lithium battery
Through relevant tests and calculation, relevant parameters of the lithium battery in the comparative example are as follows: the reversible content P1 of silicon is 1600 mAh.g -1 The reversible content P2 of graphite is 350 mAh.g -1 The silicon content W1 is 0.1, the graphite content W2 is 0.9, the threshold value a is 0.067, the silicon ratio n1 of the pre-intercalated lithium is 0.2, the charging rate n2 at the maximum current density that the silicon can withstand is 3, C1 in the first charging stage is 0.6C, and C2 in the second charging stage is set to 3C.
2. Charging of lithium batteries
The lithium battery is charged according to the following steps:
(1) A precharge phase: charging the lithium battery to 5% soc at 0.33C;
(2) A first charging stage: the lithium battery was then charged to 6.7% soc at 0.6C;
(3) A second charging stage: then taking 3C as the highest charging multiplying power, and charging the lithium battery to 80% SOC in a reduced form of reducing 0.2C each time, wherein the final cut-off charging multiplying power in the second charging stage is 0.4C; (4) a third charging phase: finally, the lithium battery was charged to 100% soc at 0.33C.
Wherein, in the second charging stage, the specific charging operation of the lithium battery was performed, the 3C was charged from 6.7% soc to 40% soc in (1), and the rest of the downshifting conditions were identical to those of example 1.
In addition, the time required for the first charge is taken as the charging time, and the charging time is recorded.
3. Cycle test process for lithium battery
The cycle performance test for the lithium battery in this comparative example was identical to that of example 1.
Test results
Table 1 below is the results of the cycle performance test and the related parameters concerning the batteries in the above examples and comparative examples.
Table 1 results of testing relevant parameters and cycle performance of the batteries in examples and comparative examples
As can be seen from table 1, the charging method of the present invention can be used to charge a lithium battery, so that the lithium battery can be rapidly charged, and the lithium battery can have good cycle performance, and the data in table 1 can be referred to. The charging method is characterized in that the lithium battery is charged by adopting the smaller charging multiplying power C1, and then the lithium battery is charged by adopting the larger charging multiplying power C2, so that the stability of silicon particles in the silicon-containing negative electrode in the charging process is improved, the silicon particles are not easy to break, the long-term capacity performance of the silicon particles is improved, the capacity attenuation rate of the lithium battery in a quick charging cycle is reduced, and the cycle performance of the lithium battery is improved while the charging time is shortened. In addition, the charging method can determine an optimal C1 value for each different lithium battery by controlling various factors influencing C1, can provide a personalized charging mode for each lithium battery, is beneficial to long-term exertion of the capacity of the lithium battery and is beneficial to the cycle performance of the lithium battery.
As can be seen from examples 1 to 6, the value of n1 has an effect on the balance of the charging time and the cycle performance of the lithium battery, and when n1 is between 0.4 and 0.6, the balance of the charging time and the cycle performance of the lithium battery is more facilitated, and the cycle performance of the battery can be further optimized while realizing a shorter charging time.
It can be seen from examples 5, 6, 7 and 8 that the value of n2 has a certain influence on the balance of the charging time and the cycle performance of the lithium battery, and when n2 is between 2.5 and 3.55, the balance of the charging time and the cycle performance of the lithium battery is more favorable. In comparative example 1, the lithium battery was directly charged with the high rate C2, and the silicon particles were subjected to excessive stress at one time, so that the silicon particles were easily broken and the stability was lowered, thereby deteriorating the cycle performance of the lithium battery. Since the value of n1 in comparative examples 2 and 3 is not in the range of 0.3 to 0.7, the cycle performance or the charging time of the lithium battery is deteriorated to some extent, which means that keeping n1 in a proper range is significant for the balance between the charging time and the cycle performance of the lithium battery.
The above embodiments are only for illustrating the technical solution of the present invention and not for limiting the scope of the present invention, and although the present invention has been described in detail with reference to the above embodiments, it should be understood by those skilled in the art that modifications or equivalent substitutions can be made to the technical solution of the present invention, but these modifications or substitutions are all within the scope of the present invention.
Claims (12)
1. A charging method of a lithium battery with a silicon-containing negative electrode is characterized by comprising the following steps: comprises a first charging stage and a second charging stage;
in the first charging stage, charging with a C1 rate; in the second charging stage, charging with a C2 rate;
wherein, C1 and C2 satisfy the following relation: c1 =n1×n2×c2× (p1×w1)/(p1×w1+p2×w2);
wherein n1=0.3 to 0.7, n2=3.6 to 5×w1; c2 =1.25 to 12;
wherein, in the silicon-containing anode, the anode active material includes silicon and graphite, P1 represents a silicon reversible capacity, P2 represents a graphite reversible capacity, W1 represents a silicon content, and W2 represents a graphite content;
in the charging process of the lithium battery, when the SOC value of the lithium battery reaches a threshold value a in the first charging stage, the first charging stage is ended and is switched to the second charging stage;
where a=n1× (p1×w1)/(p1×w1+p2×w2).
2. The method for charging a lithium battery having a silicon-containing anode according to claim 1, wherein: w1=0.01 to 0.5, w2=1 to w1, n2=1.1 to 3.55.
3. The method for charging a lithium battery having a silicon-containing anode according to claim 1, wherein: p1=1500-2000 mAh/g, p2=330-370 mAh/g.
4. The method for charging a lithium battery having a silicon-containing anode according to claim 1, wherein: n1=0.4 to 0.6.
5. The method for charging a lithium battery having a silicon-containing anode as claimed in claim 2, wherein: n2=2.5 to 3.55.
6. The method for charging a lithium battery having a silicon-containing anode according to claim 1, wherein: in the first charging phase, the lithium battery has an SOC of <20% of initial charge.
7. The method for charging a lithium battery having a silicon-containing anode as claimed in claim 6, wherein: before the first charging phase, a precharge phase is further included;
when the precharge phase ends, the SOC of the lithium battery is <10%.
8. The method for charging a lithium battery having a silicon-containing anode according to claim 1, wherein: in the first charging stage, the peak value of the current density of the silicon-containing anode surface is not more than 9.2mA cm -2 。
9. The method for charging a lithium battery having a silicon-containing anode according to claim 8, wherein: in the second charging stage, the peak value of the current density of the silicon-containing anode surface is not less than bmA cm -2 ，b＝4.6×C1。
10. The method for charging a lithium battery having a silicon-containing anode according to claim 1, wherein: c1 =0.6 to 2C.
11. The method for charging a lithium battery having a silicon-containing anode as claimed in claim 2, wherein: in the silicon-containing anode, w1=0.1 to 0.3.
12. A charging device for a lithium battery, characterized in that: a charging method of a lithium battery employing the silicon-containing anode as claimed in any one of claims 1 to 11.
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